Personal Electronics For Law Enforcement Solid State Recorders And Body Wires Olympus Microcassette Recorder DW 90 210488

User Manual: Olympus Microcassette Recorder DW-90

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The author(s) shown below used Federal funds provided by the U.S.

Department of Justice and prepared the following final report:

Document Title: Personal Electronics for Law Enforcement Solid

State Recorders and Body Wires

Author(s): William Butler ; Scott Crowgey ;

William Heineman ; Susan Gourley

Document No.: 210488

Date Received: July 2005

Award Number: 2001-RD-R-061

This report has not been published by the U.S. Department of Justice.

To provide better customer service, NCJRS has made this Federally-

funded grant final report available electronically in addition to

traditional paper copies.

Opinions or points of view expressed are those

of the author(s) and do not necessarily reflect

the official position or policies of the U.S.

Department of Justice.

Personal Electronics for Law Enforcement

Solid State Recorders and Body Wires

William Butler, Georgia Tech Research Institute

Scott Crowgey, Georgia Tech Research Institute

William Heineman, Tektron

Susan Gourley, Tektron

Prepared Under:

Contract Number N65236-00-K-7805

Submitted to:

Attention: Mr. Richard Baker, Code 741

Mr. Jerry Owens, Code 741JO

Commanding Officer

SPAWARSYSCEN Charleston

PO Box 190022

North Charleston, SC 29419-9022

July 2002

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

CONTENTS

• Introduction

• Current Commercial Solid State Recorder Products

• Overview of Commercial Audio Recorder Products

• Commercial Audio Recorder Issues

• Current and Projected State of the Art in Solid State Recorder Technology Areas

• Block Diagram of a Typical Solid State Recorder

• Microphones

• Delta Sigma Analog to Digital Converters

• Audio Compression Algorithms

• Audio Compression Hardware

• Flash Memory

• Batteries

• Projected Commercial Solid State Recorder Products (in 2 years)

• Solid State Recorder Conclusions

• Current Body Wire Products

• Overview of Body Wire Products

• Body Wire Issues

• Current and Projected State of the Art in Body Wire Technology Areas

• Block Diagram of a Typical Body Wire

• Projected Commercial Body Wire Products (in 2 years)

• Body Wire Conclusions

• APPENDIX A – Solid State Recorder Product Matrix

• APPENDIX B – Solid State Recorder Components

• APPENDIX C – Body Wire Product Source Matrix

• APPENDIX D – Survey of Recorder and Body Wire Use by Law Enforcement Agencies

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

1. INTRODUCTION

This report summarizes the work performed by the Communications Networking Division

(CND) of the Information and Telecommunications Technology Laboratory (ITTL) of Georgia

Tech Research Institute (GTRI) under the "Personal Electronics for Law Enforcement" program.

This program is being performed for the SPAWARSYSCEN Charleston. The report covers

work done as part of a joint effort between GTRI, and Tektron, Inc. GTRI’s efforts are focused

on solid state audio recorders that could be used for law enforcement applications, and Tektron’s

efforts are focused on body wires for law enforcement applications.

This report includes information that is intended to assist the law enforcement community in the

evaluation and purchase of audio recorders and body wires. It includes a market survey of

commercially available audio recorder and body wire products, and it includes a brief review of

key technologies used in these products. The first section of the report covers audio recorders,

and the second section covers body wires. In addition, an appendix contains the results of a

survey of law enforcement agencies that deals with the use of recorders and body wires for law

enforcement applications.

2. COMMERCIAL SOLID STATE AUDIO RECORDER PRODUCTS

Throughout this program, data has been collected on commercial-off-the-shelf (COTS) audio

recorders that could be used for law enforcement applications. An incredible variety of recorders

are available, including solid state audio recorders based on flash memory. Since solid state

recorders have no moving parts, they can offer higher fidelity recordings than conventional

cassette recorders. The solid state recorder does not suffer from background tape hiss or tape

speed variations that degrade the fidelity of cassette recorders. For these reasons, special

emphasis has been placed on solid state recorders in this study. For comparison with solid state

recorders, data has also been collected on MP3 recorder/players, mini disc recorder/players, and

digital audio tape recorder/players.

2.1 Overview of Commercial Audio Recorder Products

Table 2-1 presents a summary of the performance of various kinds of audio recorders. A solid

state flash recorder (made by Olympus), a MP3 recorder (made by Creative Labs), a mini disc

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

recorder (made by Sony), and a microcassette recorder (made by Sony) are all compared in the

table. This table does not include all the devices reviewed in the survey, but instead, includes

devices that typify the performance of commercially available audio recorders that would be

suitable for law enforcement applications. Data in the table is current as of July 2002.

Table 2-1. Audio Recorder Feature Summary

Recorder Type Size Record Time Fidelity Cost Media Cost

Flash

(Olympus

DS2000)

4.3”x2”x0.65” 22hrsLP64MB

10hrsSP64MB

5hrsLP16MB

2hrsSP16MB

300-3kHz

300-5kHz

DSS format

$175

with

32MB

$50 64MB

$15 16MB

Smartmedia

card

MP3

(Creative Labs

Nomad IIc)

3.7”x2.6”x0.9” 133min 32MB

66min 16MB

G721

ADPCM

format

$114

with

64MB

$30 32MB

$15 16MB

Smartmedia

card

Minidisc

(Sony

MZ-N707)

3.25”x3”x1.3” 5 hrs 1 MD ATRAC3

format

$230 $2.50 minidisc

Digital Audio

Tape (Sony

TCD-D100)

1.125”x3.125”x

4.625”

120 min

90 min

60 min

20-22kHz $750 $5.50 120min

$4.50 90min

$4.00 60min

Microcassette

(Sony M850V)

4”x2.25”x0.88” 120 min

90 min

60 min

250-4000Hz $65 $2.50 120min

$1.50 90min

microcassette

From the table, it is seen that all the devices are available in similar sizes, and all devices are

capable of at least 2 hours of record time. The Olympus voice recorder and the MP3

player/recorder have similar frequency response to the microcassette. The ATRAC3

compression used by the minidisc recorder and the digital audio tape have the best bandwidth.

In the cost category, the MP3 player/recorder is the next lowest cost after the microcassette. In

the media cost category, the minidisc is the lowest after the microcassette.

2.1.1 Flash Audio Recorders

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

The flash based audio recorder is the main subject of this report. It offers a number of potential

advantages: high fidelity, high reliability, small size, and reasonable cost (cost of both the

recorder and the recording medium). Flash recorders have benefited from the proliferation of the

use of flash memory for digital cameras and MP3 players over the past few years, and the cost of

flash audio recorders has come down as a result. The material to follow describes the features of

several representative commercially available flash audio recorder products.

The Olympus flash audio recorders are available in several models. The DS2000 is listed in the

table. The DM-1 is also available for approximately the same cost, and has the added ability to

play back MP3 music recordings. The DM-1 does not provide protection against accidental

erasure. The Olympus DW-90 flash audio recorder costs approximately $90, has a non-

removable 8MB flash memory, uses ADPCM compression, and can record from 22 (5.8kHz) to

90 (1.7kHz) minutes of audio. The DS2000 and DM-1 Olympus flash recorders use a file format

called Digital Speech Standard (DSS). Files stored in this format occupy 12 times less memory

space than uncompressed WAV files, while achieving roughly the same audio quality. Olympus

flash voice recorders feature voice-activated recording that can be switched off. Olympus voice

recorders use a standard USB interface to transfer data from the recorder to a PC. The Olympus

recorders can record in monaural mode, but not stereo. Further information on these products

may be obtained at the manufacturer’s web site:

http://www.olympusamerica.com/cpg_section/cpg_vr_digitalrecorders.asp.

The Panasonic RR-XR320 is another example of a flash audio recorder. The RR-XR320 is 1

7/8” x 3 9/16” x ½” in size, uses ADPCM recording and uses SD flash memory. It has a battery

life of 11 hours when recording, and uses two AAA batteries. The MSRP of the RR-XR320 is

$329, and street prices around $280 are common. This flash recorder uses a standard USB

interface to transfer data from the recorder to a PC. It can record up to 150 minutes in “LP”

mode with a 16MB SD flash memory card. High quality (HQ), standard play (SP), and long play

(LP) recording modes are available. Further information on this product may be obtained from

the manufacturer’s web site:

http://www.prodcat.panasonic.com/shop/NewDesign/ModelTemplate.asp?ModelID=13081.

The Sony ICD-MS515 is another audio recorder that uses flash memory (in the form of a

memory stick). It is 1/3/8” x 4 1/8” x 23/32” in size, and uses 2 AAA batteries. The MSRP is

$250. It can record for 10 hours in SP mode, and 12 hours in LP mode on a single set of

batteries. It has voice activated recording, and uses a standard USB interface to transfer data

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

from the recorder to a PC. It can record 64 minutes in SP mode (using 16kHz sampling), and

150 minutes in LP mode (using 8kHz sampling). It features a built in omnidirectional

microphone, and is a monaural recorder. Sony also makes a less expensive flash recorder (ICD-

B25) without removable media for $100. Further information on these products may be obtained

from the manufacturer’s web site:

http://www.sonystyle.com/electronics/prd.jsp?hierc=8627x8667x8668&catid=8668&pid=31982

&type=p.

The DIALOG4/ORBAN SOUNTAINER MP3 player/recorder is another example of a compact

audio recorder that uses flash memory in a multimedia card (MMC) format. Instead of ADPCM

or DSS, it uses MP3 recording of audio. It is comparable in size and features to other recorders.

This manufacturer prefers that detailed information on its recorder specifications should not be

reproduced. So, for more information on this recorder, the reader is referred to the

manufacturer’s web site: http://www.dialog4.com/products/sountainer/supp_snt1.html.

Please note that solid state audio recorders from Adaptive Digital Systems (EAGLE/FBIRD8)

are available for law enforcement purposes. For specifications on these products, please see

http://www.adaptivedigitalsystems.com. A password, which may be obtained from the

manufacturer, is required to access the specifications for these recorders.

Another manufacturer of solid state audio recorders for law enforcement purposes is Digital

Audio Corporation. The product made by this corporation is the SSABR, which is described as a

“state of the art, body worn digital recorder, specifically designed for collecting accurate, covert

recordings.” Details on this product may be found at http://www.dacaudio.com. A password,

which may be obtained from the manufacturer, is required to access this data.

Yet another manufacturer of solid state audio recorders for law enforcement applications is

Geonautics. This company makes a very small “Whisper” flash based recorder that is available

in both mono and stereo configurations. Details on these products may be found at

http://www.geonautics.com. A password, which may be obtained from the manufacturer, is

required to access this data.

2.1.2 MP3 Player/Audio Recorders

Another class of commercial product with potential application for covert recording is the MP3

player. MP3, or MPEG Layer 3, is a lossy compression format that allows CD-quality music

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

recordings to be compressed into files significantly reduced in size to facilitate transfer over the

internet and to and from PC’s. MPEG formats accomplish this reduction in size partly by

eliminating components of the recording that would be masked by the human hearing process

based on a psychoacoustic model of hearing.

Many, but not all, MP3 players have voice recording capability in addition to MP3 playback

capabilities. The MP3 playback frequency response is listed as a very high quality range of

20Hz to 20kHz. Unfortunately, the claimed frequency response of 20Hz – 20kHz applies only to

the playback of MP3 files, not to recorded voice. The portable MP3 recorder/players reviewed

to date use ADPCM for recording voice. The ADPCM implementations used have a bandwidth

of 3 to 4kHz, which is much worse than the 20-20kHz achieved when playing back MP3

recordings. The ADPCM used in the voice recordings is based on 8 bit PCM samples, and has

an upper limit of approximately 50dB for its signal to noise ratio.

The Creative Labs Nomad IIc MP3 player/recorder is a widely available MP3 player/recorder

that can be used for recording audio onto flash memory (Smartmedia format flash). It is 3.7” x

2.6” x 0.9” in size, and uses 32kbps G721 (an ITU standard) ADPCM recording. It features a

USB interface for transferring files to a PC. Further information on this device may be obtained

from the manufacturer’s web site:

http://www.americas.creative.com/products/category.asp?category=2&maincategory=2.

The Sensory Science Rave MP2200 samples voice at 8kHz, and requires approximately 1MB of

flash memory space for every 4 minutes of voice recording. So, for a built in flash memory of

64MB, this unit can store over 4 hours of voice. The specification of approximately 4 minutes of

voice per 1MB indicates that some compression is being used to store the voice (approximately a

2:1 compression), which is consistent with 32kbps G721 ADPCM. Unfortunately, the Rave

MP2200 does not store voice files on removable media, but only on the built in flash. Cost of

the Rave MP2200 is approximately $200. More information on the Rave MP2200 may be

obtained at the following URL:

http://www.sonicblue.com/support/goVideo/downloads/MP2200manual.pdf.

A few of the MP3 recorder/players use 40 MB Iomega Clik! disks as the storage media, which

are much cheaper than the removable flash cards. However, these disks are susceptible to shock

and vibration, which could be a disadvantage for certain law enforcement applications.

2.1.3 Minidisc Player/Audio Recorders

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

A third interesting class of commercial products with potential for covert recording applications

is the minidisc recorder/player. The minidisc is the most compact of the removable memory

storage media, capable of storing approximately 160 MB of audio data on a disc that is 64 mm in

diameter and approximately 1 mm thick. A typical minidisc device is not much bigger than the

minidisc itself, with typical dimensions of 70 mm x 67.5 mm x 5 mm and being very similar in

size to the MP3 player/recorders discussed above. Only Sharp and Sony currently produce

minidisc recorder/players. These are the only COTS products reviewed so far that can make

voice recordings in stereo and that can record voice using the full 44.1 kHz, 16 bit sampling that

is a standard for audio CD’s, allowing the full recording bandwidth for music or voice of 20 Hz

to 20 kHz. However, to store audio with this large a bandwidth on the limited amount of

memory space available, all minidiscs utilize a proprietary ATRAC3 compression scheme for the

storage of data that is lossy, compressing the audio files by a ratio of approximately 4.83:1. Both

Sharp and Sony have plans to produce higher density minidiscs and drives with a capacity of

about 650 MB.

Pre-recorded minidiscs are fabricated using the same plastic-aluminum structure as CD’s. The

minidisc is read by focusing a laser on pits and valleys within the transparent polycarbonate

substrate backed by a coating of aluminum that then reflects or disperses the beam to produce a

series or 1’s and 0’s which can then be translated back into either the original data or sound.

Recordable minidiscs have a pre-groove instead of the CD-type pits and valleys and a MO

(magneto-optical) coating instead of the aluminum one. While recording, the laser focuses on

the pre-groove and heats the MO recording layer at that point to its Curie point while a magnetic

field from a head in contact with the other side of the disc aligns magnetic dipoles within the

heated spot on the MO layer. During playback, the laser focuses on the pre-groove again, but at

a lower power, allowing the measurement of changes in the polarization of the light reflected

from the previously magnetized layer. All minidisc players have a dual function optical

assembly that detects the disc type and switches between the measurement of reflectivity for pre-

recorded minidiscs or polarization for recordable minidiscs. Sony claims recordable minidiscs

can handle up to 1 million recordings. The minidiscs have a user table of contents that can be

damaged if the minidisc is abused and render the minidisc unusable. Sony claims that data using

magneto-optical technology can be stored for more than 30 years without loss or degradation.

However, strong magnets placed directly against the minidisc can destroy data.

Minidiscs use a buffer memory that temporarily stores recorded audio, thereby helping to prevent

vibrations from affecting either the recording onto or playback from the minidisc. However,

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

problems have been reported with recording when the minidisc recorder is subjected to shock

and vibration, apparently due to the laser beam “skipping” and accidentally erasing previously

recorded data on adjacent tracks. Therefore, it is recommended that the recorder should be

immobile and not subjected to shock or vibration while recording. In addition, because of the

400-900 rpm rotation of the minidisc, all such devices produce a humming noise when recording

or playing audio. Although this humming noise reportedly does not degrade the recording or

playback process, it could possibly interfere with the covert recording process. Because the laser

beam must heat the disk while recording, the minidisc device is the only portable recording

device that consumes more power during recording than during playback. And even during

playback, the devices still consume 50-100% more power than any other class of recording

device. Until recently, none of the minidisc recorder/players have had a convenient means to

connect to a PC to allow the rapid transfer of files.

The Sony MZ-N707 minidisc recorder offers some of the advantages of flash recorders. It

records onto a digital medium (the minidisc), and is not subject to the tape hiss that is present in

cassettes. The minidisc must spin to work, so, unlike flash recorders, there are moving parts

inside the minidisc recorder. The size of the MN-N707 is 3 ¼” x 3” x 1 1/8”. It comes with a

rechargeable battery, and records in a high fidelity ATRAC3 format. An external microphone is

needed to record audio, since the unit does not come with a built in microphone. It uses Sony’s

ATRAC3 compression technique for storing audio (and music). The ATRAC3 compression

technique achieves relatively high fidelity, but it is not lossless. Another model, the MZ-N1, is

available for $350, and it is somewhat smaller in size: 3” x 2 7/8” x ½”. The MZ-N1 features a

higher capacity battery than the MZ-N707. Further information on these devices may be found

at the following URL:

http://www.sonystyle.com/electronics/ssctypg.jsp?hierc=8627x8650x8647&catid=8647.

2.1.4 Digital Audio Tape (DAT) Recorders

One DAT device, a TCD-D100 produced by Sony, is included in this survey for comparison

purposes. This DAT recorder, which lists for $900, can provide up to 4 hours of stereo recording

on two AA batteries. This DAT device can sample at 48kHz, 44.1kHz or 32kHz, and uses 16 bit

quantization. At a 48kHz sample rate, it has a 20-22 kHz frequency response (within 1 dB),

which is greater than the full range of human hearing (20-20kHz). At 44.1 kHz and 32 kHz

sample rates, it has a 20-14.5 kHz frequency response (within 1 dB). The signal to noise ratio is

87dB, and the total harmonic distortion is 0.008%. The wow and flutter is less then 0.001

percent. All of these specifications are excellent, and stack up favorably against the solid state

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

recorders. DAT tapes are available providing 60 minute and 120 minute recording times. A

digital output is available, but it is not known how easily a digitized recording could be

transferred to a PC using this output. Recordings can be transferred to a PC in real-time using

the Line In/Line Out connections. A microphone must be purchased separately. Further

information on this device may be found at the following URL:

http://www.sonystyle.com/home/item.jsp?hierc=9687&catid=8662&itemid=591&telesale=null&

hidden=null&cps=null&type=s. A related product, the NT-2 Digital Micro Recorder is also

available from Sony. The NT-2 is smaller than the TCD-D100, but it has slightly worse

specifications. Further information on the NT-2 may be found at:

http://www.sonystyle.com/home/item.jsp?hierc=9687&catid=8668&itemid=563&telesale=null&

hidden=null&cps=null&type=s.

