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 Federallyfunded 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.

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

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

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

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.

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
2

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

300-3kHz
LP
300-5kHz

$175
with
32MB

$50 64MB
$15 16MB
Smartmedia

2hrsSP16MB

SP
DSS format

MP3
3.7”x2.6”x0.9”
(Creative Labs
Nomad IIc)

133min 32MB
66min 16MB

G721
ADPCM
format

$114
with
64MB

$30 32MB
$15 16MB
Smartmedia
card

Minidisc
(Sony
MZ-N707)

5 hrs 1 MD

ATRAC3
format

$230

$2.50 minidisc

Digital Audio 1.125”x3.125”x
Tape
(Sony 4.625”
TCD-D100)

120 min
90 min
60 min

20-22kHz

$750

$5.50 120min
$4.50 90min
$4.00 60min

Microcassette
(Sony M850V)

120 min
90 min

250-4000Hz

$65

$2.50 120min
$1.50 90min

3.25”x3”x1.3”

4”x2.25”x0.88”

60 min

card

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

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 nonremovable 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
4

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 (ICDB25) 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
5

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
6

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 prerecorded 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,
7

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
8

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

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

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

3.1

CURRENT AND PROJECTED STATE OF THE ART IN SOLID STATE
RECORDER TECHNOLOGY AREAS

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
11

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.

OPERATOR
INTERFACE

MICROPHONE

AMPLIFIER/
FILTER

ENCODER (ADC)

COMPRESSION
(DSP or ASIC)

REMOVABLE
STORAGE
(FLASH)

POWER SUPPLY
(BATTERIES)

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.

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.

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
14

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
15

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”
16

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)
17

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.
18

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.

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.nectokin.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
20

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.

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
22

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.

$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.

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.

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

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.

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

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.
28

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.
2.
3.
4.
5.
6.

Voice Quality of the Received Audio
Transmission Range
Battery Lifetime
Physical Disguise
Electronic Security
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.

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

Quiet Whisper at 5 feet

Quiet Office

Average Conversational Speech

Shout

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

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.

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

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.

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

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.
35

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

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.

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.

MICROPHONE

BATTERIES

AMPLIFIER/
FILTER

VOLTAGE
REGULATOR(S)

ANTENNA

ANALOG TO
DIGITAL
CONVERTER

FREQUENCY
SYNTHESIZER

MATCHING
NETWORK

ERROR CODING,
DIFFERENTIAL
ENCODING

BPSK
MODULATOR

POWER AMP

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

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.

MICROPHONE

BATTERIES

AMPLIFIER/
FILTER

VOLTAGE
REGULATOR(S)

ANTENNA

ANALOG TO
DIGITAL
CONVERTER

PN SEQUENCE
GENERATOR

FREQUENCY
SYNTHESIZER

MATCHING
NETWORK

ERROR CODING,
DIFFERENTIAL
ENCODING

XOR

BPSK
MODULATOR

POWER AMP

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.

BATTERIES

ANTENNA

MICROPHONE

VOLTAGE
REGULATOR(S)

MATCHING
NETWORK

AMPLIFIER/
FILTER

FREQUENCY
SYNTHESIZER

POWER AMP

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

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.

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

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 changeover 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.

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

Record
Time

Power
Needs

Memorex

MB002

2.17" x
3.58" x
0.59"

3.8 oz

16 min

Memorex

MB005

2.38" x
4.25" x
0.85"

4 oz

Netvox

V901

85mm x
60mm x
52mm

Netvox

V901P

85mm x
60mm x
52mm

Olympus

DS150

Olympus

D1000

Olympus

V90

Olympus

Nom.
Bandwidth
SNR (dB)

Dynamic
Range

Cost

PC
Interface

Stereo/
Mono

Voice
Sample
Encoding Freq / Bit
Rate

2 AAA, 5
hr record

39.99

Mono

32 min

2 AAA, 5
hr record

49.99

Mono

70 g w/
batt

15 min

2 AAA
(3V), 75
mA record

Mono

4.8kbps
compress

70 g w/
batt

60 min

2 AAA
(3V), 75
mA record

Mono

4.8kbps
compress

4.6" x 1.6" 2.9 oz w/o
LP:160 2 AAA, 10 Line-in:44
Built-in
x 0.6"
batt
min SP:75 hr record
Mic: 38
min (8MB
Int)