2.1.4 Microcassette Recorders

Microcassette and cassette recorders are used by numerous law enforcement agencies. These

devices typically have relatively poor frequency response (250 Hz to 4 kHz for microcassettes,

somewhat better for cassettes), have relatively high wow and flutter (due to the mechanical tape

transport), and have poor signal to noise and distortion characteristics when compared to solid

state recorders. Often they have voice activated recording and automatic level control that

cannot be turned off. In many law enforcement applications, it is an advantage to be able to turn

off voice activated recording and automatic level control. Some advantages of the microcassette

and cassette recorder are they are small, they are low cost, they use batteries that are widely

available, and they use cassettes that are widely available.

The Sony M850V is a typical microcassette recorder. It has a frequency response of 250 Hz to 4

kHz, which is well below the human hearing range of 20 Hz to 20 kHz. It has an 11 hour battery

life, and uses 2 AA batteries. It is relatively small, with dimensions of 4” x 2.25” x 7/8”. It has

voice operated recording and automatic level control. This recorder is monaural, and has its own

built in microphone and speaker. It features two recording speeds. The frequency response

quoted is for the higher recording speed. Further information on this recorder may be found at

the following URL:

http://www.sonystyle.com/home/item.jsp?hierc=9687x8667x8671&catid=&itemid=34003.

2.2 Commercial Audio Recorder Issues

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

One issue (potential shortcoming for law enforcement use) with the flash recorders and MP3

player/recorders is the bandwidth achieved in the audio recording. For the recorders with LP

(long play) mode, relatively low sampling rates are used in recording the data (longer recordings

can be made in a given memory size when lower sample rates are used). Unfortunately, the

Nyquist sampling criteria limits the bandwidth of the recording to one-half of the sampling

frequency. Thus, the audio bandwidths for recordings made in the LP mode are relatively low.

A typical sample rate for LP recording is 8kHz, and, by the Nyquist sampling criterion, the

resulting audio bandwidth must be less than 4kHz (typically 3kHz). This audio quality is

approximately the same as telephone voice quality. The 32kbps ADPCM recording scheme used

by the MP3 player/recorder in Table 2-1 also achieves a telephone voice quality bandwidth of

approximately 3kHz. A somewhat better frequency response is achieved by the SP (standard

play) mode of the flash recorders. Sampling rates used in this mode are 12kHz, and the resulting

audio bandwidth must be less than 6kHz (typically 5kHz). Although these bandwidths are

adequate for speech recognition purposes, they do not compare favorably to the human hearing

bandwidth of approximately 20 kHz, and they may not be suitable for all law enforcement

applications.

Another issue with flash recorders and MP3 player/recorders is the loss in fidelity caused by

compression schemes used by the recorders. The recorders attempt to maximize recording time

for the available memory by compressing the sampled audio using proprietary compression

schemes. The higher compression algorithms (greater than 4:1), which conserve the most

memory space, turn out to be lossy; that is, they degrade the fidelity of the recording. The

32kbps ITU G.711 ADPCM compression used by the MP3 player/recorder in Table 2-1 is a

relatively low loss algorithm. The minidisc recorder uses ATRAC3 compression, which has a

compression ratio of 4.8:1. Manufacturers that use the MP3 compression standard have a

compression ratio of greater than 10:1. The DSS (digital speech standard) compression scheme

used by the Olympus DS2000 stores 120 minutes (7200 sec) of highest quality voice in

16Mbytes of flash. A rough calculation of the seconds of uncompressed speech that can be

stored in 16Mbytes is:

16M bytes x 1sec/12k samples x 1 sample/1 byte = 1333 sec

Comparing the compressed seconds of storage to the uncompressed seconds of storage gives a

compression ratio of 5.4 for DSS. Although playback quality may not be affected significantly

by lossy compression schemes for most purposes, one of the concerns in using nonlinear

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

compression for law enforcement recordings is the legal question that might be raised over the

accuracy and faithfulness of the recording.

A third issue with the commercial audio recorders has to do with dynamic range and signal to

noise ratio of the recorded audio. The 8 bits per sample used in these recorders provides for a

signal to noise ratio that will not exceed 50dB (i.e., 6.02n + 1.76). This signal to noise ratio may

not be adequate for all law enforcement applications. For example, if we try to recover low level

audio that is more than 50dB below some high level audio, it will be buried in noise.

Another issue in using commercial audio recorders for law enforcement purposes is whether or

not to use automatic gain control. It would be desirable to be able to defeat the automatic gain

control feature for some applications.

Another issue is whether or not to use voice activated recording. Voice activated recording

conserves room on the recording medium, and it extends battery life by shutting down the

process of recording the audio onto the storage medium when no audio is present. However, a

threshold must be set to activate the voice recording. If the threshold is set too high, some

weaker signals that are desirable evidence may be missed. So, for recorders that do have voice

activation, it is desirable to be able to turn off the voice activation.

Another issue is storage of original evidence at a reasonable price. Unfortunately, there is often

a significant delay of months or even years before a case comes to trial. It would be costly to

have to remove the recorder from use while waiting on a trial. And downloading the original

recording to a PC may not be accepted as original evidence. The original flash memory module

used to record the audio may be the only recording accepted as original evidence. The ability to

have removable flash memory that can be saved as original evidence is a desirable feature of

flash based audio recorders. Using removable flash memory allows the recorder to continue to

be used (with a new flash module) while the original evidence flash module is saved for trail.

3.0 CURRENT AND PROJECTED STATE OF THE ART IN SOLID STATE

RECORDER TECHNOLOGY AREAS

3.1 Solid State Recorder Block Diagram

Figure 3-1 shows a block diagram of a typical solid state voice recorder. Starting at the top left

of the figure, the audio signal is received by one or more microphones. Next, an amplifier/filter

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

increases the voltage of the signal from the microphone to the correct level for the input to the

analog to digital converter (ADC). Some filtering (removal) of unwanted signals may also occur

in this block. The ADC converts the analog input signal to a digital word that is fed to audio

compression hardware. The audio compression hardware (for example, a DSP) implements an

audio compression algorithm, which reduces the number of bytes needed to store the audio

signal. The resulting compressed audio bytes are saved in flash memory. The flash memory is

removable, for convenient storage of evidence. The user interface is implemented by the DSP

sensing the switch positions on the recorder.

AMPLIFIER/

FILTER ENCODER (ADC)

POWER SUPPLY

(BATTERIES)

MICROPHONE

COMPRESSION

(DSP or ASIC)

REMOVABLE

STORAGE

(FLASH)

OPERATOR

INTERFACE

Figure 3-1. Solid state voice recorder block diagram.

Playback of the audio signal may be provided in a number of ways. Commercial items, such as

the SanDisk ImageMate USB CompactFlash/SmartMedia media reader (cost is approximately

$30), may be used to transfer the compressed audio from the flash memory card to a PC. The PC

would run software to decompress the audio, and play back the result on the PC sound system.

The flash recorder manufacturer could provide custom audio decompression PC software, or, if a

standard compression/decompression algorithm is used, a third party could provide the audio

decompression PC software.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

In the design of the flash based audio recorder, the resulting product is only as good as the worst

individual part. The various parts of the recorder will be discussed in the following sections.

3.2 Microphones

Two major classes of microphones that could be used in flash based audio recorders are dynamic

and electret condenser. The dynamic microphone transforms sound into an electrical signal by

the movement of a diaphragm with a coil of wire attached to it. This coil of wire is located close

to a magnet, and when the diaphragm/coil moves in the magnetic field, a current is produced in

the coil. This current corresponds to the audio signal that moves the diaphragm.

Electret condenser microphones operate somewhat differently. The diaphragm and the “back

plate” in an electret condenser microphone form two surfaces of a capacitor. Either the

diaphragm or the back plate contains a permanently charged electret material. When the

diaphragm moves, the distance between the surfaces of the capacitor changes, inducing a current

that corresponds to the audio input. Since the electret condenser microphone diaphragm does

not have a coil attached to it, it can be fairly light when compared to the dynamic microphone.

As a result, the electret condenser microphone generally has better sensitivity and high frequency

response than a dynamic microphone.

One characteristic of a microphone is its directivity, which is its sensitivity to sound arriving

from different directions. A microphone that picks up sound equally well in all directions has an

“omnidirectional” pattern. A microphone that is more sensitive to sounds in front of the

microphone that behind the microphone is “unidirectional” (cardioid). A microphone that is

sensitive to sounds in front and behind, but not to the sides, is “bi-directional” (noise canceling).

One typical electret condenser microphone is the Panasonic WM-61 series. This back electret

condenser omnidirectional microphone has a frequency response from 20 to 20kHz, a signal to

noise ratio of better than 62dB, and a sensitivity of –35dB (0dB = 1V/Pascal). The WM-61 has a

low power consumption of 0.5 mA at 2V.

For law enforcement applications, the superior frequency response and sensitivity of the electret

condenser microphone is preferred over the dynamic microphone. For monophonic recordings,

an omnidirectional microphone is preferred. For stereo applications, either cardioid or

omnidirectional pattern microphones may be used.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

3.3 Delta Sigma Analog to Digital Converters

In solid state audio recorders, audio signals must be converted from the analog domain to the

digital domain so they can be stored in a digital format in flash memory. This function is

performed by a high quality analog to digital converter (ADC). One type of ADC that is

particularly well suited to this task is the delta sigma ADC. The delta sigma ADC samples the

input waveform at a much higher rate than is normally required (often 128X oversampling is

seen in these devices). Oversampling distributes the quantization noise all the way up to the

sampling frequency, thereby reducing the amount of quantization noise in the audio band. The

delta sigma ADC also uses a noise shaping filter. This noise shaping filter effectively moves

quantization noise from the audio band to higher frequencies. The delta sigma converter then

uses a digital filter to remove the higher frequencies (and quantization noise), and retain the

audio frequencies. The resulting digitized signal from the delta sigma converter has very little

quantization noise, and is highly accurate representation of the input analog waveform.

Delta sigma converters are typically inexpensive, have low power requirements (suitable for a

battery operated voice recorder), and are highly accurate. One device, the CS5333, converts two

inputs (for stereo operation), provides 24 bits of output, requires only 11mW, and costs less than

$5. As seen in the specifications of the CS5333, the current generation of delta sigma analog to

digital converter has more than enough performance to meet law enforcement needs of high

dynamic range and full audio bandwidth, and it is reasonably priced.

Delta sigma ADCs and digital to analog converters (DACs) are used in audio sound cards for

PCs. The demand for these products may roughly be expected to follow the demand for PCs in

the future. Which is to say, the high demand for delta sigma converters (both digital to analog

and analog to digital) in computer audio sound systems makes the continued availability of these

devices highly likely.

3.4 Audio Compression Algorithms

Audio compression algorithms are used in flash based audio recorders to reduce the amount of

flash memory required to record a specified duration of audio. If 20kHz audio is sampled at the

Nyquist rate of 40kHz, then, in the absence of compression, each second of audio requires

40,000 audio samples to be stored in flash memory. A compression algorithm that achieves a

compression ratio of 4:1 would reduce the flash memory storage requirements from 40,000 down

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

to 10,000. A fixed amount of flash memory can store 4 times as much audio when a 4:1

compression algorithm is used.

Audio compression algorithms may be divided into two categories: lossless and lossy. When

recordings made using lossless compression are played back, the original signal is reproduced

exactly, and no compression artifacts are present. When recordings made using lossy

compression are played back, the original signal is not exactly reproduced, but a slightly

degraded version of the original signal is reproduced. Lossless audio compression schemes

typically achieve compression ratios in the range of 1.5:1 to 3:1. Lossy audio compression

schemes typically achieve compression ratios in the range of 4:1 to 12:1 and higher (Windows

Media Audio claims 24:1).

The state of the art lossless audio compression process can be divided into three stages: framing,

decorrelation, and entropy coding. Framing divides the audio signal into equal duration frames.

Optimum duration frames appear to be in the range of 13 to 26ms. Audio signals exhibit a high

degree of autocorrelation; that is, the current sample can be predicted from previous samples. To

take advantage of this characteristic, the original signal is decorrelated (and the correlation

characteristic is remembered). It is more efficient to store the correlation characteristics in the

encoded waveform than it is to store the audio samples. Several techniques are available for

performing decorrelation: coding with linear prediction, coding with approximation, and

transform coding. Once the correlation in the waveform has been removed, the remaining

decorrelated waveform must be encoded. Entropy coding is used for this purpose. Some

standard entropy coding methods include: Huffman coding, run length coding, and Rice coding.

Some representative state of the art lossless audio encoders include the following:

- AudioPAK (integer)

- MUSICompress (fixed point)

- Sonarc (fixed point)

- Shorten (floating point)

- Ogg Squish (floating point)

- LTAC (lossless transform audio compression - floating point)

- Waveform Archiver (floating point)

The objective of the AudioPAK algorithm is to reduce the complexity of implementing lossless

audio compression while maintaining compression ratios that are comparable to the more

complex lossless audio compression algorithms. Notice that the AudioPAK uses integer

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

operations, while the other algorithms mentioned use fixed point or floating point operations.

Much of the material in this section has been derived from: Optimization of Digital Audio for

Internet Transmission by Mat Hans – Georgia Institute of Technology PhD thesis, 1998

(http://users.ece.gatech.edu/~hans/). This thesis describes the AudioPAK algorithm.

Another lossless compression technique worth mentioning is bit plane encoding. With this

technique, a particular bit of each PCM sample is encoded over a frame of samples. This process

is repeated until all bits have been encoded. This technique expects that the most significant bits

of audio PCM samples will not change very often, and can be efficiently run length encoded.

The least significant bit is expected to change frequently, and can use Huffman entropy

encoding.

Before leaving the subject of lossless audio compression, it is interesting that lossless audio

compression can be achieved by using the PKzip (Winzip) algorithm that is so familiar to

today’s computer users. Unfortunately, the PKzip algorithm does not achieve very good

compression ratios for audio files (typically 1.1:1). One reference that discusses PKzip (Winzip)

performance relative to other lossless audio compression techniques, and lossless audio

compression performance in general is “Digital Audio Gets an Audition, Part 1 Lossless

Compression,” EDN, January 4, 2001.

A number of lossy audio compression techniques are available. We will briefly describe two

here: MP3 and ATRAC. These two compression techniques are used in MP3 players and mini

disc recorders respectively.

Although the MP3 players do not use MP3 compression to record audio (they typically use

32kbps ADPCM instead), the compression scheme is one dominant form of lossy audio

compression that is used today (the Soundtainer product mentioned above uses MP3 to record

audio). MP3 stands for MPEG Audio Layer 3 (as opposed to the lower compression MPEG

Audio Layers 1 and 2). MP3 can achieve compression ratios of 10:1 to 14:1 with a bandwidth of

over 15kHz. One method the MP3 algorithm uses to reduce the amount of information to be

encoded (thereby compressing the size of the audio file) is to omit audio that is not perceptible to

humans. One example is called frequency masking. In this situation a loud sound present in one

frequency band masks softer sounds present in an adjacent frequency band. In this instance,

humans will not notice a difference when the soft sounds are completely removed. Similarly,

MP3 observes a minimum audio threshold, and will not record sounds below a certain level at

certain frequencies (2 to 5kHz), since these will not be perceptible to humans. MP3 “borrows”

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

from a “reservoir of bytes” to encode more complex audio, and “replenishes” the reservoir

during less complex audio passages. MP3 uses a discrete cosine transform that has 384

coefficients to decorrelate the audio signal. It then throws away data that would not be noticed

by the listener. Finally, MP3 uses Huffman entropy encoding, once the audio that will not be

encoded has been subtracted from the signal.

ATRAC (Adaptive Transform Acoustic Coding) is the compression technique used in mini disc

recorders. It typically achieves a 5:1 compression ration on CD audio, and, like MP3, it uses a

psychoacoustic model of human hearing to determine what sounds may be subtracted form the

original signal without being detected by human hearing. ATRAC divides the audio frequency

band into 3 subbands (0-5.5kHz, 5.5-11kHz, and 11-22kHz) using Quadrature Mirror Filters

(QMFs – prevents aliasing when reconstructing). A discrete cosine transform is performed on

each subband using an adaptive block length (long or short). Long block lengths provide

superior frequency resolution, but are subject to “pre echo” during “attack” portions of the audio

signal. Short block lengths are used to prevent pre echo. and transforms these subbands into the

frequency domain. Signals that would be masked by psychoacoustic effects are subtracted from

the resulting frequency domain coefficients, and the coefficients are encoded into BFUs (block

floating units). (reference: ATRAC: Adaptive Transform Acoustic Coding for Mini Disc,

Tsutsui et al, 93rd Audio Engineering Society Convention, Oct 1-4, 1992.) A newer version of

ATRAC called is ATRAC3 is now available.

Both MP3 and ATRAC (as well as many other lossy audio compression algorithms – AC3 for

example) use a psychoacoustic model of human hearing to remove signals that would not be

perceived by humans as a method of reducing the amount of audio that must be saved (as a

method of compressing audio). For law enforcement applications, this practice may not be

acceptable in some situations. For example, if a soft sound contains information needed by law

enforcement personnel, and a loud sound “masks” it, the soft sound will be removed from the

encoded audio when either MP3 or ATRAC is used. For this reason, audio compression

algorithms that rely on the psychoacoustic model of human hearing to delete audio signals are

not recommended for law enforcement applications (at least not all law enforcement

applications).

Other lossy audio compression algorithms include:

- AAC (Advanced Audio Coder www.aac-audio.com)

- ATELP (www.softsound.com/ATELP.html)

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

- DTS (www.dtsonline.com)

- ePAC (www.lucent.com/ldr)

- Indeo (www.ligos.com)

- Ogg Vorbis (www.vorbis.com)

- Qdesign (www.qdesign.com)

- Real Audio (www.real.com)

- TAC (kk-research.hypermart.net)

- TwinVQ (sound.splab.ecl.ntt.co.jp/twinvq-e)

- Windows Media Audio (www.microsoft.com/windows/windowsmedia)

A reference that gives an overview of these algorithms and their performance is “Digital Audio

Gets an Audition, Part 2 Lossy Compression,” EDN, January 18, 2001.

One further audio compression algorithm worth mentioning is apt-X 4:1. This algorithm uses

ADPCM to achieve a 4:1 compression ratio, with very little loss in audio quality. This algorithm

uses four frequency subbands, but does not rely on psychoacoustic models of human hearing to

throw away audio information that is not perceptible to humans. More information may be

found on this technique at http://www.aptx.com.

3.5 Audio Compression Hardware

Audio compression algorithms are implemented on audio compression hardware, which includes

Digital Signal Processors (DSPs) and custom Application Specific Integrated Circuits (ASICs).

DSPs are specialized computer chips that have features that facilitate the implementation of

audio compression algorithms. Like any computer, DSPs may be reprogrammed to perform

different functions. ASICs are not reprogrammable. The Field Programmable Gate Array

(FPGA) may be used to develop algorithms that are then readily transferred into an ASIC.

Highly capable, low cost DSPs have become available in the past few years. For example, the

TMS320VC5402 DSP from Texas Instruments is capable of 100 million instructions per second

(MIPS), and has 16K words of on chip RAM, and 4K words of on chip ROM. The cost of this

part is approximately $6 in quantities of 1000. A part specifically designed for low power

consumption, the TMS320VC5502, is also becoming available. It has 32K words of on chip

RAM and 4K words of on chip ROM, and features 400 MIPS performance. The 5502 part will

sell for approximately $10 in quantities of 1000. Both the 5402 and the 5502 are fixed point

processors.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

The trends toward lower core voltages, smaller geometry devices, and higher processing

capabilities in DSPs and ASICs can only benefit flash based audio recorders. The current

capabilities of DSPs like the 5502 are more than adequate for implementing fixed point and

integer lossless audio compression algorithms for flash based audio recorders.

3.6 Flash Memory

Flash memory is used to store the compressed audio in the solid state recorder. Flash memory is

used in cell phones, digital cameras and MP3 players. The cost of the flash memory is the

dominant cost of the recorder. A 16kHz Obviously, any reductions in the cost of flash will

reduce the cost of the flash based audio recorder.

In mid 1998, an Intel 28F640J5 8 M byte flash part cost $65. Today (2002) a comparable part,

the 28F640J3A, costs $13.42, a reduction of nearly 5 times. Perhaps even more important than

the cost of the individual flash chips is the cost of removable flash media. Driven by the

proliferation of digital cameras and MP3 players, the cost of removable flash media has dropped

significantly in the past years. Today’s street prices for SanDisk flash products are as follows:

CompactFlash 1 G Byte: $631

CompactFlash 512 M Byte: $269

CompactFlash 256 M Byte: $115 (if 1000 units are purchased, the cost is $102)

CompactFlash 128 M Byte: $63

Memory Stick 128 M Byte: $70

Secure Digital 256 M Byte: $161

MultiMedia 64 M Byte: $52

Ultra CompactFlash 128 M Byte: $77

Flash memory provides a method of storing digital audio data that is non volatile; that is, data

stored in flash memory is not lost when the power is turned off to the device. Flash memory may

be NAND based or NOR based. NAND based technology is considered well suited for high

capacity data storage applications, such as storage of audio files. Current flash memory for file

storage often uses 2 bit per cell storage, an improvement over the older single bit per cell flash

technology.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Flash memory that uses 0.25, 0.16, and 0.13 micron semiconductor process technology is

currently available, and smaller process technology is being planned. Parts that operate on 3V

and 1.8V are commonplace, and lower voltages are being planned. These developments are

expected to reduce cost for given storage size devices, and lower power consumption, which

would both benefit flash based audio recorders. SanDisk is expecting prices to drop

approximately 30% over the coming year.

3.7 Batteries

Batteries for mobile electronic applications such as digital cameras and MP3 players may be

divided into two groups: rechargeable and non-rechargeable. Within the rechargeable group, the

most popular technologies today are: nickel metal hydride (NiMH) and lithium ion (Li-Ion). In

the non-rechargeable group, the most popular technologies are the alkaline and carbon zinc

batteries.

Nickel metal hydride batteries require recharging more often than lithium ion batteries, but they

cost less than lithium ion batteries. Lithium ion batteries provide a better energy density than

nickel metal hydride batteries. An energy density figure of 75 Watt hours per kilogram is

provided by nickel metal hydride batteries, versus 135 Watt hours per kilogram for lithium ion

batteries. The output voltage of lithium ion batteries is typically higher (3.0V) than the output

voltage of nickel metal hydride batteries (1.2V). When compared to nickel cadmium

rechargeable batteries, both nickel metal hydride and lithium ion batteries offer the advantage of

not having any memory effect. (http://www.nec-

tokin.net/now/english/product/me/chisiki/li3.html).

The alkaline battery in a AA size can provide 3000mAh at 1.5V, and an energy density of 140

Watt hours per kilogram. In comparison, a AA carbon zinc battery in AA size can provide only

950mAh at 1.5V and an energy density of 50 Watt hours per kilogram.

Alkaline and carbon zinc batteries have sloping discharge curves. That is, as the battery is

discharged, the voltage goes down over time. In contrast, the nickel metal hydride and lithium

ion batteries have flatter discharge curves. When these batteries are discharged, the voltage does

not go down over time as much as with the alkaline and carbon zinc batteries.

The popularity of laptop computers, cell phones, cordless phones, digital cameras, MP3 players,

and personal digital assistants has spurred the demand for rechargeable batteries. In 2000, the

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

market for rechargeable batteries was $1.75 billion. This market is projected to grow to $2.19

billion by 2006. The technology that will account for most of the battery demand in 2005 is the

Lithium Ion. Lithium Ion batteries are expected to grow from 25% of the battery market in 1999

to 55% of the battery market in 2005. (source: http://www.eetimes.com/myf00/ao_batt.html)

One emerging battery technology is Lithium Ion Polymer. This battery technology has the

potential to greatly increase the energy density when compared to current Lithium Ion products.

Another Lithium Ion emerging battery technology replaces the cobalt in the battery with a

different cathode material. The problem with cobalt is that it requires protection circuits inside

the battery to prevent thermal runaway when the battery is being charged. One company,

Valence Technology, claims that using Saphion for the cathode will reduce the cost of lithium

ion batteries (http://www.valence.com/saphion.asp).

The development of a low cost, widely available, lithium ion polymer battery with high energy

densities could reduce the size required for batteries in the flash based audio recorder. A reduced

size recorder has obvious advantages for law enforcement purposes. It is uncertain when lithium

ion polymer batteries will reach this stage of development.

4.0 PROJECTED COMMERCIAL SOLID STATE RECORDER PRODUCTS

(IN 2 YEARS)

Solid state recorder products are in a state of rapid development and improvement, with models

constantly being discontinued and replaced by newer, improved models. Since this program and

evaluation of devices began, many of the models initially in the product matrix (see Appendix A)

had to be dropped and replaced by more current models. The trend has been toward

recorders/MP3 players with larger memory capacity and lower costs. This trend is expected to

continue.

But the demand for higher bandwidth portable voice recorders has not been seen yet. There is a

strong demand for MP3 players (i.e., there are lots of MP3 player products being sold), which

feature voice recorders as a secondary feature. And there is a strong demand for voice recorders

used for business dictation applications. But these kinds of voice recorders do not need to have

high bandwidth, and no mass market commercial voice recorder has bandwidths up to 16 kHz or

higher that would be useful for law enforcement applications.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

As removable flash memory cards continue to increase in memory storage space and decrease in

cost, the solid-state MP3 recorder/players may evolve to take advantage of this storage space and

become true music recorders as opposed to simply voice recorders. Commercial motivation may

encourage these recorder/players to take advantage of the 44.1 kHz sampling frequencies

currently used to decompress and playback the MP3 files and begin recording audio files in

stereo with MP3 compression as opposed to simply decompression. These devices could then

compete very favorably with the minidisc recorder/players in the marketplace, being slightly

smaller in size and less power hungry. But the market is not seen for MP3 recorders. Most

consumers are not interested in recording their own music, via a microphone. Instead, they are

interested in transferring music tracks from CDs or from the web to their PC and then storing

them on MP3 players. And even if a MP3 recorder did evolve, the lossy compression used in

MP3 is not always suitable for law enforcement purposes.

The market for high fidelity portable audio recorders would seem to be pretty much the same as

the market for portable digital audio tape (DAT) recorders. Today, this market is a low volume,

relatively high cost niche. For example, the Sony TCD-D100 DAT recorder lists for $900 and it

was difficult to find a dealer that sells this device. It may be possible that DAT will evolve into a

flash based product, but the demand to make it a low cost item sold in large quantities is not

seen.

5.0 AUDIO RECORDER CONCLUSIONS

Desired characteristics of audio recorders for law enforcement purposes are as follows:

- wide and flat frequency response (20-20kHz)

- high signal to noise ratio and dynamic range

- low wow and flutter

- low harmonic distortion

- lossless compression

- defeatable automatic level control

- defeatable voice activated recording

- stereophonic recording

- combined microphone response that is omnidirectional

- record times of at least 60 minutes, with 120 minutes and higher available

- removable media

- low cost media

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

- wide availability of media

- wide availability of batteries

- small size

- low cost

Large volumes are projected in MP3 player recorders, and, to a lesser extent, in solid state voice

recorders. But large volume (low cost) products (current and projected) fall short in several key

areas:

Current and projected future commercial flash recorder products weaknesses:

1. lossy compression

2. poor frequency response

3. poor dynamic range and signal to noise ratio

Current and projected MP3 player voice recorder combination product weaknesses:

1. poor frequency response

2. poor dynamic range and signal to noise ratio

Current and projected mini disc weaknesses:

1. lossy compression

2. Susceptibility to shock and vibration

Many commercial products use automatic level control and voice activated recording features

that cannot be defeated. The ability to defeat these features is desirable for many law

enforcement applications.

To record 120 minutes of uncompressed 16 bit PCM audio with a bandwidth of 16 kHz

(sampling at 32 kHz) requires 460 Mbytes of flash. State of the art lossless compression

algorithms achieve 2:1 to 3:1 compression ratios. So, when lossless compression is used, only

230 Mbytes of flash are needed (instead of 460). Four years ago, the cost of flash was

approximately $8 per Mbyte, making the cost of the flash memory required in the above situation

about $1200. Today, the cost of flash has dropped to less than $0.50 per Mbyte (street price). A

256 Mbyte CompactFlash plug in card can be purchased for $128 or less. So the falling cost of

flash has improved the affordability of the flash based audio recorder.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

$128 is a significant amount of money to spend on a recording medium that may be put on the

shelf while waiting on a trial. But it is much better than the $1200 or so it would have cost 4

years ago. And the expected future improvements in the cost of flash memory will reduce this

$128 to an even lower figure.

Falling prices and larger sizes of flash memory make the solid state recorder a very practical

idea. Improved wow and flutter, increased immunity from shock and vibration, and the

elimination of tape hiss (improved signal to noise ratio) result from the use of flash. But

widespread commercial demand for improved frequency response, high dynamic range, high

signal to noise small solid state recorders is not seen. Instead, business uses of recorders for

dictation purposes, which do not require high bandwidth, high dynamic range, and high signal to

noise ratios are seen as the driving factor in future solid state audio recording products. There is

a market for high bandwidth, high dynamic range, high signal to noise ratio playback products

(MP3 players), but only for playback, not for recording.

To get the characteristics of lossless compression, high bandwidth, high dynamic range, and high

signal to noise ratio, law enforcement personnel must continue to purchase specialty products

such as the FBIRD or the SSABR. No projected future high volume commercial product will

provide all the capabilities of these devices.

It would be possible to make a product that would satisfy today’s law enforcement demands at a

reasonable cost. Appendix B shows the major components of such a product, and that the cost

would be around $140 in parts (excluding circuit boards and cases, and assuming parts are

purchased in quantities of 1000). The major cost factor in this product is the flash memory,

which accounts for $102 out of the $140 total component cost. The product would feature

lossless compression (2:1), a bandwidth of 16kHz, a signal to noise ratio approaching 90 dB, and

over 120 minutes of record time. It would feature removable flash media, and not have

automatic level control or voice activated recording. It would have a size of approximately 9

square inches.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

6.0 COMMERCIAL BODY WIRE PRODUCTS

Law enforcement agencies utilize body-wires for officer security, and to obtain evidence. Audio

quality, transmitted power, and price vary with different systems. Typically, the transmission

range can be between 30 and more than 3,000 feet depending on the environment and the quality

of the equipment. In addition, there are many different frequencies utilized for transmission.

The purpose of the body wire is to transmit audio in the form of a radio signal to be received,

understood and/or recorded at a remote location. The person wearing the body wire can be

moving and turning in locations that range from outside to inside a building and from ground

level to many stories up. While the transmitter is often mobile, the receiver is generally in one

location. In the case of vehicle audio surveillance, both the transmitter and receiver are in

motion, but the transmission distance is generally constant.

The transmitter may be required to cover thousands of feet or a few yards. The different

environments of the signal propagation path will cause different attenuation levels: the signal

will become attenuated and the range, therefore, reduced if it is required to travel through

numerous buildings. Noise conditions, present at the time the audio signal is recorded, will vary

from those of an outdoor, urban environment (which has many possible levels of background

noise) to that of a quiet indoor room.

Throughout this program, data has been collected on body wires that could be used for law

enforcement applications under the conditions described above. A wide variety of body wires

are available. These products are discussed in the following sections.

6.1 Overview of Body Wire Products

Table 6-1 presents a summary of the performance of various kinds of body wires. Three types of

body wires cover the majority of body wire products: Narrow Band FM (NBFM), Digital, and

Spread Spectrum Digital. Actual representative products were evaluated to fill in this table, but

the band names of the products have been omitted. Strengths and weaknesses of each body wire

category are listed in the table.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table 6-1. Body Wire Types and Feature Comparison

Feature NBFM Digital Digital Spread

Spectrum

Voice quality LOW VERY HIGH MODERATE to

VERY HIGH

Transmission Range HIGH MODERATE LOW to

MODERATE

Battery Lifetime MODERATE MODERATE LOW to

MODERATE

Physical Disguise HIGH MODERATE LOW to

MODERATE

Electronic Security LOW MODERATE HIGH

6.1.1 Narrow Band FM Body Wires

Narrow band frequency modulation (FM) body wire transmitters use the output signal of the

microphone to frequency modulate a radio frequency (carrier) to form the transmitted waveform.

This modulation technique is an analog modulation technique, since the microphone signal was

not first digitized before modulating the carrier.

Frequency modulation leaves the amplitude of the carrier constant, but changes the

“instantaneous” frequency of the carrier in accordance with the amplitude of the signal from the

microphone. Loud audio signals from the microphone correspond to relatively large changes in

the frequency of the carrier. Soft audio signals from the microphone correspond to relatively

small changes in the frequency of the carrier. Since FM signals use the frequency instead of the

amplitude of the carrier to carry the audio from the microphone, they are inherently immune to

amplitude noise.

Commercial FM radio stations use a form of FM called wideband FM. In this case, the

frequency of the carrier can change up to 75kHz due to loud audio from the microphone. In

contrast, body wires use narrowband FM. For narrowband FM the frequency deviation caused

by loud audio from the microphone is much less than the wideband case. In the case of

narrowband FM, the frequency of the carrier can change up to 5 or 7kHz.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

6.1.2 Digital Body Wires

A digital body wire passes the output of the microphone through an analog to digital converter

(ADC), the output of which is a series of 1’s and 0’s referred to as bits of digital data. This

digital data then modulates a radio frequency (carrier) using a digital modulation technique.

One example of a digital modulation technique that is commonly used in digital body wires is

phase shift keying (PSK). In the case of phase shift keying, the phase of the carrier is changed

according to whether a 1 or a 0 data bit is being transmitted. For example, transmitting a 0 data

bit could correspond to no change in the phase of the carrier, and transmitting a 1 could

correspond to a 180 degree change in the phase of the carrier. There are many variations on this

simple example of PSK that could be used in body wires. Other digital modulation techniques,

such as differential phase shift keying (DPSK), frequency shift keying (FSK), or amplitude shift

keying (ASK), are also possible to use in digital body wires. A comparison of some of the more

common digital modulation techniques is shown in the table below.

Scheme Bandwidth needed

(rb is the bit rate)

Bit error rate performance

(S/N for 10-4 bit error)

Equipment complexity

ASK Moderate (approx 2rb) Poor (18.33 dB) Minor

FSK High (>2rb) Fair (15.33 dB) Minor

PSK Moderate (approx 2rb) Best (8.45 dB) Major

DPSK Moderate (approx 2rb) Good (9.3 dB) Moderate

Table 6-1. Comparison of Binary Digital Modulation Schemes (from Digital and Analog

Communication Systems by K. Shanmugam)

As seen in the table, the PSK and DPSK techniques achieve the best bit error rate performance.

Digital modulation schemes with better bit error rate performance will require less transmit

power to communicate over a fixed range, which is beneficial for battery life. Or, equivalently, a

system with better bit error rate performance can communicate over a longer range using a fixed

transmit power.

The “S/N” term in the table refers to signal to noise ratio. This term is the ratio of the received

signal power to the received noise power. This ratio is often measured in decibels (dB). The

formula for S/N in dB is 10 x LOG10 (signal power/noise power), where LOG10 is a base 10

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

logarithm. In the table, notice that the ASK modulation takes a S/N of 18.33 dB to achieve a bit

error rate of 10-4. In comparison, PSK modulation only takes a S/N of 8.45 dB to achieve the

same bit error rate. So it takes a lower signal power for PSK than for ASK to achieve a given bit

error rate performance, which is an advantage of using PSK modulation instead of ASK

modulation.

6.1.3 Digital Spread Spectrum Body Wires

The digital spread spectrum body wire passes the output of the microphone through an analog to

digital converter. Next, the resulting digital data is further encoded by another (higher rate)

sequence of 1’s and 0’s referred to as a PN (Pseudorandom Noise) sequence. The resulting high

rate digital sequence is then used to modulate the carrier. This form of spread spectrum is

referred to as “direct sequence” spread spectrum.

The rate of the PN sequence is referred to as the “chip rate,” and the rate of data bits from the

microphone’s analog to digital converter is referred to as the data rate (rb). The processing gain

of the spread spectrum signal is approximately the ratio of the chip rate to the data rate.

The effect of encoding the microphone digital data with the higher rate PN sequence is to spread

the energy of the transmitted signal over a wider band of frequencies than would otherwise be

used. One advantage of spreading the frequencies in this manner is that the signal becomes

harder to detect than non spread signals.

When a direct sequence spread spectrum signal is received, the first operation is to “despread”

the received signal. This dispreading operation is performed by multiplying a time aligned

version of the PN sequence with the PN sequence in the received waveform. As a result of this

despreading, any narrowband interferers present in the received signal will be spread out, and

less energy from the interferer will be passed into the data demodulation process. The amount of

rejection of the narrowband interferers corresponds to the processing gain of the signal. So a

second advantage of a digital spread spectrum body wire is its ability to reject narrowband

interference.

One further possible advantage of direct sequence spread spectrum worth mentioning is its

secure communication capability. It is necessary to know the transmitter’s PN sequence in order

to despread the signal and listen to the audio. Using a long PN sequence, and keeping the PN

sequence confidential can achieve secure communications.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

In addition to direct sequence spread spectrum, another form of spread spectrum, called

frequency hopping, is also possible. Instead of using a PN sequence, frequency hopping spread

spectrum systems change the carrier frequency of the transmitted waveform periodically.

Frequency hopping spread spectrum systems have similar advantages to direct sequence spread

spectrum systems.

6.2 Body Wire Issues For Law Enforcement

When considering acquiring or using a body wire system, the user should be cognizant of six

performance features:

1. Voice Quality of the Received Audio

2. Transmission Range

3. Battery Lifetime

4. Physical Disguise

5. Electronic Security

6. Cost

Understanding the role played by these six attributes will prove to be an asset in determining the

suitability of a body wire system under consideration. Each of the features 1 through 5 is

discussed in this section. The most significant manufacturer specifications for each feature are

provided along with the associated Figures of Merit.

6.2.1 Voice Quality of the Received Audio

Voice quality is a very important aspect of body wire performance. Poor voice quality could

prevent the listener from hearing words in a conversation, from understanding words in a

conversation, or it could prevent the listener from determining which person was speaking in a

conversation. Any of these problems could place the agent in danger, or prevent the collection of

information needed to solve a case.