LP:300Hz3kHz
SP:300Hz5kHz

179.00

Serial/
USB

Mono

SP:12kHz,
DSS
13.7kbps
(Digital
LP:8kHz,
Speech
Standard) 6.3kbps

5.5 oz w/o LP:34 min 2 AA, 8 hr Line-in:44
Built-in
batt
SP:16 min record +
w/ 2MB CR1220 Li Mic: 38
button
card;
LP:72 min
SP:33 min
w/ 4MB
card

LP:200Hz2kHz
SP:200Hz5kHz

214.00

Laptop/
PC
Adapter
Card
(PCMCIA)

Mono

SP:12kHz
SCVA
LP:8kHz
(Silent
Compress
Voice
Activ)

4.7" x
1.81" x
0.91"

4.5" x 1.5" 1.6 oz w/o LP:90 min 1 AAA, 10
x 0.5"
batt
SP:33 min hr record

Built-in
mic: 41

LP:300Hz1.7kHz
SP:300Hz3.5kHz

108.00

No,
Headphon
e Jack
Only

Mono

VN90

4.6" x 1.6"
x 0.6"

2.3 oz

LP:90 min 2 AAA, 17
SP:33 min hr record

Built-in
mic: 41

LP:3001.7kHz
SP:3003.5kHz

93.00

No,
Headphon
e Jack
Only

Mono

Olympus

VN180

4.6" x 1.6"
x 0.6"

2.3 oz

2 AAA, 17
LP:180
min SP:66 hr record
min

Built-in
mic: 41

LP:300Hz1.7kHz
SP:300Hz3.5kHz

119.00

No,
Headphon
e Jack
Only

Mono

Panasonic

RRQR240

2.2" x 3.5"
x 0.5"

2 oz

37 (Built-in HQ:450Hz2 AAA
LP:240min
5.0kHz
SP:120 (3V), 30 hr Mic, HQ
mode)
record
min HQ:60
min

146.00

No,
Earphone
Out Only

Mono

Panasonic RR-QR80 2.2" x 3.5"
x 0.5"

2 oz

37 (Built-in HQ:450Hz2 AAA
LP:60min
5.0kHz
SP:30 min (3V), 30 hr Mic, HQ
mode)
record
HQ:15 min

92.00

No,
Headphon
e Jack
Only

Mono

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns).
URL

Mic
Ext/Int

Removable
Memory?

MB002

Int

Built in Flash

Memorex

MB005

Int

Built in Flash

Netvox

V901

Int

Built in Flash

http://www.netvox.com.tw/english/vrecorder.htm

Netvox

V901P

Int

Built in Flash

http://www.netvox.com.tw/english/vrecorder.htm

Olympus

DS150

Yes

Both

Built in Flash

Olympus

D1000

Intel
Removable
Flash Memory
Cards: 2, 4,
8MB available

Olympus

V90

Model

Memorex

Int

Memory
Size
(MB)

Notes

Time/
Date
Stamp
No

Maker

VOR capable

http://store.yahoo.com/igadget/digvoicrec1.html

Built in IC

Olympus

VN90

Both

Built in IC

Olympus

VN180

Both

Built in IC

Panasonic

RRQR240
RRQR80

Yes

Both

Built in Flash

Yes

Both

Built in Flash

Panasonic

http://store.yahoo.com/igadget/digvoicrec1.html

VOR capable. Hi/Lo
Mic. Pkg w/ ViaVoice
software for $220.
8MB cards available
(SP:72 min
LP:148min). VOR
Capable. Pkg w/
ViaVoice software for
$289.99. Opt Flash
Card Reader/ Writer
for PC.
VOR Capable. Hi/Lo
Mic
VOR Capable. Hi/Lo
Mic
VOR Capable. Hi/Lo
Mic
VOR Capable. Hi/Lo
Mic
Same as RR-QR240
but less memory

http://www.zap1.com/comparisons.html

http://www.zap1.com/comparisons.html
http://www.zap1.com/comparisons.html
http://www.zap1.com/comparisons.html
http://www.prodcat.panasonic.com/shop/product.asp?sku=RRQR240&CategoryID=225
http://www.prodcat.panasonic.com/shop/product.asp?sku=RRQR80&CategoryID=225

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).
Maker

Model

Size

Samsung Voice Pen 6" x 0.65"
SVR-P220
diam

2 oz

Samsung Voice Pen 5.8" x 0.7"
SVR-P700
diam

2 oz

Record
Time

Power
Needs

LP:138min 1 AAA, 8
SP:70min hr record

70 min

1 AAA, 4
hr record

Nom.
Bandwidth
SNR (dB)

Dynamic
Range

Cost

PC
Interface

Stereo/
Mono

Voice
Sample
Encoding Freq / Bit
Rate

Built-in
mic: 40

500Hz3.5kHz

229.00

Line Out
Jack

Mono

ADPCM

Built-in
mic: 40

100Hz-4kHz

185.00

Line Out
Jack

Mono

ADPCM

Samsung

102mm x
Voice
Stick SVR- 36mm x
17mm
S820

64 g w/
batt

LP:502min 2 AAA, 10
SP:233mi hr record
n

500Hz3.5kHz

225.00

Line Out
Jack

Mono

Samsung

4.75" x 1"
Voice
x 0.5"
Stick SVRB410

1.5 oz

LP:250min 2 AAA, 8
SP:115mi hr record
n

500Hz3.5kHz

160.00

Line Out
Jack

Mono

Samsung

3.5" x 2.1"
Digital
x 0.9"
Recorder
SVR-N200

2 oz

LP:119min 2 AAA, 10
SP:59min hr record

500Hz3.5kHz

99.00

Line Out
Jack

Mono

Sony

ICD-R100 0.5" x 4" x
1.75"

68g w/
batt

LP:150min
2 AAA
SP:64min (3V), 19 hr
record

SP:280Hz4.8kHz
LP:240Hz3.2kHz

169.95

Parallel

Mono

ICS (Sony SP:11kHz
ADPCM)
LP:7kHz

68g w/
batt

LP:150min
2 AAA
SP:64min (3V):19 hr
record

SP:280Hz4.8kHz
LP:240Hz3.2kHz

199.95

Parallel

Mono

ICS (Sony SP:11kHz
ADPCM)
LP:7kHz

2 AAA
(3V)

179.95

Parallel

Mono

ICS (Sony
ADPCM)

79.99

Mono

ICS (Sony
ADPCM)

SP:8kHz

99.95

Mono

MSV or
ICS (Sony
ADPCM)

6.5kHz

99.99

Mono

ICS (Sony
ADPCM)

SP:8kHz

Sony

ICDR100PC

0.5" x 4" x
1.75"

Sony

ICD-70PC

0.938" x
3.375" x
2.375"

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

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

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

1.8 oz w/o LP:24min
batt
SP:16min

280Hz2.8kHz

SP:9.5kbp
s
LP:4.7kbp
s

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).
Time/
Date
Stamp
No

Mic
Ext/Int

Removable
Memory?

Int

Built in
Flash

Voice
Pen
SVRP700

Int

Built in
Flash

Samsung

Voice
Stick
SVRS820

Both

Built in
Flash

Samsung

Voice
Stick
SVRB410

Both

Built in
Flash

Samsung

Digital
Recorder
SVRN200
ICDR100

Both

Built in
Flash

Yes

Both

Built in IC
Flash

Maker

Model

Samsung

Voice
Pen
SVRP220

Samsung

Sony

Memory
Size
(MB)
16

Sony

ICDR100PC

Yes

Both

Built in IC
Flash

Sony

ICD70PC

Yes

Both

Built in IC
Flash

Sony

ICD-35

Sony

ICD-37

Yes

Built in IC
Flash
Built in IC
Flash

Sony

ICD-55

Built in IC
Flash

Int

Notes

10 levels
of volume
control
(digital).
Output to
PC not
usable for
speechto-text
programs.
10 levels
of volume
control
(digital).
Output to
PC not
usable for
speechto-text
programs.
10 levels
of volume
control
(digital).
VOR
Capable
10 levels
of volume
control
(digital).
VOR
Capable

URL

http://www.zap1.com/comparisons.html

VOR
capable,
Hi/Lo Mic,
same as
ICD-R100
PC but
w/o PC
Interface
pkg
VOR
Capable,
Hi/Lo Mic,
Hold
Switch
VOR
Capable,
Hi/Lo Mic,
Min
Record
Segment
4 sec,
Hold
Switch

http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html
Hi/Lo Mic,
Hold
Switch

http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).
Maker

Model

Size

Record
Time

Power
Needs

Sony

ICD-67

2.125" x
3.375" x
0.875"

2.75 oz
w/o batt

180 min

1 AAA, 5
hr record

Sony

ICD-V21

2.125" x
3.375" x
0.875"