Voice Quality can be assessed primarily from specifications of AUDIO BANDWIDTH, AUDIO

DYNAMIC RANGE and, if available, AUDIO SIGNAL TO NOISE RATIO.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

AUDIO BANDWIDTH (audio frequency response) is an important measure of voice quality. A

body wire system with the highest audio bandwidth performance will cover the entire range of

frequencies that can be heard by the human ear (20 Hz to 20 kHz). A high quality music

Compact Disc (CD) has a frequency response of 20 Hz to 20 kHz. A body wire system that only

covers the frequency response of a telephone, which is 400 Hz to 4 kHz, would be considered to

have relatively poor audio bandwidth performance. There is clearly a difference between the

sound quality of a voice on a telephone and a music CD. Table 6-2 below presents useful

information for evaluating the specifications and performance of body wire audio bandwidth.

Quality Lower Frequency Upper Frequency

Telephone quality 400 Hz 4 kHz

Adequate 200 Hz 6 kHz

Good 100 Hz 8 kHz

Very Good 100 Hz 12 kHz

Excellent 50 Hz 16 kHz

Superb < 50 Hz > 16 kHz

Table 6-2. Figure of Merit for Body Wire Audio Bandwidth

AUDIO DYNAMIC RANGE (ADR) is another important measure of voice quality. ADR is a

measure of the systems ability to handle loud and soft sounds. It is the ratio of the loudest

undistorted signal that the system can handle compared to its internal noise. Ideally, a body wire

system with the best ADR would have the same dynamic range as the human ear, which has a

dynamic range of over 120 dB. However, contemporary digital recording techniques can only

achieve a dynamic range of about 90 dB.

Table 6-3 shows relative volume levels for different sounds. The levels in dB are relative to the

threshold of hearing that is taken to be 0dB. From the table, it is seen that the audio dynamic

range necessary to capture audio from whispers to a shout must be greater than 72 dB (90-18

dB).

Sound Level (dB)

Threshold of hearing 0

Quiet Whisper at 5 feet 18

Quiet Office 55

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Average Conversational Speech 70

Shout 90

Subway 102

Threshold of Painful Sound 130

Table 6-3. Relative Audio Dynamic Range – Sound Pressure Level

From the above table, figures of merit may be determined for body wire systems. Table 6-4

shows the figures of merit for the audio dynamic range of a body wire system.

Rating Audio Dynamic Range (dB)

Poor < 40

Moderate 60

Excellent > 80

Table 6-4. Figure of Merit for Audio Dynamic Range

Many body wire radio systems do not have sufficient dynamic range to handle full audio sound

levels. Some may be limited to as little as 30-40 dB. When audio dynamic range is limited,

sometimes automatic gain control (AGC) is used to position the dynamic range window in the

most advantageous place to accurately pick up the most critical audio levels. The AGC shifting

of the dynamic range window may produce undesirable audio artifacts. A carefully crafted AGC

will reduce or eliminate these artifacts.

AUDIO SIGNAL TO NOISE RATIO (SNR) is another important measure of voice quality.

SNR is the ratio of the audio signal power to the noise power. Noise, which is undesired audio

that was not present at the transmitter’s microphone, may come from a number of sources.

These sources include the radio frequency energy in the path from the transmitter to the receiver,

and also include noise from the electronics in the transmitter and the receiver. Figures of merit

for SNR in body wires are given in the table below.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Rating Signal to Noise (dB)

Poor < 40

Moderate 45 to 65

Excellent > 80

Table 6-5. Figure of Merit for Audio Signal to Noise Ratio

BIT ERROR RATE (BER) is another specification that affects audio quality. This specification

applies to digital and digital spread spectrum systems, but not to narrowband FM systems. Bit

error rate is the number of bits in the digital stream that have been received with the wrong

value, compared to the total number of bits received.

Each bit in the digital (or digital spread spectrum) body wire received data stream has a value of

1 or 0. These bits taken together in preset groups (usually 8, 16 or 32 bits) form the ‘words’

which correspond to the digital representation of the audio waveform being transmitted. If one

of these bits is somehow assigned the wrong value, the sound from the receiver will be distorted.

The more bits that are assigned the wrong value, the worse the resulting audio.

Typically, bit error rate is expressed as the frequency of a single erroneous bit. For example, a

bit error rate of 10-6 means that for every 1,000,000 bits sent, one of them will be received

incorrectly, and the audio will be distorted for that instant. The table below shows figures of

merit for bit error rates in body wire systems.

Rating Bit Error Rate

Poor 10-4

Good 10-5

Excellent 10-6

Excellent ++ 10-7

Outstanding 10-9

Table 6-6. Figure of Merit for Bit Error Rate

Bit error rate has a relationship to receiver sensitivity. (Sensitivity is the weakest received signal

power that can be successfully received.) In general, receiver sensitivity is influenced by a

change in bit error rate (and vice versa). A receiver with –100dBm sensitivity at a BER of 10-5

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

could also have a sensitivity of –103 dBm at a BER of 10-4. In the latter specification, the audio

is worse, but the apparent range is better when compared to the former specification.

6.2.2 Transmission Range

The ability to receive the body wire signal at relatively long distances from the transmitter

(agent) can be very useful in some law enforcement applications. High ranges allow the receiver

to be located further from the agent, reducing the likelihood of physical discovery of the

operation. In addition, for mobile applications, high ranges reduce the likelihood that an agent

will move out of range of the receiver.

However, high ranges imply high transmit power. And high transmit power would reduce the

electronic security of the system (increase the likelihood that wiretap detection equipment would

see the signal coming from the transmitter). For this reason, the operation should use transmit

power that is sufficient for the range of the operation, but not excessive.

Range evaluation is dependent on two manufacturer specifications: Transmitter (TX) power, and

Receiver (RX) sensitivity. Path loss represents loss in signal power due to the transmission from

body wore to receiver, and is an environmental factor which determines range for a given TX

power and RX sensitivity. Path loss can not be specified by the manufacturer and needs to be

accounted for by the user. There are many environmental factors that will increase path loss

over a specific distance. Urban environments, with buildings and crowds of people may

experience much greater path loss than in open terrain. From specifications of TX output power

and RX sensitivity, the maximum path loss for received audio that can be accommodated by the

system can be calculated.

In general, increasing transmitter output power will increase range for a particular terrain and RX

sensitivity specification. The power should be expressed in mW or dBm (dBm = 10 x log base

10 of signal power in mW). There is no figure of merit for transmit output power since each

operation will accommodate different equipment with different power ratings.

The table below presents some recommended transmit power values for various law enforcement

applications.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Power Level Remarks

< 20 mW Use with caution – do trial run in the actual

environment to be sure the equipment performs

as required

20 mW to 100 mW Short range applications but remain cautious in

urban environment

100 mW to 200 mW Good general purpose use

> 200 mW Good, but size and battery requirements may

be a problem

Table 6-7. Transmit Power Uses

The receiver sensitivity defines the lowest received power level of the transmitted signal that can

be detected by the receiver at its antenna. A signal received at this level should provide audio

output at the receiver. Receiver sensitivity should be quoted for a specific SNR. Sensitivity is

usually given in dBm. Some radio frequency (FM) systems use a receiver sensitivity notation of

microvolts (uV) for a specific SINAD (signal to noise plus distortion).

Typically specifications will be lower (better) for narrow bandwidth signals such as narrowband

FM and higher for wider bandwidth signals such as digital spread spectrum. Note that sensitivity

is stated with negative numbers since the power is less than 1 mW.

System Type Good Receiver Sensitivity (dBm)

FM systems -110 dBm or below

-120 and below is very good

Digital systems -90 to –110 dBm

-103 and below is very good

Table 6-8. Receiver Sensitivity

In addition to transmit power and receiver sensitivity, path loss determines the range of the body

wire system. Path loss is very dependent on physical conditions present in the locale of the

transmitter and receiver and on the carrier frequency. Building structures, the number of people

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

between transmitter and receiver, interfering vehicles, metal wall studs, etc. (the local operating

conditions) will server to attenuate the transmitted signal by varying amounts. It is not

uncommon to see a requirement of a 8-fold increase in required power to double the range.

Engineering studies have shown that in some cases, the attenuation at ground level is so great

that output power must be increased 16 times in order to double the range. The expression often

stated of 4 times the power to double the range is mainly applicable for line of sight conditions.

Terrain is very important when looking at power outputs of different systems when trying to

determine whether the equipment will meet range expectations.

A related concept to path loss is multipath. Multipath effects are due to portions of the signal

arriving at the receiver at different times from the main signal, caused by reflections within the

environment. These multiple signals arriving at the receiver may be highly disruptive to

communications.

6.2.3 Battery Lifetime

Battery related specifications of body wires include maximum and minimum operating DC

voltage and current drain. These specifications have a direct bearing on the type of battery most

suitable for the equipment.

The current drain specification determines the amount of current required to run the equipment.

The lower the current drain, the longer the equipment will run on a battery. Since many battery

manufacturers list the battery capacity in mAh (milli ampere hours), it is quite easy to determine

how long the equipment will run on a given battery. The current drain of the body wire

equipment should be provided in the specifications.

The minimum operating voltage of a body wire is the minimum voltage that the battery must

supply for the equipment to function properly. Generally, if the battery falls below this level, the

equipment will cease operating. There may also be a maximum (not to exceed) voltage.

Voltages beyond this figure will probably damage the equipment. The minimum operating

voltage is often not given, but it is important in determining battery requirements.

In general, the less current consumed by the body wire, the longer the batteries will last. The

lower the minimum operating voltage, the fewer batteries that are needed. The wider the

operating voltage range (maximum voltage – minimum voltage), the longer the system will

operate on a given battery pack.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

NOTE: Always use new batteries. If the batteries have been taken out of their storage package,

don’t use them for field operation.

6.2.4 Physical Disguise

Two physical features are important for body wires: package size and antenna type. Dimensions

should be given for length, width, and thickness. For body wire usage, the transmitter must be as

thin as possible. It is also advantageous to remote the antenna from the transmitter. Being able

to move the antenna away from the transmitter allows a greater choice of concealment options.

Rating Thickness

Not good > 0.5”

Adequate 0.375” to 0.5”

Good 0.25” to 0.375”

Excellent 0.125” to 0.25”

Superb < 0.125”

Table 6-9. Figure of Merit for Size (Thickness)

6.2.5 Electronic Security

Narrowband scanners can easily detect Narrowband FM (NBFM) systems, since most detectors

are of the narrowband sweep type. The fact that the signal is digitized is significant for

electronic security, since it reduces the probability of interception. Digital spread spectrum

systems are most secure.

Detection is defined as the ability of an outside person to discover the presence of the body wire

signal. Detection can be accomplished with frequency counters, spectrum analyzers, or scanning

receivers.

Interception is defined as the ability of an outside person to acquire the body wire signal and

obtain understandable audio. A tunable receiver is necessary for this purpose. Spread spectrum

systems have very good immunity to interception, since it is necessary for the outside person to

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

know the PN spreading sequence used in order to successfully receive the audio signal. If the

PN sequence is kept confidential, randomly selected, and is long enough, it will be very difficult

for an outside person to obtain understandable audio from the signal.

7. CURRENT AND PROJECTED STATE OF THE ART BODY WIRE

TECHNOLOGY AREAS

7.1 Block Diagrams of Typical Body Wire Transmitters

This section will discuss the block diagrams of the digital, digital spread spectrum, and

narrowband FM body wires. The block diagrams are intended to give the reader a general idea

of the types of components used in body wires. Later sections will then briefly describe the state

of the art for some of the key components used in body wires.

Figure 7-1 shows a simplified block diagram of a typical digital body wire transmitter. Starting

at the top left of the figure, the audio signal is received by the microphone. Next, an

amplifier/filter increases the voltage of the signal from the microphone to the correct level for the

input to the analog to digital converter (ADC). Some filtering (removal) of unwanted signals

may also occur in this block. The ADC converts the analog input signal to a digital word. The

digital word output of the ADC is fed into a coding block, which adds bits to the ADC words that

will serve to detect and correct errors at the receiving end of the body wire link. After these error

detection and correction bits are added, the resulting bit stream is differentially encoded for

differential phase shift key (DPSK) modulation. The resulting bit stream is fed to a binary phase

shift keyed (BPSK) digital modulator. (Other digital modulation methods could also be used, but

this particular block diagram uses BPSK). The BPSK digital modulator changes the phase of the

radio frequency (RF) carrier (from the RF synthesizer), according to whether a 0 or 1 bit is input.

The resulting phase modulated carrier then goes to the power amplifier block. The power

amplifier block increases the power of the modulated RF carrier to a level that is suitable for

transmission. The power amplifier output goes to an antenna matching network, which assures

that the power of the amplified phase modulated RF signal from the power amplifier is

efficiently transferred to the antenna. The matching network feeds the antenna, which sends the

signal through the air to the receiver.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Batteries and voltage regulators provide power for the body wire. The battery voltage is applied

to voltage regulators, which provide the voltages needed by various components in the body

wire.

AMPLIFIER/

FILTER VOLTAGE

REGULATOR(S)

MICROPHONE

POWER AMP

MATCHING

NETWORK

ANTENNA

FREQUENCY

SYNTHESIZER

ANALOG TO

DIGITAL

CONVERTER

BPSK

MODULATOR

BATTERIES

ERROR CODING,

DIFFERENTIAL

ENCODING

Figure 7-1. Digital body wire block diagram.

Figure 7-2 shows a block diagram of a digital spread spectrum body wire. The diagram is very

similar to the diagram for the digital body wire, except for the addition of a PN sequence

generator and an exclusive or (XOR) block. The PN sequence generator generates a random

sequence of bits (chips) that is fed to the XOR block. The XOR block combines the PN

sequence with the data bits from the differential encoding block. The resulting bit stream is fed

to the digital modulator (a BPSK modulator is shown).

Adding the PN bit sequence increases the bit rate going into the BPSK modulator, and thereby

increases the bandwidth of the modulated signal around the RF carrier (the bandwidth of a phase

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

shift keyed signal is approximately twice the bit rate). This increased bandwidth can make a

spread spectrum signal more difficult to detect, since the energy of the signal is spread out over a

wider band of frequencies.

AMPLIFIER/

FILTER VOLTAGE

REGULATOR(S)

MICROPHONE

POWER AMP

MATCHING

NETWORK

ANTENNA

FREQUENCY

SYNTHESIZER

ANALOG TO

DIGITAL

CONVERTER

BPSK

MODULATOR

BATTERIES

PN SEQUENCE

GENERATOR

XOR

ERROR CODING,

DIFFERENTIAL

ENCODING

Figure 7-2. Direct Sequence Spread Spectrum body wire block diagram.

Figure 7-3 shows a block diagram of a typical narrowband FM body wire transmitter. The main

difference in this system and the digital body wire is that analog modulation is used instead of

digital modulation. The analog signals from the microphone’s amplifier/filter are fed to the FM

input on the frequency synthesizer, which frequency modulates the carrier. The output of the

frequency synthesizer goes to a power amp. The power amplifier output goes to a matching

network, and the matching network feeds the antenna.

The frequency synthesizer consists of several components: a voltage controlled oscillator (VCO),

a divide by N counter, a phase/frequency detector, and a loop filter. A temperature compensated

crystal oscillator (TCXO) serves as a frequency reference for the frequency synthesizer. The

frequency synthesizer is used in the narrowband FM, the digital, and the digital spread spectrum

body wires.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

AMPLIFIER/

FILTER

BATTERIES

MICROPHONE

POWER AMP

MATCHING

NETWORK

ANTENNA

VOLTAGE

REGULATOR(S)

FREQUENCY

SYNTHESIZER

Figure 7-3. Narrowband FM body wire block diagram.

Please note that many variations on all three of the above block diagrams are possible. The

intent is to give typical block diagrams, and to give the reader a general idea of the types of

components used in body wires.

7.2 Microphones

(See the discussion on microphones in the solid state audio recorder section)

7.3 Analog to Digital Converters

(See the discussion on delta sigma analog to digital converters in the solid state audio recorder

section)

7.4 Frequency Synthesizer

The frequency synthesizer provides the RF carrier used by the transmitter. A typical frequency

synthesizer consists of several components: a temperature compensated crystal oscillator

(TCXO), a phase-frequency detector, a loop filter, a voltage controlled oscillator (VCO), and a

divide by N circuit (prescaler). The phase-frequency detector compares the phase of the divided

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

VCO with the phase of the TCXO. The loop filter filters the output of the phase frequency

detector, and the output of the loop filter is applied to the voltage control input of the VCO. If

the phase of the divided VCO is different than the phase of the TCXO, the voltage applied to the

VCO will change the VCO frequency until the phase of the TCXO is aligned with the phase of

the divided VCO. In this manner, the frequency of the VCO is controlled so that it is N times the

frequency of the TCXO. By adjusting the value of N, it is possible to generate different

frequencies.

Low cost, low power integrated circuits are available to perform one or more of the functions

needed by the frequency synthesizer. For example, the National Semiconductor LMX2346

provides the phase-frequency detector and divide by N functions. It consumes 6mA of current

and costs $2.05 in quantities of 1000. It is available in small surface mount packages including a

0.25” x 0.2” package and an even smaller chip scale package. A very good TCXO part is the

ECS 39SM series made by ECS, Inc. This part consumes 1.5mA at 3.3V and has a very good

frequency accuracy of 1.5 ppm. It is available in a surface mount package that is 0.45” x 0.38”,

and costs $7.70 in quantities of 1000. An example of a VCO that will cover the the 915MHz

ISM band (for a direct conversion transmitter) is the Maxim 2623. This part consumes 9mA at

3.3V, is available in a 3.0mm x 4.9mm (uMax) package, and sells for $1.80 in quantities of 1000.

The loop filter may be constructed from passive components (resistors and capacitors) for only a

few cents in cost and with very small packages.

Future frequency synthesizer components should benefit from the overall trend in electronics

toward smaller die geometries. Smaller geometries may be operated with lower supply voltages,

resulting in lower power consumption. Smaller geometries can also lead to smaller IC sizes or

greater part densities. The use of synthesizer components in high volume cell phone and

cordless phone markets should ensure the continued development and availability of low cost,

power efficient, small size frequency synthesizer components.

7.5 Power Amplifiers

In most body wire designs, the power amplifier consumes more power than any other single

element. For that reason, operating times for the body wire are dictated largely by the power

needed by the power amplifier.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

One of the biggest decisions in selection of a power amplifier is dictated by whether or not a

constant envelope waveform type of modulation is used. If a constant envelope modulation is

used, then one of the more power efficient amplifier classes may be used (Class B, AB, or even

C). In contrast, if a modulation technique is selected that is not constant envelope, then a less

power efficient amplifier class (Class A) must be used.

One problem with using the more power efficient amplifiers is they do not operate in the linear

region, and are subject to spectral regrowth. A current area of research in power amplifiers for

wireless applications is how to improve the spectral regrowth problems in power efficient

amplifiers. Several techniques to prevent spectral regrowth and preserve efficiency are being

investigated. One such technique is to adaptively bias the power amplifier so it operates in the

most efficient region of class A operation all the time. Another technique is to predistort the

waveform, so that it is relatively undistorted after it is amplified by a Class C amplifier.

An example of a state of the art, low cost amplifier for constant envelope waveforms in the

900MHz ISM band is the Maxim MAX2235. It features a +30dBm (1W) power output, 47

percent efficiency, has a footprint of 6.4 x 6.5mm, and sells for $2.07 in quantities of 1000.

The continued growth in wireless commercial applications (such as cell phones, wireless phones,

PCS, Bluetooth, HomeRF, and wireless LANs) is expected to spur future development of more

efficient power amplifiers.

8. PROJECTED COMMERCIAL BODY WIRE PRODUCTS

(IN TWO YEARS)

It can be anticipated that body wire equipment capabilities will undergo a steady change in the next two years. The

forecast is that digital technology will be assume as more prominent role in wireless operations. The benefits of

security and audio quality will become more in demand. The challenge to the designers and manufacturers is to

bring digital equipment into the same range performance standard as analog and still keep costs down. Digital,

because of its additional complexity, is inherently more expensive than analog. Unfortunately, digital operation will

be faced with a range penalty and the way to increase range is to engineer more efficiency and range enhancements

into the digital equipment. This extra engineering comes with an added cost burden. Operational requirements

demand the best quality audio for evidentiary and investigative purposes, which is of course directly in the province

of digital technology. Better education and training is the way around the seemingly contradictory desires of

performance and cost. Properly trained personnel will understand the benefits and drawbacks of digital equipment

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

and will be able to get the results needed in the difficult investigations involving foreign translations and poor audio

environments. Well trained technicians will be able to get good audio at the ranges required, making the change-

over from analog to digital much less painful.

9. BODY WIRE CONCLUSIONS

Body wire equipment is currently available in a wide variety of size, technology and operating lifetime. The old

adage ”You get what you pay for” is ever applicable. Good analog equipment is not cheap, neither are good digital

transmitters and receivers. Cheap equipment manifests itself in shoddy performance and poor reliability, in spite of

claims of high quality . Written specifications can give a distorted picture to the unknowing. The best advice one

can get is to become knowledgeable about the meaning of equipment specifications and their operational impact.

One must evaluate equipment prospects as to performance and operational tradeoffs – then consider cost. It has

been the case that a law enforcement user has said that a certain piece of equipment is the only thing that can be

afforded, only to discover that the product is quite useless. The small savings in equipment cost can cause a much

larger loss of funds when the entire case is destroyed because the jury could not understand the spoken word or the

translator could not properly comprehend the idiomatic speech.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

APPENDIX A

SOLID STATE RECORDER PRODUCT MATRIX

The following spreadsheet contains a complete listing of the data collected on the various

types of recorders investigated. Many of the desired specifications were not available or were

considered too proprietary to release, particularly related to details regarding the type of

encoding used for the voice recording.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products.

Maker Model Size Wt Record

Time Power

Needs Nom.

SNR (dB) Bandwidth Dynamic

Range Cost PC

Interface Stereo/

Mono Voice

Encoding Sample

Freq / Bit

Rate

Memorex MB002 2.17" x

3.58" x

0.59"

3.8 oz 16 min 2 AAA, 5

hr record 39.99 No Mono

Memorex MB005 2.38" x

4.25" x

0.85"

4 oz 32 min 2 AAA, 5

hr record 49.99 No Mono

Netvox V901 85mm x

60mm x

52mm

70 g w/

batt 15 min 2 AAA

(3V), 75

mA record

No Mono 4.8kbps

compress

Netvox V901P 85mm x

60mm x

52mm

70 g w/

batt 60 min 2 AAA

(3V), 75

mA record

No Mono 4.8kbps

compress

Olympus DS150 4.6" x 1.6"

x 0.6" 2.9 oz w/o

batt LP:160

min SP:75

min (8MB

Int)

2 AAA, 10

hr record Line-in:44

Built-in

Mic: 38

LP:300Hz-

3kHz

SP:300Hz-

5kHz

60 179.00 Serial/

USB Mono DSS

(Digital

Speech

Standard)

SP:12kHz,

13.7kbps

LP:8kHz,

6.3kbps

Olympus D1000 4.7" x

1.81" x

0.91"

5.5 oz w/o

batt LP:34 min

SP:16 min

w/ 2MB

card;

LP:72 min

SP:33 min

w/ 4MB

card

2 AA, 8 hr

record +

CR1220 Li

button

Line-in:44

Built-in

Mic: 38

LP:200Hz-

2kHz

SP:200Hz-

5kHz

55 214.00 Laptop/

Adapter

Card

(PCMCIA)

Mono SCVA

(Silent

Compress

Voice

Activ)

SP:12kHz

LP:8kHz

Olympus V90 4.5" x 1.5"

x 0.5" 1.6 oz w/o

batt LP:90 min

SP:33 min 1 AAA, 10

hr record Built-in

mic: 41 LP:300Hz-

1.7kHz

SP:300Hz-

3.5kHz

48 108.00 No,

Headphon

e Jack

Only

Mono

Olympus VN90 4.6" x 1.6"

x 0.6" 2.3 oz LP:90 min

SP:33 min 2 AAA, 17

hr record Built-in

mic: 41 LP:300-

1.7kHz

SP:300-

3.5kHz

48 93.00 No,

Headphon

e Jack

Only

Mono

Olympus VN180 4.6" x 1.6"

x 0.6" 2.3 oz LP:180

min SP:66

min

2 AAA, 17

hr record Built-in

mic: 41 LP:300Hz-

1.7kHz

SP:300Hz-

3.5kHz

48 119.00 No,

Headphon

e Jack

Only

Mono

Panasonic RR-

QR240 2.2" x 3.5"

x 0.5" 2 oz LP:240min

SP:120

min HQ:60

min

2 AAA

(3V), 30 hr

record

37 (Built-in

Mic, HQ

mode)

HQ:450Hz-

5.0kHz 146.00 No,

Earphone

Out Only

Mono

Panasonic RR-QR80 2.2" x 3.5"

x 0.5" 2 oz LP:60min

SP:30 min

HQ:15 min

2 AAA

(3V), 30 hr

record

37 (Built-in

Mic, HQ

mode)

HQ:450Hz-

5.0kHz 92.00 No,

Headphon

e Jack

Only

Mono

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns).

Maker Model Time/

Date

Stamp

Mic

Ext/Int Removable

Memory? Memory

Size

(MB)

Notes URL

Memorex MB002 No Int Built in Flash VOR capable http://store.yahoo.com/igadget/digvoicrec1.html

Memorex MB005 No Int Built in Flash http://store.yahoo.com/igadget/digvoicrec1.html

Netvox V901 No Int Built in Flash 4 http://www.netvox.com.tw/english/vrecorder.htm

Netvox V901P No Int Built in Flash 16 http://www.netvox.com.tw/english/vrecorder.htm

Olympus DS150 Yes Both Built in Flash 8 VOR capable. Hi/Lo

Mic. Pkg w/ ViaVoice

software for $220.

http://www.zap1.com/comparisons.html

Olympus D1000 Intel

Removable

Flash Memory

Cards: 2, 4,

8MB available

8 8MB cards available

(SP:72 min

LP:148min). VOR

Capable. Pkg w/

ViaVoice software for

$289.99. Opt Flash

Card Reader/ Writer

for PC.

http://www.zap1.com/comparisons.html

Olympus V90 No Int Built in IC VOR Capable. Hi/Lo

Mic http://www.zap1.com/comparisons.html

Olympus VN90 No Both Built in IC VOR Capable. Hi/Lo

Mic http://www.zap1.com/comparisons.html

Olympus VN180 No Both Built in IC VOR Capable. Hi/Lo

Mic http://www.zap1.com/comparisons.html

Panasonic RR-

QR240 Yes Both Built in Flash 32 VOR Capable. Hi/Lo

Mic http://www.prodcat.panasonic.com/shop/product.asp?sku=RR-

QR240&CategoryID=225

Panasonic RR-

QR80 Yes Both Built in Flash 8 Same as RR-QR240

but less memory http://www.prodcat.panasonic.com/shop/product.asp?sku=RR-

QR80&CategoryID=225

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).

Maker Model Size Wt Record

Time Power

Needs Nom.

SNR (dB) Bandwidth Dynamic

Range Cost PC

Interface Stereo/

Mono Voice

Encoding Sample

Freq / Bit

Rate

Samsung Voice Pen

SVR-P220 6" x 0.65"

diam 2 oz LP:138min

SP:70min 1 AAA, 8

hr record Built-in

mic: 40 500Hz-

3.5kHz 229.00 Line Out

Jack Mono ADPCM

Samsung Voice Pen

SVR-P700 5.8" x 0.7"

diam 2 oz 70 min 1 AAA, 4

hr record Built-in

mic: 40 100Hz-4kHz 185.00 Line Out

Jack Mono ADPCM

Samsung Voice

Stick SVR-

S820

102mm x

36mm x

17mm

64 g w/

batt LP:502min

SP:233mi

2 AAA, 10

hr record 500Hz-

3.5kHz 225.00 Line Out

Jack Mono SP:9.5kbp

LP:4.7kbp

Samsung Voice

Stick SVR-

B410

4.75" x 1"

x 0.5" 1.5 oz LP:250min

SP:115mi

2 AAA, 8

hr record 500Hz-

3.5kHz 160.00 Line Out

Jack Mono

Samsung Digital

Recorder

SVR-N200

3.5" x 2.1"

x 0.9" 2 oz LP:119min

SP:59min 2 AAA, 10

hr record 500Hz-

3.5kHz 99.00 Line Out

Jack Mono

Sony ICD-R100 0.5" x 4" x

1.75" 68g w/

batt LP:150min

SP:64min 2 AAA

(3V), 19 hr

record

SP:280Hz-

4.8kHz

LP:240Hz-

3.2kHz

169.95 Parallel Mono ICS (Sony

ADPCM) SP:11kHz

LP:7kHz

Sony ICD-

R100PC 0.5" x 4" x

1.75" 68g w/

batt LP:150min

SP:64min 2 AAA

(3V):19 hr

record

SP:280Hz-

4.8kHz

LP:240Hz-

3.2kHz

199.95 Parallel Mono ICS (Sony

ADPCM) SP:11kHz

LP:7kHz

Sony ICD-70PC 0.938" x

3.375" x

2.375"

1.8 oz w/o

batt LP:24min

SP:16min 2 AAA

(3V) 179.95 Parallel Mono ICS (Sony

ADPCM)

Sony ICD-35 0.875" x

3.375" x

2.125"

2 oz w/o

batt LP:32min

SP:16min 1 AAA

(1.5V), 6

hr record

79.99 No Mono ICS (Sony

ADPCM) SP:8kHz

Sony ICD-37 0.875" x

3.375" x

2.125

2.75 oz

w/o batt 45min 1 AAA

(1.5V), 5

hr record

280Hz-

2.8kHz 99.95 No Mono MSV or

ICS (Sony

ADPCM)

6.5kHz

Sony ICD-55 2.125" x

3.375" x

0.875"

2 oz w/o

batt LP:64 min

SP:32 min 1 AAA

(1.5V), 6

hr record

99.99 No Mono ICS (Sony

ADPCM) SP:8kHz

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).

Maker Model Time/

Date

Stamp

Mic

Ext/Int Removable

Memory? Memory

Size

(MB)

Notes URL

Samsung Voice

Pen

SVR-

P220

No Int Built in

Flash 16 10 levels

of volume

control

(digital).

Output to

PC not

usable for

speech-

to-text

programs.

http://www.zap1.com/comparisons.html

Samsung Voice

Pen

SVR-

P700

No Int Built in

Flash 8 10 levels

of volume

control

(digital).

Output to

PC not

usable for

speech-

to-text

programs.

http://www.zap1.com/comparisons.html

Samsung Voice

Stick

SVR-

S820

No Both Built in

Flash 16 10 levels

of volume

control

(digital).

VOR

Capable

http://www.zap1.com/comparisons.html

Samsung Voice

Stick

SVR-

B410

No Both Built in

Flash 18 10 levels

of volume

control

(digital).

VOR

Capable

http://www.zap1.com/comparisons.html

Samsung Digital

Recorder

SVR-

N200

No Both Built in

Flash 18 http://www.zap1.com/comparisons.html

Sony ICD-

R100 Yes Both Built in IC

Flash 16 VOR

capable,

Hi/Lo Mic,

same as

ICD-R100

PC but

w/o PC

Interface

pkg

http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

Sony ICD-

R100PC Yes Both Built in IC

Flash 16 VOR

Capable,

Hi/Lo Mic,

Hold

Switch

http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

Sony ICD-

70PC Yes Both Built in IC

Flash 4 VOR

Capable,

Hi/Lo Mic,

Min

Record

Segment

4 sec,

Hold

Switch

http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

Sony ICD-35

No Built in IC

Flash 4 http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

Sony ICD-37 Yes Int Built in IC

Flash Hi/Lo Mic,

Hold

Switch

http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

Sony ICD-55 No Built in IC

Flash 8 http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).

Maker Model Size Wt Record

Time Power

Needs Nom.

SNR (dB) Bandwidth Dynamic

Range Cost PC

Interface Stereo/

Mono Voice

Encoding Sample

Freq / Bit

Rate

Sony ICD-67 2.125" x

3.375" x

0.875"

2.75 oz

w/o batt 180 min 1 AAA, 5

hr record 280Hz-

2.8kHz 129.95 No Mono ICS (Sony

ADPCM) 6.5kHz

Sony ICD-V21 2.125" x

3.375" x

0.875"

2.75oz 10 min

Max 1 AAA, 6

hr record 89.95 No Mono ICS (Sony

ADPCM)

Sony ICD-MS1 1.75" x

4.25" x

0.667"

3.1 oz (w/

batt) LP:131

min (8kHz

samp)

SP:63 min

(11kHz

samp) w/

16MB

Stick

2 AAA

(3V), 5 hr

record

SP:240Hz-

4.8kHz

LP:240Hz-

3.2kHz

299.95 Line Out

Only,

Parallel

port PC-

card

reader or

PCMCIA

card

adapter

available

for Stick

Media

Mono MSV

(Sony

ADPCM)

SP:11kHz

LP:7kHz

Sillacom Clue 240 5.1" x 1.2"

x .65" 2 oz LP:233

min

SP:116

min

2 AAA 129.00 Line Out

Jack Mono

Sillacom Clue 480 5.1" x 1.2"

x .65" 2 oz LP:506

min

SP:231

min

2 AAA 150.00 Line Out

Jack Mono

Sillacom Clue 560 5.1" x 1.2"

x .65" 2 oz LP:556

min

SP:255

min

2 AAA 165.00 Line Out

Jack Mono

Voice-It VT-90 3.5" x

2.25" x

0.33"

2 oz 1.5 min 4 CR2025

Lithium

Cells

39.00 No Mono

Voice-It VT-300 3.5" x

2.25" x

0.5"

2 oz 5 min 1 AAA 55.00 No Mono

Voice-It VT-700 3.5" x

2.25" x

0.5"

2 oz LP:22 min

SP:16 min

HQ:12 min

1 AAA No Mono

Voice-It VR-1000 4.75" x

2.25" x 1" 3.5 oz 50 min w/

built-in

memory,

extra 50

min w/

memory

card

2 AAA 118.00 Serial or

USB Mono

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).

Maker Model Time/

Date

Stamp

Mic

Ext/Int Removable

Memory? Memory

Size

(MB)

Notes URL

Sony ICD-

67 Yes Int Built in IC

Flash Hi/Lo Mic,

Hold Switch http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

Sony ICD-

V21 No Built in IC

Flash http://www.sony.com/

Sony ICD-

MS1 Yes Both Yes,

Memory

Stick media

8MB to

64MB

Memory

Stick

Media

(256MB

under

develop-

ment)

Voice files

converted to

16-bit WAV

files in PC,

VOR

capable,

Hi/Lo Mic,

Write Protect

Switch on

Back,

approx. 1hr

voice record

for every 16

MB, rated

"Best

Performance"

by Dragon

Speech

Recognition

Software

evaluation

http://www.sony.com/

Sillacom Clue

240 Built in IC http://www.zap1.com/comparisons.html

Sillacom Clue

480 Built in IC http://www.zap1.com/comparisons.html

Sillacom Clue

560 Built in IC http://www.zap1.com/comparisons.html

Voice-It VT-90 Built in IC http://www.zap1.com/comparisons.html

Voice-It VT-

300 Built in

Flash http://www.zap1.com/comparisons.html

Voice-It VT-

700 Built in

Flash http://www.smoltz.com/

Voice-It VR-

1000 Both, Built

in Flash

plus

memory

card slot

Has slot for

additional

SSFDC

memory card

http://www.smoltz.com/

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).

Maker Model Size Wt Record

Time Power

Needs Nom.

SNR (dB) Bandwidth Dynamic

Range Cost PC

Interface Stereo/

Mono Voice

Encoding Sample

Freq / Bit

Rate

Voice-It VX-1200 3.5" x 2.5"

x 0.75" 2 oz 12 min 1 AAA 71.00 No Mono

Voice-It VX-3400 3.5" x 2.5"

x 0.75" 2 oz LP:34 min

SP:23 min

HQ:17 min

1 AAA 79.00 No Mono

Voice-It VTR-3200 4.75" x

2.25" x

1.0"

3.5 oz LP:74 min

SP:55 min

HQ:40 min

2 AAA, 10

hr record 200.00 Serial,

16.7-33.3

kbps

Mono LP:6kHz

SP:8kHz

HQ:11kHz

Voice-It VM-15 4.24" x

2.25" x

0.75"

3.8 oz 22 min AAA 88.00 No

Voice-It VM-30 4.24" x

2.25" x

0.75"

3.8 oz 45 min AAA 98.00 No

Univex SPD25U/

100U

Voica

digital

recorder

113mm x

55mm x

14mm

58g 25-100

min (2 to

8 MB)

2 AAAA 289.00 Yes

8-hour

Voice

Recorder

4" x 1.375" 502 min 2 AAA, 10

hr record 199.95 Yes

MP3

Creative

Labs NOMAD

64 85mm x

58mm x

17mm

64 g w/o

batt 120min

record

time

2 AAA (5

hrs play

time)

>90 dB 20Hz -

20kHz MP3 202.95 Parallel

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).

Maker Model Time/

Date

Stamp

Mic

Ext/Int Removable

Memory? Memory

Size (MB) Notes URL

Voice-It VX-1200 Built in

Flash ? http://www.zap1.com/comparisons.html

Voice-It VX-3400 Built in

Flash ? http://www.zap1.com/comparisons.html

Voice-It VTR-

3200 Yes Both Both, 4MB

Int Flash,

expandable

w/ 2/4/8MB

Cards

4 Int Flash,

2/4/8 Cards HQ mode

recommended

for voice-to-

text apps. Slot

for additional

SSFDC

2/4/8MB 3.3V

SmartMedia

memory card.

Voice stored

on built-in and

card memory

w/ approx. 20

min for every

2MB in HQ

mode. This

model used

by Dragon

Naturally

Speaking

voice-to-text

software

package. SDK

kit available.