2.75oz

10 min
Max

1 AAA, 6
hr record

Sony

ICD-MS1

1.75" x
4.25" x
0.667"

Cost

PC
Interface

Stereo/
Mono

129.95

Mono

ICS (Sony
ADPCM)

89.95

Mono

ICS (Sony
ADPCM)

299.95

Line Out
Only,
Parallel
port PCcard
reader or
PCMCIA
card
adapter
available
for Stick
Media

Mono

MSV
(Sony
ADPCM)

Sillacom

Clue 240

5.1" x 1.2"
x .65"

2 oz

Sillacom

Clue 480

5.1" x 1.2"
x .65"

2 oz

Sillacom

Clue 560

5.1" x 1.2"
x .65"

2 oz

Voice-It

VT-90

3.5" x
2.25" x
0.33"

2 oz

LP:233
min
SP:116
min
LP:506
min
SP:231
min
LP:556
min
SP:255
min
1.5 min

2 AAA

129.00

Line Out
Jack

Mono

2 AAA

150.00

Line Out
Jack

Mono

2 AAA

165.00

Line Out
Jack

Mono

4 CR2025
Lithium
Cells

39.00

Mono

Voice-It

VT-300

3.5" x
2.25" x
0.5"

2 oz

5 min

1 AAA

55.00

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

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

Serial or
USB

Mono

2 AAA
3.1 oz (w/
LP:131
batt)
min (8kHz (3V), 5 hr
record
samp)
SP:63 min
(11kHz
samp) w/
16MB
Stick

Nom.
Bandwidth
SNR (dB)
280Hz2.8kHz

SP:240Hz4.8kHz
LP:240Hz3.2kHz

Dynamic
Range

118.00

Voice
Sample
Encoding Freq / Bit
Rate
6.5kHz

SP:11kHz
LP:7kHz

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).
Maker

Model

Sony

ICD67
ICDV21
ICDMS1

Sony
Sony

Sillacom

Time/
Date
Stamp
Yes

Mic
Ext/Int

Removable
Memory?

Int

Built in IC
Flash
Built in IC
Flash
Yes,
Memory
Stick media

No
Yes

Both

Memory
Size
(MB)

Notes

URL

Hi/Lo Mic,
Hold Switch

http://www.sel.sony.com/SEL/consumer/icrecorder/features_comparison.html
http://www.sony.com/

8MB to
64MB
Memory
Stick
Media
(256MB
under
development)

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/

Clue
240
Clue
480

Built in IC

http://www.zap1.com/comparisons.html

Built in IC

http://www.zap1.com/comparisons.html

Sillacom

Clue
560

Built in IC

http://www.zap1.com/comparisons.html

Voice-It
Voice-It

VT-90
VT300
VT700
VR1000

Built in IC
Built in
Flash
Built in
Flash
Both, Built
in Flash
plus
memory
card slot

http://www.zap1.com/comparisons.html
http://www.zap1.com/comparisons.html

Sillacom

Voice-It
Voice-It

http://www.smoltz.com/
Has slot for
additional
SSFDC
memory card

http://www.smoltz.com/

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).
Maker

Model

Size

Record
Time

Power
Needs

Voice-It

VX-1200

3.5" x 2.5"
x 0.75"

2 oz

12 min

Voice-It

VX-3400

3.5" x 2.5"
x 0.75"

2 oz

LP:34 min
SP:23 min
HQ:17 min

Voice-It

VTR-3200

4.75" x
2.25" x
1.0"

3.5 oz

Voice-It

VM-15

4.24" x
2.25" x
0.75"

3.8 oz

22 min

Voice-It

VM-30

4.24" x
2.25" x
0.75"

3.8 oz

Univex

SPD25U/ 113mm x
55mm x
100U
14mm
Voica
digital
recorder
4" x 1.375"
8-hour
Voice
Recorder

Nom.
Bandwidth
SNR (dB)

Dynamic
Range

Cost

PC
Interface

Stereo/
Mono

1 AAA

71.00

Mono

1 AAA

79.00

Mono

200.00

Serial,
16.7-33.3
kbps

Mono

AAA

88.00

45 min

AAA

98.00

58g

25-100
min (2 to
8 MB)

2 AAAA

289.00

Yes

502 min

2 AAA, 10
hr record

64 g w/o
batt

120min
record
time

LP:74 min 2 AAA, 10
SP:55 min hr record
HQ:40 min

199.95

Yes

MP3
Creative
Labs

NOMAD
64

85mm x
58mm x
17mm

2 AAA (5
hrs play
time)

>90 dB

20Hz 20kHz MP3

202.95

Parallel

Voice
Sample
Encoding Freq / Bit
Rate

LP:6kHz
SP:8kHz
HQ:11kHz

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).
Removable
Memory?