No insert

message

capability.

http://www.zap1.com/comparisons.html

Voice-It VM-15 Built in ? Automatic

phone dialing http://www.zap1.com/VM-30homepage.html

Voice-It VM-30 Built in ? Automatic

phone dialing http://www.zap1.com/VM-30homepage.html

Univex SPD25U/

100U

Voica

digital

recorder

Built in? 2 to 8 Memory size

from 2MB to

8MB

http://www.scandy.com/univex/

8-hour

Voice

Recorder

Built in

Flash 16 Voice

activated?

Has 16MB

flash memory

http://www.lifestylefascination.com/

MP3

Creative

Labs NOMAD

64 Both, Built

in Flash

plus

Smartmedia

Flash slot

32 Int, 32

Smartmedia

Cards

MP3

Player/Voice

Recorder. 1

memory card

slot. 32MB

built in with

32MB (max)

removable

SmartMedia

Flash card.

http://www.egghead.com/category/inv/00057584/02289391.htm

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).

Maker Model Size Wt Record

Time Power

Needs Nom.

SNR (dB) Bandwidt

h Dynami

c Range Cost PC

Interface Stereo/

Mono Voice

Encoding Sample

Freq / Bit

Rate

Creative Labs NOMAD II 65mm x

93mm x

21mm

88 g

w/o batt Up to

240min

record time

on 64MB

SmartMedia

1 AA, 1.5V

(10 hrs play

time)

>90 dB 20Hz -

20kHz

MP3

399.95 USB or opt.

Docking

station

Proprietar

y G.721 4-

bit

ADPCM

@ 32kbps

8kHz, 16-

bit record

prior to

ADPCM

encoding

Creative Labs NOMAD II

MG 58mm x

90mm x

18mm

77.1 g

w/o batt Up to

240min

record time

on 64MB

built-in

memory

2 AAA (10

hrs play

time)

>90 dB 20Hz -

20kHz

MP3

799.99 USB via

Docking

station

Proprietar

y G.721 4-

bit

ADPCM

@ 32kbps

8kHz, 16-

bit record

prior to

ADPCM

encoding

eGO i2GO 2.75" x

1.25" x

4.5"

7 oz 64MB

(240min),

96MB,

170MB,

340MB

2 AA 90dB 20 - 15kHz 219 - 399 USB

Varo Vision VaroMan 130min

Voice 1 AA, 1.5V

(12 hrs play

time)

90dB Parallel ADPCM

Voice

Varo Vision VaroMan II 130min

Voice 2 AAA 90dB USB ADPCM

Voice

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).

Maker Model Time/

Date

Stamp

Mic

Ext/Int Removable

Memory? Memory

Size (MB) Notes URL

Creative

Labs NOMAD

II Removable

SmartMedia

only

64 Max "SDMI

compliant".

Uses

removable

flash memory

cards (64 MB

max). Has

FM Tuner.

Plays MP3,

WMA format

music.

http://www.layer3.org/devices/portables.html

Creative

Labs NOMAD

II MG Both, Built

in Flash

plus

Smartmedia

Flash slot

64 Int,

16/32/64

Smartmedia

Cards

"SDMI

compliant".

64MB built-in

int. memory

plus

removable

SmarMedia

Card slot (64

MB max).

Has FM

Tuner. Plays

MP3, WMA

format music.

http://www.layer3.org/devices/portables.html

eGO i2GO Both, Built

in Flash

plus Flash

card slot

plus ext

hard drive

capability

64, 96,

170(HD),

340(HD)

MP3 Player

with several

memory

options in the

form of

compact flash

cards.

Approximately

1MB for 4

minutes of

recording

http://www.layer3.org/devices/portables.html

Varo

Vision VaroMan Int Both, Built

in Flash

plus

Smartmedia

Flash slot

32 Int,

16/32

Smartmedia

Cards

MP3 Player &

Voice

Recorder.

32MB =

130min voice

recording

time. Built-in

mic. Built-in

32MB,

expandable

by 16/32MB

SmartMedia

Card.

http://www.varovision.com/sub1/vman.html

Varo

Vision VaroMan

II Int Both, Built

in Flash

plus

Smartmedia

Flash slot

32/64 Int,

16/32

Smartmedia

Cards

MP3, MS

Audio (WMA)

Player &

Voice

Recorder.

32MB =

130min voice

recording

time. Built-in

mic. Built-in

32/64MB,

expandable

by 16/32MB

SmartMedia

Card.

http://www.varovision.com/sub1/vman.html

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).

Maker Model Size Wt Record

Time Power

Needs Nom.

SNR (dB) Bandwidt

h Dynami

c Range Cost PC

Interface Stereo/

Mono Voice

Encoding Sample

Freq / Bit

Rate

Varo Vision VaroMan

Plus 170min

Voice on

40MB Clik!

disk

LiIon

Recharge

(12 hr play

time)

90dB Parallel,

USB

optional

ADPCM

Voice

Varo Vision VaroMan

Super

Sensory

Science raveMP

2000 2.67" x

3.7" x

.67"

70g,

w/o batt 120min

Voice on

32MB built-

in memory

only

1 AA, 1.5V

(10 hrs play

time)

70dB 20Hz -

20kHz 50.00 Parallel (up

to 150kbps

R/W)

Mono

Voice

Record

ADPCM

Voice,

MP3

Music

Voice:

LP:33kbps/

8kHz

SP:66kbps

/ 16kHz

HQ:132kbp

s/ 32kHz

Sensory

Science raveMP

2100 2.67" x

3.7" x

.67"

70g,

w/o batt 240min

Voice on

64MB built-

in memory

only

1 AA, 1.5V

(10 hrs play

time)

70dB 20Hz -

20kHz 189.99 Parallel (up

to 150kbps

R/W)

Mono

Voice

Record

ADPCM

Voice,

MP3

Music

Voice:

LP:33kbps/

8kHz

SP:66kbps

/ 16kHz

HQ:132kbp

s/ 32kHz

Sensory

Science raveMP

2200 2.26" x

3.29" x

.68"

74g,

w/o batt 240min

Voice on

64MB built-

in memory

only

1 AA, 1.5V

(10 hrs play

time)

90dB 20Hz -

20kHz 264.94 USB (up to

350kbps

R/W)

Mono

Voice

Record

ADPCM

Voice,

MP3

Music

Voice:

32kbps/

8kHz

Sensory

Science raveMP

2300 2.8" x

4.8" x

.8"

7.4 oz 150min

mono Voice,

75min

stereo

Music on

40MB Clik!

disk

LiIon

Recharge

(12 hr play

time)

90dB 20Hz -

20kHz 299.00 USB (up to

350kbps

R/W), Clik!

Disc (up to

1Mbps)

Mono

Voice

Record

ADPCM

Voice,

MP3,

Microsoft

WMA4,

AAC

Music

Voice:

LP:33kbps/

8kHz

SP:66kbps

/ 16kHz

HQ:132kbp

s/ 32kHz

Audio Request Ondigo 66mm x

90mm x

18mm

4 hrs Max 2 AAA (10

hrs play

time)

90dB 249.95 Parallel

(2Mbps

max)

ADPCM

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).

Maker Model Time/

Date

Stamp

Mic

Ext/Int Removable

Memory? Memory

Size (MB) Notes URL

Varo

Vision VaroMan

Plus Int Removable

40 MB Clik

Discs Only

40 MP3, MS

Audio

(WMA)

Player &

Voice

Recorder.

Clik! Disc

only, no

internal

memory. All

Clik! disc

drives

reportedly

produce an

audible hum

when

operating

(MP3.com

review).

http://www.varovision.com/sub1/vman.html

Varo

Vision VaroMan

Super Not yet

available. http://www.varovision.com/sub1/vman.html

Sensory

Science raveMP

2000 Yes Int,

Line In Both, Built

in Flash

plus Flash

slot

32 Int,

16/32 Flash

Cards

MP3 Player

with 32MB

built in

memory

(expandable

to 64MB w/

32MB Flash

Memory

Card) and

built in mic

http://www.layer3.org/devices/portables.html

Sensory

Science raveMP

2100 Yes Int,

Line In Both, Built

in Flash

plus Flash

slot

64 Int,

16/32 Flash

Cards

MP3 Player

with 64MB

built in

memory

(expandable

to 96MB w/

32MB Flash

Memory

Card) and

built in mic

http://www.layer3.org/devices/portables.html

Sensory

Science raveMP

2200 No Int Both, Built

in Flash

plus Flash

slot

64 Int,

16/32/64

Flash Cards

MP3 Player

with 64MB

built in

memory

(expandable

to 126MB

w/ 64MB

SmartMedia

Card) and

built in mic

http://www.layer3.org/devices/portables.html

Sensory

Science raveMP

2300 Int 40 MB Clik

Discs 40 MP3/WMA

Player with

0MB built in

memory

and built in

mic; ZDNet

review

claims

"muted &

fuzzy" voice

record

http://www.layer3.org/devices/portables.html

Audio

Request Ondigo Both, Built

in Flash

plus

Smartmedia

Flash slot

64 Int,

SmartMedia

Slot

MP3 player,

FM tuner,

250 number

phone

directory,

SmartMedia

expansion

slot.

http://www.layer3.org/devices/portables.html

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).

Maker Model Size Wt Record

Time Power

Needs Nom.

SNR (dB) Bandwidt

h Dynami

c Range Cost PC

Interface Stereo/

Mono Voice

Encoding Sample

Freq / Bit

Rate

JazPiper MV32P 66mm x

90mm x

18mm

74g 32MB or 2

hrs (exp to

64MB)

2 AAA (10

hrs play

time)

90dB 169.00 Yes

JazPiper MVR64P 66mm x

90mm x

18mm

74g 64MB 249.00 Yes

D-Link DMP-100 85mm x

62mm x

17.5m

62g

(w/o

batt)

Over 120

min Voice 2 AAA, 3V

(10 hrs play

time)

90dB 20Hz -

20kHz 139.00 Parallel Mono

Voice

Record

24kbps -

256kbps

D-Link DMP-110 89mm x

65mm x

17mm

80g

(w/o

batt)

Over 120

min Voice 2 AAA, 3V

(10 hrs play

time)

90dB 20Hz -

20kHz 149.00 USB

(12Mbps

transfer)

Mono

Voice

Record

24kbps -

256kbps

D-Link DMP-120 89mm x

65mm x

17mm

80g

(w/o

batt)

Over 120

min Voice 2 AAA, 3V

(10 hrs play

time)

90dB 20Hz -

20kHz 199.00 USB

(12Mbps

transfer)

Mono

Voice

Record

24kbps -

256kbps

Pine D'Music SM-

320V 63mm x

85mm x

17.5m

62g

(w/o

batt)

135 min

Max Voice 2 AAA, 3V

(10 hrs play

time)

90dB 20Hz -

20kHz 169.99 Parallel Mono

Voice

Record

MP3? 24kbps -

256kbps

Samsung YP-E32

(Yepp32) 65mm x

87mm x

17.2m

75g

(w/o

batt)

32MB/128

min 2 AAA, 3V

(10 hrs play

time)

90dB 20Hz -

20kHz 149.99 Parallel/

USB opt Mono

Voice

Record

ADPCM

Samsung YP-E64

(Yepp64) 65mm x

87mm x

17.2m

75g

(w/o

batt)

64MB/256

min(?) 2 AAA, 3V

(10 hrs play

time)

90dB 20Hz -

20kHz 229.99 Parallel/

USB opt Mono

Voice

Record

ADPCM

AudioVox MP3000 3.3" x

2.5" x

0.7"

2 oz 64MB +

64MB MMC 2 AAA (14

hrs record

time)

149.99 Parallel

MINIDISC

Sony MZ-R90 3.125"

2.875"

0.6875"

3.7 oz

(w/o

batt)

74min

stereo,

148min

mono

1 AA (16.5

hr play

time) or 1

NH-14WM

NiMH (12

hr play

time)

20-20kHz 399.95 PCLink opt

(USB to

Optical

Digital Line

In); Line

Out to PC;

Both Real-

Time Only

Both ATRAC 44.1kHz

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).

Maker Model Time/

Date

Stamp

Mic

Ext/Int Removable

Memory? Memory

Size (MB) Notes URL

JazPiper MV32P Both ? MP3 player. http://www.layer3.org/devices/portables.html

JazPiper MVR64P Both ? Same as

MV32P

except has

64MB built

in, and has

FM tuner

and "3D

Audio".

http://www.layer3.org/devices/portables.html

D-Link DMP-

100 Int Both, Built

in Flash

plus

Smartmedia

Flash slot

32 Int,

16/32

Smartmedia

Cards

32 MB built

in Flash

Memory.

Smartmedia

slot allows

expansion

by 32 MB.

http://www.dlink.com/products/DigitalHome/DigitalAudio/

D-Link DMP-

110 Int Both, Built

in Flash

plus 3.3V

Smartmedia

Flash slot

32 Int,

16/32

Smartmedia

Cards

32 MB built

in Flash

Memory.

Smartmedia

slot allows

expansion

by 32 MB.

http://www.dlink.com/products/DigitalHome/DigitalAudio/

D-Link DMP-

120 Int Both, Built

in Flash

plus 3.3V

Smartmedia

Flash slot

64 Int,

16/32/54

Smartmedia

Cards

64 MB built

in Flash

Memory.

Smartmedia

slot allows

expansion

by 64 MB.

http://www.dlink.com/products/DigitalHome/DigitalAudio/

Pine D'Music

SM-

320V

No Int Both, Built

in Flash

plus 3.3V

Smartmedia

Flash slot

32 Int,

16/32

Smartmedia

Cards

Smartmedia

slot allows

expansion

by 32 or 64

MB to 32

MB built in;

10 MHz/8bit

CPU

http://www.layer3.org/devices/portables.html

Samsung YP-E32

(Yepp32) Int Both http://www.layer3.org/devices/portables.html

Samsung YP-E64

(Yepp64) Int Both http://www.layer3.org/devices/portables.html

AudioVox MP3000 Both http://www.layer3.org/devices/portables.html

MINIDISC

Sony MZ-R90 Yes Ext Minidiscs 74/148 min Mini-disc

player/

recorder.

http://www.sony.com/

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).

Maker Model Size Wt Record

Time Power

Needs Nom.

SNR (dB) Bandwidt

h Dynami

c Range Cost PC

Interface Stereo/

Mono Voice

Encoding Sample

Freq / Bit

Rate

Sony MZ-R70 3.1875"

x 3" x

4 oz

(w/o

batt)

74min

stereo,

148min

mono

1 AA (17 hr

play time)

or 1 NC-

WMAA

NiMH (6.5

hr play

time)

20-20kHz 279.95 PCLink opt

(USB to

Optical

Digital Line

In); Line

Out to PC;

Both Real-

Time Only

Both ATRAC 44.1kHz

Sony MZ-R37SP 4.625"

x 3.5" x

0.75"

160 g

(w/o

batt)

74min

stereo,

148min

mono

2 AA (15.5

hr play

time) or 2

NC-WMAA

NiMH (12

hr play

time)

20-20kHz 229.95 PCLink opt

(USB to

Optical

Digital Line

In); Line

Out to PC;

Both Real-

Time Only

Both ATRAC 44.1kHz

Sony MZ-B3 5.25" x

1.125"

3.125"

305 g

(w/o

batt)

74min

stereo,

148min

mono

3 AA (6 hr

play) or

LIP-12

LiIon

Recharge

(3 hr play

time)

20-20kHz 690.00 Line In,

Headphone

Jack Out

Only

Both ATRAC 44.1kHz

DAT

Sony NT2 4.375"

x 0.94"

x 2.5"

5.75 oz 60 or 120

min per tape 1 AA (5 hr

record time)

& 1 CR-

1220 Li

Button

>80dB,

Line In 10-

14.5kHz >80dB 1699.95 Line In/Out

Only Stereo NT

Format,

LDM-2

Modul

32kHz, 12

bit

nonlinear

(equiv to

17 bit)

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).

Maker Model Time/

Date

Stamp

Mic

Ext/Int Removable

Memory? Memory

Size (MB) Notes URL

Sony MZ-R70 No Ext Minidiscs 74/148 min Mini-disc

player/

recorder.

http://www.sony.com/

Sony MZ-

R37SP No Ext Minidiscs 74/148 min Mini-disc

player/

recorder.

http://www.sony.com/

Sony MZ-B3 Yes Both Minidiscs 74/148 min Mini-disc

player/

recorder.

VOR

capable.

Built-in Mic.

http://www.sony.com/

DAT

Sony NT2 Yes Ext Removable

Casette

Tape

60/120 min Micro-

cassette

player, tape

speed

6.35mm/sec

http://www.sony.com/

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

APPENDIX B

SOLID STATE RECORDER COMPONENTS

The following spreadsheet shows the major components used to make a flash based audio

recorder. The recorder features a dynamic range approaching 90dB, a bandwidth of 16kHz, and

has over 120 minutes of record time. The size of the recorder is dictated largely by the size of

the removable compact flash, and by the size of the batteries.

Table B-1. Solid State Recorder Spreadsheet

Target performance (per microcassette benchmark, but no AGC):

dynamic range (dB) 90 implies 16bits (but, may not get large dynamic ranges)

Bandwidth (kHz) 16 implies 32000samples/sec

record time (min) 120 implies3.686E+09bits of storage

460.8Mbytes of FLASH

compression ratio 2 implies 230.4Mbytes of FLASH

size (square inches surface area) 12.47 up tohalf VHS cassette

cost (dollars) $70 up to $500

Some initial guesses on size, power consumption needed to meet the modified microcassette benchmark

Component quan size (sq in)tot size current (mA) tot current cost ea tot cost

Microphone (remote, el cond) WM-61A 1 0.742 0.742 0.5 0.5 $ 1.52 $ 1.52

mic holder 1 0 0 $ 0.50 $ 0.50

mic cable (2 feet) 1 0 0 $ 0.41 $ 0.41

mic cable plug 0 0 $ -

mic cable jack 1 0.000 0 0 $ -

mic amp (AD8551ARM in RM8) 1 0.048 0.048 1 1 $ 1.89 $ 1.89

smt resistors (amp,anti alias filt) 3 0.012 0.037 0 0 $ 0.27 $ 0.81

smt caps (amp, anti alias filt) 3 0.008 0.024 0 0 $ 0.42 $ 1.27

24 bit delta sigma (store 16) CS5333 1 0.060 0.060 30 30 $ 4.43 $ 4.43

Prog Logic (XCR3032XL-10CS48C) 1 0.076 0.076 10 10 $ 2.30 $ 2.30

DSP (TMS320VC5502) 1 0.349 0.349 20 20 $ 10.00 $ 10.00

DSP Equiv 3.3V current for 1.5V 22.7 22.7 - -

start button 1 0.000 0 $ - $ -

CompactFlash256 1 7.165 7.165 21 21 $102.00 $ 102.00

Flash holder 1 0.000 $ - $ -

oscillator (ECS3953M-100-B) 1 0.058 0.058 0 $ 2.78 $ 2.78

DC/DC 3.3V (LTC1877EMS8) 1 0.023 0.023 0 $ 2.96 $ 2.96

DC/DC 1.5V (LTC1877EMS8) 1 0.023 0.023 0 $ 2.96 $ 2.96

battery holder 1 0.000 0 $ 0.70 $ 0.70

battery (AAA Alkaline) 3 0.656 1.969 1150mAh $ 0.70 $ 2.10

9.831 105.2273 $ 136.64

excldg mic

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

APPENDIX C

BODY WIRE PRODUCT SOURCE MATRIX

COMPANY

NAME STREET

ADDRESS PHONE FAX EMAIL

(M) Mfr

(D) Distrb

(N) NATIA PRODUCT

Accuquest

Corporation

P.O. Box 704

Hunt Valley,

21030

410-

584-

2355

410-

584-

2356 N

AMC Sales

193 Vacquero

Dr.