Memory
Size (MB)
?

Both

Built in
Flash
Built in
Flash
Both, 4MB
Int Flash,
expandable
w/ 2/4/8MB
Cards

Notes

URL

Model

Voice-It

VX-1200

Voice-It

VX-3400

Voice-It

VTR3200

Voice-It

VM-15

Built in

Voice-It

VM-30

Built in

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

Voice
activated?
Has 16MB
flash memory

http://www.lifestylefascination.com/

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

MP3
Creative
Labs

Time/
Date
Stamp

Mic
Ext/Int

Maker

Yes

http://www.zap1.com/comparisons.html

?
4 Int Flash,
2/4/8 Cards

http://www.zap1.com/comparisons.html
HQ mode
recommended
for voice-totext 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.
Automatic
phone dialing
Automatic
phone dialing

http://www.zap1.com/comparisons.html

http://www.zap1.com/VM-30homepage.html
http://www.zap1.com/VM-30homepage.html

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).
Maker

Model

Size

Record
Time

Power
Needs

Creative Labs

NOMAD II

1 AA, 1.5V
Up to
65mm x 88 g
(10 hrs play
240min
93mm x w/o batt
time)
record time
21mm
on 64MB
SmartMedia

Creative Labs

NOMAD II
MG

Up to
58mm x 77.1 g
240min
90mm x w/o batt
record time
18mm
on 64MB
built-in
memory

eGO

i2GO

Varo Vision

Nom.
Bandwidt Dynami
SNR (dB)
h
c Range

Cost

PC
Interface

Stereo/
Voice
Mono Encoding

Sample
Freq / Bit
Rate

>90 dB

20Hz 20kHz
MP3

399.95

USB or opt.
Docking
station

Proprietar 8kHz, 16y G.721 4- bit record
prior to
bit
ADPCM
ADPCM
@ 32kbps encoding

2 AAA (10
hrs play
time)

>90 dB

20Hz 20kHz
MP3

799.99

USB via
Docking
station

Proprietar 8kHz, 16y G.721 4- bit record
prior to
bit
ADPCM
ADPCM
@ 32kbps encoding

64MB
(240min),
96MB,
170MB,
340MB

2 AA

90dB

20 - 15kHz

219 - 399

USB

VaroMan

130min
Voice

1 AA, 1.5V
(12 hrs play
time)

90dB

Parallel

ADPCM
Voice

VaroMan II

130min
Voice

2 AAA

90dB

USB

ADPCM
Voice

2.75" x
1.25" x
4.5"

7 oz

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).
Removable
Memory?

Memory
Size (MB)

Notes

NOMAD
II

Removable
SmartMedia
only

64 Max

Creative
Labs

NOMAD
II MG

Both, Built
in Flash
plus
Smartmedia
Flash slot

64 Int,
16/32/64
Smartmedia
Cards

eGO

i2GO

Both, Built
in Flash
plus Flash
card slot
plus ext
hard drive
capability

64, 96,
170(HD),
340(HD)

Varo
Vision

VaroMan

Int

Both, Built
in Flash
plus
Smartmedia
Flash slot

32 Int,
16/32
Smartmedia
Cards

Varo
Vision

VaroMan
II

Int

Both, Built
in Flash
plus
Smartmedia
Flash slot

32/64 Int,
16/32
Smartmedia
Cards

"SDMI
compliant".
Uses
removable
flash memory
cards (64 MB
max). Has
FM Tuner.
Plays MP3,
WMA format
music.
"SDMI
compliant".
64MB built-in
int. memory
plus
removable
SmarMedia
Card slot (64
MB max).
Has FM
Tuner. Plays
MP3, WMA
format music.
MP3 Player
with several
memory
options in the
form of
compact flash
cards.
Approximately
1MB for 4
minutes of
recording
MP3 Player &
Voice
Recorder.
32MB =
130min voice
recording
time. Built-in
mic. Built-in
32MB,
expandable
by 16/32MB
SmartMedia
Card.
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.