Boulder, CO

80303

303-

499-

5405

800-

926-

2488 D mini

microphone

Audio

Intelligence

Devices, Inc.

12301 NW 39th

St.

Coral Springs,

FL 33065

954-

255-

2619 donna.eagle@waida.com N narrow band

transmitters

Bugs &

Things UK

44-0-

116-

247060

44-0-

116-

24706

04 www.ukinternet-

marketing.co.uk/bugsnthings D mini

microphone

CCS

International

Counter Spy

Shop Rotterdam

31-10-

290-

9688 www.counterspyshop.com D pen transmitter

Datong

Electronics

Limited

Clayton Wood

Close, West

Park

Leeds, UK

LS166QE

44 113

2744

822 N

DTC

Communicati

ons, Inc.

Northeastern

Blvd.

Nashua, NH

3062

603-

880-

4411

603-

880-

6965

www.dtccom.com

http://www.epgctac.com/audi

o.htm N

audio

transmission

equipment

Global

Microwave

Systems

4141 Avenida

de la Plata

Oceaside, CA

92056

760-

631-

8021

760-

631-

8031 gms.gmsinc.com N

miniature

surveillance

equip.

Harris

Corporation

P. O. Box 37

Melbourne, FL

32902

407-

727-

6079 N

Innovative

Surveillance

Technology

11840 N.W.

41st Street

Coral Springs,

FL 33065

954-

755-

0724

954-

755-

0817 teamist@aol.com N

audio

surveillance

equip.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Intelligence

Support

Group, Lt. various

locations

760-

377-

5013

760-

377-

5073 from site onlu M surveillance

equip.

ISIS

Surveillance

Sytems and

Equipment

Co, Inc.

P.O. Box 577

Tyler, TX

75710

903-

533-

1712

903-

533-

1713 N

body worn

surveillance

systems

Law

Enforcement

Associates

100A Hunter

Place

Youngsville,

NC 27596

919-

554-

4700

919-

556-

6240 lea2@mindspring.com N

audio

surveillance

systems

M3 Media

Consultants,

Inc.

P. O. Box

510567

Punta Gorda,

FL 33951

941-

575-

7007

941-

575-

2727 m3papy@aol.com N

covert

surveillance

audio equip.

Premier

Wireless, Inc.

4749-C Bennett

Drive

Livemore, CA

94550

925-

449-

2101

925-

449-

9148 N body worn

transmitters

Probity

Electronics

Inc.

574 Meacham

Ave.

Elmont, NY

11003

516-

775-

3275

516-

355-

0225 probityelec@hotmail.com N,M,D body

transmitters

Schell

Electronics,

Inc.

120 N. Lincoln

Chanute, KS

66720

316-

431-

2350

316-

431-

2365 www.chanuteks.com/schell N,M,D surveillance

transmitters

Security

Research

Ltd.

Corby Road,

Weldon

Corby,

Northants, UK

NN173AR

153640

0988

15362

66711 marketing@security-

research.com N,M,D surveillance

equipment

Special

Electronic

Security

Products, Ltd.

Spectronic

Systems

3389 Sheridan

St., Suite 156

Hollywood, FL

33021

954-

359-

9847

954-

359-

9857 radome1494@aol.com NMD hardwire audio

systems

Spy City 1-888-

Spy-City D body

transmitters

Spy

Equipment

Store

877-

779-

0007

403-

237-

8130 D

body

transmitters

SpyZone

Swintek, Inc.

965 Shulman

Ave.

Santa Clara,

CA 95050

408-

727-

4889

408-

727-

3025 N,M

covert

transmitters

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Systems

Wireless, Ltd.

465 Herndon

Pkwy.

Herndon, VA

20170

703-

471-

7887

703-

437-

1107

Tactical

Technologies

, Inc.

1701 Second

Ave.

Folsom, PA

19033

610-

522-

0106

610-

522-

9430 rsnyder459@aol.com N,M body wires

Tektron Micro

Electronics,

Inc.

7483 B

Candlewood

Rd.

Hanover, MD

21076

410-

850-

4200

410-

850-

4209 tmei@erols.com N,M

digital stereo

audio

equipment

Teletron Ltd. 6 Halapid St.

Petack M mini transmitter

The Global

Spy Shops various

locations globalspy.com D

pen

microphone

The Spy

Shop from site only M mini

microphone

The Spy

Store

2627 West

Railway St.

Abbosford, BC

V2S2E6

604-

859-

4769

604-

859-

2799 D

pen

microphone

Audio Visual

Security Ltd.

64 Granville

Park, Blacrock

Co. Dublin

Ireland

353-0-

1287-

0055

353-0-

1287-

0056 alan@avsecurity.com M mini transmitter

Employers

Asset

Protection Raleigh, NC

888-

340-

5874

919-

250-

1998 www.eaprotection.com M micro-pen

Bull Electrical

250 Portland

Road

Hove Sussex,

UK BN35QT

44-0-

870-

740463

44-0-

1273-

32307

7 www.bullnet.co.uk D mini transmitter

Kubies

Electronics

P.O. Box 8681

Lexington, KY

40533

electronicsabc@mindspring.

com D mini mic

The Spy

Connection

5023 Camp

Bowie Blv.

Ft. Worth, TX

76107

877-

779-

2666 www.thespyconnection.com D mini mics (tie

clip)

Spygate

3811 Schaefer

Ave. Ste. I

Chino, CA

91710

909-

517-

1107

909-

517-

1105 sales@spygate.com M,D mini mic

E-Spyzone

(part of CCS

Int'l)

360 Madison

Ave. 6 FL

New York, NY

10017

212-

557-

3040

212-

983-

1316 information@e-spyzone.com D pen, mini mic

Lorraine

Electronics

Surveillance

716 Lea Bridge

Road

London, UK

E106AW

44-0-20-

8558-

4226

44-0-

20-

8558-

1338 salesinfo@lorraine.co.uk M pen mic, mini

trx

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Spy Supply

Online www.spysupplyonline.com D

mini

microphone,

pen

Spy Tech

Agency

8519-8521 W.

Sunset Blvd.

W Hollywood,

CA 90069

310-

657-

6333

310-

657-

8714 D

surveillance

mics

Cyber Gold

(Golden West

Investigative

Group, Ltd.)

41527-923,

12th Street

New

Westminster,

BC Canada

V3M1K0

604-

318-

8545

604-

521-

4085 www.cyber-gold.com D mini

microphone

Spymaster

972-8-

936-

2304 same

gmelnick@spymaster.co.il D body wire trx.

Advanced

Intelligence

Co. Ltd.

SpyMarketpla

USA Online

Services, Inc.

2500 Old

Alabama Rd.

Roswell, GA

30076

800-

490-

2723

770-

640-

6752 spy@spymarketplace.com D mini

microphone

Spy Surplus

800-

269-

0718

818-

475-

5330 www.spysurplus.com D body wires,

pen mic

Micro

Electrical

www.microelec.com M pen mic

Audiotel

International

Ltd.

Cavendish

Courtyard,

Sallow Road

Corby, England

NN175DZ

01536-

26-66-

01536

-26-

67-11

IBH-IMPEX

ELEKTRONI

K GMBH

Friederikenplat

z 55

Dessau

6844

0340-

240-02-

0340-

240-

02-44

ATET

Telematica

radiotelecom

unicazioni

V.G. da

Verrazzano 42

Torino, Italy

10129

39-011-

56-83-

200

39-

011-

59-04-

93 info@atet.it

Elvira

Production

Firm

Gidrogorodok,

Korpus A

Moscow

Region,

Zheleznotorozh

ny, Russia

143980

7-095-

522769

1 same firm_elvira@hotmail.com

JSC "Grant -

Systems &

Technologies

Parkovaya 9th

Str 53

Moscow,

Russia 105215 464-04-

81 same gstech@cityline.ru

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

PK Electronic

International

Security

Search Product

Sales - P.O.

Box 14237

Denver, CO

14237

303-

233-

7854

Twitco

Distributing

PO Box 239

Rindge, NH

03461

603-

899-

9800

603-

899-

9802

ewp@twitco.com

http://www.mv.com/ipusers/t

witco/ D

Earphones,

Microphones,

Covert

shrouds,

Headsets,

Tactical

Equipment

Covert-

Systems.com

By Ross

Associates

2495 Vista

Drive

Upland CA

91784

909-

981-

8855

909-

981-

7386

sales@covert-systems.com

http://www.ross.cc/index.htm

l D

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

APPENDIX D

SOLID STATE RECORDER AND BODY WIRE SURVEY RESULTS

The following tables contain the results of a survey submitted to a cross section of US law

enforcement agencies. The populations served by these agencies range from less than 1,000 to

over 1,000,000. The locations of these agencies are all across the continental United States. 77

responses were received from the survey. The survey asked a number of questions regarding the

typical use of recorders and body wires for law enforcement applications. The answers to these

questions are summarized in the tables below.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table D-1. Body Worn Recorder Survey Responses.

Our department uses body worn voice recorders on average ________ days a month.

Survey # Survey #

1 41 n/a

2 10 42 n/a

3 43 5

4 1 44 20

5 0 45

6 46 0

7 47 30

8 48

9 8 49

10 30 50

11 10 51 22

12 1 52 0

13 1 53 6

14 0 54 0

15 20 55 0

16 20 56

17 0 57 1

18 0 58 0

19 59

20 0 60 1

21 1 61 0

22 62 30

23 0 63

24 64

25 65 0

26 15 66 0

27 67 0

28 68 0

29 69 10

30 70 1

31 3 71

32 72 1

33 73 n/a

34 74 0

35 1 75 20

36 30 76

37 2 77 0

38 0.5

39 ?

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our department uses body worn voice recorders for the following types of operations.

Survey #

2 Officer buys (backup) Informant Buys (backup)

4 Crimes against person Drug Offenses arson Property Crime

9 Narcotics Robbery/Homicide Burglary Investigation Sexual Assault

10 Narcotics Prostittution Intelligence Gathering

11 Drugs

12 Drug Buys Alcohol Buys

13 Felonies Any Drug Cases

14 Drug Investigations

15 Narcotic Buys Prostitution

16 Undercover

18 Narcotics Personal Crimes

21 drugs Robbery/Homicide

24 interviews Traffic Stops

31 Drug Case Prostitution Cases

34 Drugs Intel Work

35 Narcotics Vice

36 Narcotics Gambling Prostitution

37 Narcotics Gambling Integrity White Collar

38 Major Crimes

39 Intelligence Demo

43 Narcotics

44 Traffic Stops Callout Response Impromptu Telephone Monitor

47 Officer Protection Interview/Investigation Investigate Officer Complaints Court Purposes

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

51 CI Drug Purchases U/C Drug Purchases Intelligence Gathering Assist CID

53 Undercover Drug Operations

54 n/a

55 0

57 Drug Investigations Stolen Property

60 Intelligence Gathering

62 Patrol Interviewing

65 Narcotics

67 n/a

69 Narc other

70 Narcotics guns Assaults

72 Drugs Burglary / theft Sexual Crimes Threat Complaints

75 Undercover Drug Investigations

77 n/a

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our department owns _______ body worn voice recorders.

Survey # Survey #

1 41

2 4 42

3 43 2

4 1 44 5

5 0 45

6 46 1

7 47 6

8 48

9 1 49

10 20 50

11 1 51 12

12 1 52 0

13 1 53 1

14 1 54 0

15 12 55

16 6 56

17 57 2

18 58 2

19 59

20 60 2

21 1 61

22 62 40

23 63

24 7 64

25 65 0

26 0 66

27 67 0

28 68

29 69 6

30 70 2

31 1 71

32 72 1

33 73

34 74

35 3 75 20

36 4 76

37 2 77 2

38 0

39 1

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

We require a minimum recording time of ___ minutes per use or ___ hours per operation.

Survey # Minutes Hours Survey # Minutes Hours

1 41

2 60 42

3 43 60 1

4 60 44 don't require

5 45

6 46

7 47 All contacts on assigned shift

8 48

9 90 2 49

10 2 50

11 60 1 51 90 3.5

12 60 60 52

13 53 90 8

14 54

15 90 55

16 n/a 56

17 57

18 58 2

19 59

20 60 90

21 90 61

22 62 60

23 63

24 n/a n/a 64

25 65

26 66

27 67

28 68

29 69 60

30 70 60

31 90 1.5 71

32 72 60 1

33 73

34 74

35 75

36 120 2 76

37 120 77 none set

39 1

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our Department stores the recordings for (days\weeks\months\years)

Survey # Days Weeks Months Years Survey # Days Weeks Months Years

1 41

2 5 42

3 43 x

4 forever 44 1

5 45

6 46

7 47 case by case basis

8 48

9 2 49

10 Trial/Appeals 50

11 As Long as Needed 51 5

12 x 52

13 x x 53 10

14 x 54

15 Till case is over 55

16 x 56

17 57 7

18 5 58 until case is tried

19 59

20 60 1

21 5 61

22 62

depends on situation

23 63

24 3 64

25 1 65

26 66

27 67

28 68

29 69 x

30 70

31 71

32 72 x

33 73

34 74

35 indefinite 75 x

36 76

37 77

38 90

39 1

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our Voice Recorders are (mini-casstte) (solid state) type

Survey # Mini Cassette Solid State Survey # Mini Cassette Solid State

1 41

2 x 42

3 43 x

4 x 44 x

5 45

6 46

14 x

28 68

47 x

8 48

9 49

10 x Digital 50

11 x 51 x I Wish

12 52

13 x 53 x

x 54

15 x 55

16 yes 56

17 57 x

18 58 x

19 59

20 60 x

21 x 61

22 62 x

23 x 63

24 x 64

25 x 65

29 69 x

30 70 x

31 x 71

32 72 x

33 73

34 x x 74

35 x x

36 x 76

37 77 x

39 x

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

We use Voice Recorders for:

Survey # Officer

Protection Intelligence

Gathering Testimony

Support Survey # Officer

Protection Intelligence

Gathering Testimony

Support

1 41

2 y y y 42

3 43 y y y

4 y y y 44 y y y

5 45

6 46

7 47 y y y

8 48

9 49

10 y y 50

11 y y y 51 n y y

12 y y 52

13 y y y 53 y y y

14 y y y 54

15 y y y 55

16 y y y 56

17 57

18 y y y 58 n y y

19 59

20 60 n y y

21 y y 61y

22 62 y y y

23 y y 63

24 y y y 64

25 y 65

26 66

27 67

28 68

29 69 y y

30 70 n y y

31 y y y 71

32 72 y y y

33 73

34 y y y 74

35 y y y 75 y y

36 y 76y y

37 n y y 77 y y

39 y y y

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our Voice Recorders are:

Survey # Dept Issued Personal

Purchase Dept Issued Survey # Personal

Purchase

1 41

2 x 42

3 43 x

4 x 44 x

5 45

6 46

7 47 x

8 48

9 x x 49

10 x 50

11 x 51 x

12 x 52

13 x 53 x

14 x 54

15 x 55

16 x 56

17 57 x

18 x 58 x

19 59

20 60 x

21 x 61

22 62 x x

23 x 63

24 x 64

25 x 65

26 66

27 67

28 68

29 69 x x

30 70 x

31 x 71

32 72

34 x

35 x 75 x

36 x 76

37 x 77 x

39 x

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Please rank the following items from 1-8 (1 most imprtant)

Survey # Size Record Time Battery Life Mike

Sensitivity Cost Voice

Operated Operating

Controls

5 7 4 2 8 6

4 7 8 1 2 5 3 6

8 2 6

3 4 2 1 7 6

14 1 2 3 8 4 5 7 6

21 2 1 3 6 5 4 8 7

34 5 4 6 8

3 2

43 8 8 1 8

Packaging

2 1 3

4 4 3 7 1 2 8 5 6

9 2 4 5 1 2 6 5

10 1 3 5 2 4 7 8 6

12 1 3 5 7 4

13 5 8

15 1 2 3 8 8 6 4

16 1 3 6 2 4 8 5 7

23 2 3 1

24 3 6 7 8 5 1 5 4

25 1 2 8 7 3 5 6 4

31 1 6 4 3 2 7 8 5

1 3 2 7

35 1 5 6 4 8 7

36 4 3 2 5 7 6 8 7

37 1 2 6 4 5 3 7 8

39 1 7 6 4 2 5 3 8

8 8 8 8

44 6 8 5 7 4 3 2 1

47 6 5 3 7 2 4 8 1

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

51 4 5 1 3 2 8 7 6

52 1 3 2 4 5 7 8 6

53 1 2 3 4 5 7 8 6

57 1 5 7 3 2 4 8 6

58 3 1 2 4 7 5 8 6

60 2

6 3 4 5

75 3 1 5

3 6 5 1 8 4 7

62 1 7 2 8

69 4 1 3 5 2 7 8 6

70 4 7 6 3 1 8 5 2

72 1 2 2 1 1 2 2

2 4 7 6 8

77 3 5 8 1 2 7 6 4

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

The courts in our area (allow) (don't allow) voice recording of ofcr interviews as evidence.

Survey # Allow Don't Allow Survey # Allow Don't Allow

20 60

1 41

2 x 42

3 43 x

4 x 44 x

5 45

6 46

7 47 x

9 49

10 x 50

11 x 51 x

12 x 52 x

13 x 53 x

14 54

15 x 55

16 56

57 x

18 x 58 x

19 59

21 x 61

22 x

23 x 63

24 64

25 x 65

26 66

27 67

28 68

29 69 x

30 70 x

31 x 71

32 72 x

33 73

34 x 74

35 x 75 x

36 x 76

37 x 77 x

39 x

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

What improvement would you like to see in your current voice recorders?

Survey #

ability to record without mic having to be at neck level

cost

2 Mike sensitivity - quality & operating controls

9 Concealment

10 Digital recorders offer best convenience, size, and clarity

13 More recording time and better mic sensitivity,

16 Size, Voice operated mike sensitivity

I prefer concealed wire of greater ouput power and increased range to use of "pager" style wires. Although

the pager/wire/xmtrs are great for officer saftey vis-a -vis discovery, they really provide a poor/fluctuating

signal-which can also compromise saftey and limits evidencing value.

21 Voice quality - voice freq improvement

24 lower cost for better units

25 Ability to reduce or eliminate motor noise in recording/playback

36 Smaller, better mic

43 Smaller, more concealable

44 Clarity, Reliability (sturdiness)

47 ease of one touch controls, recording quality & time. Size of unit.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

51 Be Digital

53 Longer recording time. Better Recordings. Digital Recorders.

58 I would like the recorders to be easier to conceal

60 n/a

72 easy concealment, clarity

75 Size

77 would like to see full range of products & how they can be used in the field.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

COMMENTS

Survey #

1 The body wire/repeater/recorder that we currently use is ver user friendly. Has many features and the recordigs are

clear and easily understood.

3 We can no longer use the traditioinal wire transmitters because of RF Detectors and scanner technology. We now use

digital recorders. It would be useful to have an emergency transmitter only.

8 Currently our department does not own or use a body worn transmitter or recorder. However we are interested in

obtaining additional information for possibly future purchases.

Dream: To have equipment that always works.

My department has two bike patrol officers. I would be interested in info on the new technology you have available.

Durability is a primary concern along with comfort and sensitivity. A follow up from your company would be

appreciated. B.H.

Question #1 Reflects use of concealed narcotics use. Question #3 7 of 10 units are used in video/audio in patrol

units. 3 units are for undercover use.

We use the mics from our mobile vision camera system everyday for everything. Officers keep a recorder record of

every contact with public. (We go through 1 video tape per officer per day) Peole do not know a record is being kept.

It works well for all purposes.

39 Thank you for the opportunity to complete this survey.

40 Our department only uses body wires on rare occassions and all operations and equipment are conducted and

maintained by the Bucks Co. District Attorneys Office County Detective Bureau.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

48 We do not own body worn recorders. Thank you for your concern with our needs. Sgt Martin.

We are in the process of converting to all digital equipment. There is not enough digital body wire/ recorder reciever

equipment to choose from. Further we are looking for a reliable, clear, comparable range to body wire, body worn

video transmitters.

52 We currently do not use body worn recorders, but is an option that is being looked into.

We are not allowed to use body wires in the state of Oregon as this time.

We have used in car video camera mikes on several occasions. Sound seems to be very clear and units are

dependable. I have had problems with our wires cutting in and out on numerous occasions. Seems like when the

antenna gets a kink or twist in it, cuts out sound. Range is very poor.

Hopefully I did not misunderstand the questionnaire. We use body worn transmitters daily in patrol section. Covert

usage involves borrowing equipment. We do not own and use infrequently. Most officers rely on body transmitters;

few use personal micro-cassette recorders in addition. Please call if you need further.

71 Our department primarily uses covert communications devices for steak-outs conducted in the field. These devices

are compatible with our current "hand held" Motorola Saber radios.

We are currently looking to purchase new equipment since ours is outdated. I am now looking to compare different

styles and prices. I would greatly appreciate any assistance you can offer. I don't know if you have info on this or any

grants that would help purchase better equipment. Thanks in advance.

76 The Greenwich PD used to have operable video cameras and body wires in two patrol cars. The equipment became

obsolete and out-dated and is no longer used. Although, in the future we would like to acquire new cameras.

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Table D-2. Body Worn Transmitter Survey Responses.

Average use of body wires per month.

Survey # Survey #

1 8 41 72

21 1 61 0

22 1 62 20

23 16 2

Very Often

2 30 42 20

3 0 43 25

4 1 44 2

5 6 45 0

6 1 46 10

7 0 47 n/a

8 0 48 10

9 8 49

10 50 1

11 10 51 32

12 1 52 5

13 1 53

14 15 54 0

15 20 55

16 20 56 8

17 8 57 1

18 58 30

19 8 59 3

20 2 60 12

24 0 64 0

25 20 65 10

26 10 66 3

27 31 67 2

28 68 1 Undercover use everyday

29 69 30

30 1 70 30

31 15 71

32 14 72 2

33 73 1

34 74 2

35 6 50

36 30 76 n/a

37 8 77 2

38 5

39 ?

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our department uses body worn voice recorders for the following types of operations.

Survey #

1 Illegal Narcotics Delivery Stings Gather Info

2 Officer Buys Officer Buy/Bust

Alcohol

Alcohol Compliance

24 n/a

Domestic Abuse

30 Narcotics Purchase

Narcotics

Major Crimes

Narcotics

Stings

Drug Invest

Sexual Abuse Minor Burglary/Theft

Informant buys Informant buy/bust

3 Narcotics Crimes Serious Felonies

4 Crimes against Persons Drug Offenses Arson Property Crimes

5 Narcotics Stolen Property

8 n/a

9 Narcotics Burglary Investigations Homicide Invest Sexual Assault Invest

10 Narcotics Prostitution Money Laundering Informants in other crimes

11 Drug Alcohol Stings

12 Drugs

13 Felonies Drug Cases

14 Drug Investigations Prostitution

15 Narcotics Buys Prostitution

16 Undercover

17 Drug investigations

18 Narcotics Personal Crimes Prostitution Property Crimes

19 Narcotics Major Crimes

20 Narcotics

21 Drug Robbery

22 Drug Other Criminal

23 Bike Patrol Tavern Walk Thru Narcotics Surveillance

25 Drunk Driving Stops

26 Narcotics Patrol/Criminal Patrol Invest Interviews

27 General Patrol Assault Crime Invest

Officer Protection

31 Drug Cases Prostitution

32 Burglary/Stolen Property Sex Crimes

34 Drugs Intel work

35 Vice

36 Narcotics Prostitution Gambling

37 Narcotics Gambling

38 Robberies Burglary

39 Survey Demo Intellig gathering

42 Narcotics Informants

43 Narcotics

44 Sex Crimes Inmate Contacts Property Crimes

46 Undercover Narcotics Prostitution Vice

48 Drug Operations Sexual Assault

50 Drug

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

51 CI Drug Purchase Homicide Invest

Gathering Information

Narcotics Other

Drugs Theft Sexual Crime Threat Complaints

Narcotics Vice

U/C Buys

Vice

U/C Drug Purchaces CID Investigation

52 Drugs Burglary Vice

53 Drugs Stolen Property

54 n/a

55 Traffic Stop DWI/DUI Enforcement Domestics

56 Narcotics

57 Drug Investigations Stolen Property

58 Drug Investigations Buying illegal weapons Murder Investigations

59 Narcotics Thefts Burglaries Forgeries

60 Undercover Drug Buys Informant Drug Buys Prostitution Stings

62 Drug Investigations Sexual Abuse of Minors Sexual Assault

63 Drug Property Crimes

65 Narcotics Invest

66 Drug Buys Hotel Room Surveillance Prostitution Invest

67 Drug Investigations

68 Narcotics Patrol

70 UC Drug Purchase UC Gun Purchases Officer Safety

74 CI Buys Officer Safety

75 Drug Investigation Criminal Invest

76 N/a

77 Narcotics Fraud

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our department owns _______ body wires.

Survey # Survey #

28 50 0

11 1

1 53 1

14 4 54 0

15 8

31 3

32 2 72 1

2 41 12

2 42 9

3 1 43 2

1 44 2

5 1

6 1 46 3

8 0 48 1

9 3 49

51 6

12 1 52 11

55 2

16 8 56 3

17 3 57

18 58 3

19 2 59 2

20 2 60

21 2 61

22 0 62 1

23 63 2

24 0 64 0

25 2 65

26 10 66 3

27 2 67 2

28 68 5

29 69 12

30 2 70

73 0

2 74 2

35 4 75 5

36 4 76 0

37 3 77 1

38 0

39 ?

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

On occasion we borrow body wires Y/N.

Survey # Other Local

Department State Agency Federal

Agency Survey #

Other Local

Department Federal

Agency

n n

n n n n n

15 n

n 63 y y

State Agency

1 y 41 n n n

2 n n n 42 n n n

3 n n y 43 n

4 y 44 y y n

5 y y n 45

6 y n n 46 y n n

7 47

8 n n n 48 n y n

9 n y y 49

10 n n y 50 y

11 y y 51 n n n

12 n n n n n n

13 y y 53 n

14 n 54

n n 55 y y y

16 n n n 56 n n n

17 n n n 57 y

18 n n n 58 n n n

19 y y y 59 n n n

20 n n n 60 n n n

21 n n n 61

22 y 62 n y

23 n n y

24 n n n 64 n n n

25 n n n 65 n y y

26 y y 66 n n n

27 67 n n n

28 68 y y n

29 n n n 69 n n n

30 n y y 70 n n n

31 y 71

32 n n n 72 n n n

33 73 y y

34 y 74 n y y

35 n n n 75 n n n

36 y y y 76 n n n

37 y y n 77 n y n

38 y

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

We obtain our equipment:

Survey

# Dept

Purchase

State

Agency

Purchase Procurement

Cooperative

Loan from

State/Fed

Agency Other Dept

Purchase Procurement

Cooperative Other

Survey

State

Agency

Purchase

Loan from

State/Fed

Agency

1 x 41 x

2 x 42 x

3 x HIDTA 43 x

4 x 44 x

5 x 45

6 x 46 x

7 47

8 x 48 x

9 x x x x 49

10 x x 50 x

11 x x 51 x x

12 x 52 GRANTS

13 x 53 x

14 x 54 x

15 x x 55 x

16 x 56 x

17 x 57 x

18 x 58 x

19 x 59

x x

20 x 60 x

21 x x 61

22 x 62 x

23 x 63 x

24 x 64

25 x 65 x GRANTS

26 x 66 x

27 x x 67

28 68 x x x

29 69 x

30 x 70 x

31 x 71

32 x 72 x x

33 73 x

34 x 74 x

35 x x 75 x

36 x 76

37 x 77 x x

39 x

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our Department uses body wires that operate (y/n)

Survey # VHF UHF GHZ Spread

Spectrum Survey # VHF UHF GHZ Spread

Spectrum

1 y 41 y n n n

2 y n n n 42 y n n n

3 y 43

4 y n n 44 y

5 y n n n 45

6 y n n n 46 y y n n

7 47

8 y 48 n n n

9 y y 49

10 y y y n 50

11 y 51 y n n n

12 52 y n n n

13 n y n n 53 y

14 54

15 y n n n 55 y

16 56 y n n n

17 y n n n 57 y

18 y y n n 58 y

19 y 59 y n n n

20 y 60 n y n n

21 y 61

22 62 y n n n

23 y n n n 63 y

24 64

25 y 65

26 66 y n n n

27 y n n n 67 y n n n

28 68 n y n n

29 69 y n y n

30 70 y n n n

31 n n n n 71

32 y 72 y n n n

33 73 y

34 y 74

35 y n n n 75 n y n n

36 n n 76 y n

37 y n n n 77

38 y

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Our Department owns body wires manufactured by the following companies:

Survey # Survey #

1 Tactical Technologies AID 41

2 AID LEA 42 Motorola, LEA, AID

3 Unkown 43 AID

4 AID / Westinghouse 44

5 AID 45

6 AID / Westinghouse 46

7 47

8 n/a 48 AID & Westinghouse

9 AID LEA 49

10 AID 50

11 Law Enforcement Associates 51 AID & TTI

12 52 AID

13 53 AID

14 AID, LEA 54 N/A

15 55 TELEX

16 AID 56

17 AID 57

18 Unkown 58 TTI

19 LEA, AID 59 LEA

20 AID 60 AID TELEX

21 Tactical Technologies 61

22 n/a 62 TTI

23 Parmarlow 63 AID

24 n/a 64

25 65 Dynatech

26 TEA 66 LEA

27 Mobile Vision 67 TTI, LEA

28 68 Mobile Vision

29 69 AID, LEA

30 70 DTC

31 AID 71

32 AID 72 LEA

33 73

34 74

35 TTI and AID 75 AID

36 ProTech 76

37 AID and TTI 77

38 Unkown

39 ?

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

When our body wires need repair we:

Other

x 49

13 x

16 x

58 x

19 x 59 x

31 x 71

33 73 x

34 x 74

Survey # In-House

Repair Return to

Manufacturer Send to Local

Radio Shop Other Survey

# In-House

Repair Return to

Manufacturer Send to Local

Radio Shop

1 x 41 x

2 42 x x

3 x 43 x

4 x 44 x

5 x 45

6 x 46

7 47

8 48

x 50

11 x 51 x x

12 52 x

x 53

14 x N/A

15 55 DEALER

x 56

17 x 57 x

18 x x

20 60 x

21 x 61

22 x 62 x x

23 x 63 x

24 N/A 64 x

25 x 65 x

26 x x 66 x

27 x 67 x

28 68 x x

29 69 x x

30 x x

32 x 72 x

35 x 75 x

x 76

37 x x x

38 x

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Please Rank the following items from 1-10 (1 most important)

Survey # Size Range Battery Life Tx Freq Mike

Sensitivity Built in

Recorder Cost Encryption

Audio

Adjustment

1 8 2 5 3 1 6 10 7 4 9

10 5 8 8 3

10 1 3 5 9 4 6 10 8 7 2

5 1 7 6

1 5

16 1 4 9 8 10 7 3

1 3

1 2 6 9 4

5 10 3 9 7

Packaging

2 5 1 3 10 2 7 6 9 8 4

3 3 4 3 2 8 4 1 6 2

4 3 5 6 10 1 7 9 8 2

5 2 4 7 5 3 10 6 8 1

6 2 1 4 3

9 2 4 5 7 6

11 3 9 4 10 8 2

12 4 6 10 2 8 3 9 7 1

13 4 2 6 9 1 7 8 5 3

14 1 2 5 4 6 8 3 7 9 10

15 2 4 7 6 9 3 8 10

2 5 6

1 3 4 10 6 8 5 7 9 2

18 1 4 7 5 3 6 2 9 8 10

19 6 2 3 8 1 10 7 5 9 4

20 2 1 4 8 3 10 7 9 6 5

21 3 1 2 6 4 7 5 9 10 8

22 1 2 10 6 3 8 5 7 9 4

23 3 1 6 2

25 4 5 2 9 6 7 1 8 3 10

26 2 3 9 6 8 1 10 4 5

27 2 4 5

30 1 2 8 10 4 9 3 7 6 5

31 2 1 6 7 5 8 3 9 10 4

32 4 1 5 7 2 9 6 8 10 3

34 1 2 6 10 3 8 4 9 7

35 5 7 10 8 3

36 2 1 5 6 4 9 5 7 8 3

37 1 2 4 7 6 9 5 10 8 3

39 1 3 9 6 2 4 5 7 8 10

41 2 5 4 7 3 8 6 9 10 1

42 3 2 4 6 5 9 8 7 10 1

43 8 8 5 8 8 1 8 1 5 8

44 5 2 6 8 3 7 4 9 10 1

46 7 2 4 1 3 10 9 6 5 8

48 1 2 8 6 4

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

50 6 2 8 3 5 1 4 9 7

51 2 1 7 10 8 6 5

3 6 8

3 2

5 2

3 7

4 3 9

2 3 5 9 6 7 8 4 10 1

53 1 2 4 7 3 8 10 5 9 6

55 4 2 6 5 1 10 3 7 8 9

56 7 1 2 10 4 8 6 5 9 3

57 1 4 7 6 2 10 3 8 9 5

58 3 1 4 10 7 2 6 9 8 5

59 4 1 5 7 6 3 10 9 2

60 3 4 5 6 1 9 8 10 7 2

62 3 8 10 4 6 5 7 9 2

63 1 4 3 8 6 10 7 5 9 2

64 1 2 3 6 4 8 5 10 7 9

65 2 4 6 8 5 9 7 10 3

66 3 1 6 10 2 8 4 7 9 5

67 3 2 4 6 5 9 7 10 8 1

68 5 1 10 2 7 9 4

69 1 5 4 9 7 6 10 8

70 6 1 2 5 4 8 10 9 7

72 1 1 3 1 7 2 1 1

73 1 2 6 10 4 8 5 9

74 4 2 3 7 10 5 9 8 1

75 1 2 6 4 7 9 8 5 10 3

77 4 3 8 10 2 6 5 9 7

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

We Use Body Wires For:

Survey # Intelligence

Gathering Survey # Intelligence

Gathering

y y n

y y

Officer

Protection Officer

Testimony Officer

Protection Officer

Testimony

1 y y y 41 y y y

2 y y y

3 43 n y y

4 y y 44 n y y

5 y y 45

6 y y 46 y y y

7 47

8 48 y y y

9 y y y 49

10 y y y 50

11 y y y 51 y y y

12 y 52 y y y

13 y 53 y y

14 y y 54

15 y y 55 y y y

16 y y y 56 y y n

17 y n y 57 y y y

18 y y n y y y

19 y y y 59

20 y y y 60 y n y

21 y y y 61

22 y y y 62 y y

23 y y n 63 y y y

24 64

25 65 y y y

26 y y y 66 y y y

27 y y 67 y y

28 68 y y y

29 69 y y y

30 y y 70 n n

31 y y y 71

32 y y 72 y y y

33 73 y

34 y y y 74 y y y

y y y 75 y y y

36 y y y 76

37 y y y 77 n y y

38 y y y

39 y y y

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

What improvement would you like to see in your current equipment?

Survey #

1 I'm very pleased with TTI's body Wire

2 Range & Quality of Recording

5 Noise Filtering

6 None

38 size

smaller, more concealable body wires

9 Clarity

10 Further, Stronger Transmissions

11 Reliability of signal to cover units

12 Size

13 First to obtain additional equipment. To get more range on our transmitter

14 Better Range and clarity

15 Smaller, greater range.

17 Lower cost

18 Smaller, more audible

19 Greater Range and battery life

20 Would like to go digital with repeater system

21 Simpler Operation

22 We are satisfied

Overall I'm pleased with my radio and earpiece. I would like to upgrade to hands free, voice activated comm.

Officer Safety issue - keep my hands free.

24 n/a

26 Size (power source) heavier duty cords (to keep size to a minimum maybe shield w/kevlar for strength) to

prevent internal wire breakage to a minimum

27 more durability

30 better clarity with signal

31 Consistent range without a repeater

32 Sturdier connection between antenna and plug/connector as well as mic and plug/connector

36 Range of Transmitter

37 Overall transmitted voice quality and separation from background noise

39 size

41 Purchased new wires within 2 months

42 1 watt in small size and 800 MHz body wire

44 audio clarity

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

48 Encryption on all available transmitters.

51 To be not detectable by counter-measures (RF-detector/counter, etc) Also be digital.

52 Updated

53 Change to cellular transmission or synthesized systems

55 More Units

58 I would like it to be smaller and to have a built in digital recorder

60 n/a

62 increased transmitter wattage for increased range

65 Durability

66 Longer Range, mike sensitivity, battery life

67 Increased mike sensitivity, more concealable repeater

68 Range and Durability

70 Lighter in weight

72 Make it smaller, easier to conceal, clarity

73 Frequencies on devices that can't be detected.

74 Updated concealment covers, better range, more power, smaller size.

75 Sound quality and range/concealment/we need video, video, video !!!

77 Better Concealability

This document is a research report submitted to the U.S. Department of Justice. This report has not

been published by the Department. Opinions or points of view expressed are those of the author(s)

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.

Personal Electronics For Law Enforcement Solid State Recorders And Body Wires Olympus Microcassette Recorder DW 90 210488

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