Maker

Model

Creative
Labs

Time/
Date
Stamp

Mic
Ext/Int

URL

http://www.layer3.org/devices/portables.html

http://www.varovision.com/sub1/vman.html

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).
Maker

Model

Varo Vision

VaroMan
Plus

Varo Vision

VaroMan
Super

Sensory
Science

Size

Record
Time

Power
Needs

170min
Voice on
40MB Clik!
disk

LiIon
Recharge
(12 hr play
time)

90dB

raveMP
2000

1 AA, 1.5V
70g,
120min
2.67" x
3.7" x w/o batt Voice on (10 hrs play
time)
32MB built.67"
in memory
only

70dB

20Hz 20kHz

50.00

Parallel (up Mono
to 150kbps Voice
Record
R/W)

ADPCM
Voice,
MP3
Music

Voice:
LP:33kbps/
8kHz
SP:66kbps
/ 16kHz
HQ:132kbp
s/ 32kHz

Sensory
Science

raveMP
2100

1 AA, 1.5V
70g,
240min
2.67" x
3.7" x w/o batt Voice on (10 hrs play
time)
64MB built.67"
in memory
only

70dB

20Hz 20kHz

189.99

Parallel (up Mono
to 150kbps Voice
Record
R/W)

ADPCM
Voice,
MP3
Music

Voice:
LP:33kbps/
8kHz
SP:66kbps
/ 16kHz
HQ:132kbp
s/ 32kHz

Sensory
Science

raveMP
2200

1 AA, 1.5V
74g,
240min
2.26" x
3.29" x w/o batt Voice on (10 hrs play
time)
64MB built.68"
in memory
only

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"

LiIon
150min
mono Voice, Recharge
(12 hr play
75min
time)
stereo
Music on
40MB Clik!
disk

90dB

20Hz 20kHz

299.00

USB (up to
350kbps
R/W), Clik!
Disc (up to
1Mbps)

Mono
Voice
Record

Voice:
ADPCM
LP:33kbps/
Voice,
8kHz
MP3,
Microsoft SP:66kbps
/ 16kHz
WMA4,
HQ:132kbp
AAC
s/ 32kHz
Music

Audio Request

Ondigo

66mm x
90mm x
18mm

249.95

Parallel
(2Mbps
max)

7.4 oz

4 hrs Max

2 AAA (10
hrs play
time)

Nom.
Bandwidt Dynami
SNR (dB)
h
c Range

Cost

PC
Interface

Stereo/
Voice
Mono Encoding
ADPCM
Voice

Parallel,
USB
optional

90dB

Sample
Freq / Bit
Rate

ADPCM

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).
Maker

Model

Varo
Vision

VaroMan
Plus

Varo
Vision
Sensory
Science

VaroMan
Super
raveMP
2000

Sensory
Science

Time/
Date
Stamp

Mic
Ext/Int

Removable
Memory?

Memory
Size (MB)

Notes

Int

Removable
40 MB Clik
Discs Only

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).
Not yet
available.
MP3 Player
with 32MB
built in
memory
(expandable
to 64MB w/
32MB Flash
Memory
Card) and
built in mic
MP3 Player
with 64MB
built in
memory
(expandable
to 96MB w/
32MB Flash
Memory
Card) and
built in mic
MP3 Player
with 64MB
built in
memory
(expandable
to 126MB
w/ 64MB
SmartMedia
Card) and
built in mic
MP3/WMA
Player with
0MB built in
memory
and built in
mic; ZDNet
review
claims
"muted &
fuzzy" voice
record
MP3 player,
FM tuner,
250 number
phone
directory,
SmartMedia
expansion
slot.

Yes

Int,
Line In

Both, Built
in Flash
plus Flash
slot

32 Int,
16/32 Flash
Cards

raveMP
2100

Yes

Int,
Line In

Both, Built
in Flash
plus Flash
slot

64 Int,
16/32 Flash
Cards

Sensory
Science

raveMP
2200

Int

Both, Built
in Flash
plus Flash
slot

64 Int,
16/32/64
Flash Cards

Sensory
Science

raveMP
2300

Int

40 MB Clik
Discs

Audio
Request

Ondigo

Both, Built
in Flash
plus
Smartmedia
Flash slot

64 Int,
SmartMedia
Slot

URL

http://www.varovision.com/sub1/vman.html

http://www.varovision.com/sub1/vman.html
http://www.layer3.org/devices/portables.html

http://www.layer3.org/devices/portables.html

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).
Maker

Model

Size

Record
Time

Power
Needs

JazPiper

MV32P

66mm x
90mm x
18mm

74g

32MB or 2
hrs (exp to
64MB)

2 AAA (10
hrs play
time)

JazPiper

MVR64P

66mm x
90mm x
18mm

74g

64MB

D-Link

DMP-100

85mm x
62mm x
17.5m
m

62g
(w/o
batt)

Over 120
min Voice

2 AAA, 3V
(10 hrs play
time)

90dB

D-Link

DMP-110

89mm x
65mm x
17mm

80g
(w/o
batt)

Over 120
min Voice

2 AAA, 3V
(10 hrs play
time)

D-Link

DMP-120

89mm x
65mm x
17mm

80g
(w/o
batt)

Over 120
min Voice

D'Music SM- 63mm x
320V
85mm x
17.5m
m

62g
(w/o
batt)

65mm x
87mm x
17.2m
m
65mm x
87mm x
17.2m
m
3.3" x
2.5" x
0.7"
3.125"
x
2.875"
x
0.6875"

Pine

Samsung

YP-E32
(Yepp32)

Samsung

YP-E64
(Yepp64)

AudioVox

MP3000

Nom.
Bandwidt Dynami
SNR (dB)
h
c Range

Cost

PC
Interface

Stereo/
Voice
Mono Encoding

Sample
Freq / Bit
Rate

169.00

Yes

249.00

Yes

20Hz 20kHz

139.00

Parallel

Mono
Voice
Record

24kbps 256kbps

90dB

20Hz 20kHz

149.00

USB
(12Mbps
transfer)

Mono
Voice
Record

24kbps 256kbps

2 AAA, 3V
(10 hrs play
time)

90dB

20Hz 20kHz

199.00

USB
(12Mbps
transfer)

Mono
Voice
Record

24kbps 256kbps

135 min
Max Voice

2 AAA, 3V
(10 hrs play
time)

90dB

20Hz 20kHz

169.99

Parallel

Mono
Voice
Record

MP3?

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

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

2 oz

64MB +
64MB MMC

2 AAA (14
hrs record
time)

149.99

Parallel

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)

399.95

PCLink opt
(USB to
Optical
Digital Line
In); Line
Out to PC;
Both RealTime Only

Both

ATRAC

90dB

24kbps 256kbps

MINIDISC
Sony

MZ-R90

20-20kHz

44.1kHz

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).
Removable
Memory?

Memory
Size (MB)

Notes

MV32P

Both

MP3 player.

http://www.layer3.org/devices/portables.html

JazPiper

MVR64P

Both

http://www.layer3.org/devices/portables.html

D-Link

DMP100

Int

Both, Built
in Flash
plus
Smartmedia
Flash slot

32 Int,
16/32
Smartmedia
Cards

D-Link

DMP110

Int

Both, Built
in Flash
plus 3.3V
Smartmedia
Flash slot

32 Int,
16/32
Smartmedia
Cards

D-Link

DMP120

Int

Both, Built
in Flash
plus 3.3V
Smartmedia
Flash slot

64 Int,
16/32/54
Smartmedia
Cards

Pine

D'Music
SM320V

Int

Both, Built
in Flash
plus 3.3V
Smartmedia
Flash slot

32 Int,
16/32
Smartmedia
Cards

Same as
MV32P
except has
64MB built
in, and has
FM tuner
and "3D
Audio".
32 MB built
in Flash
Memory.
Smartmedia
slot allows
expansion
by 32 MB.
32 MB built
in Flash
Memory.
Smartmedia
slot allows
expansion
by 32 MB.
64 MB built
in Flash
Memory.
Smartmedia
slot allows
expansion
by 64 MB.
Smartmedia
slot allows
expansion
by 32 or 64
MB to 32
MB built in;
10 MHz/8bit
CPU

Samsung

YP-E32
(Yepp32)
YP-E64
(Yepp64)
MP3000

Int

Both

http://www.layer3.org/devices/portables.html

Int

Both

http://www.layer3.org/devices/portables.html

Both

http://www.layer3.org/devices/portables.html

Maker

Model

JazPiper

Samsung
AudioVox

Time/
Date
Stamp

Mic
Ext/Int

URL

http://www.dlink.com/products/DigitalHome/DigitalAudio/

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/

Table A-1. Commercial Off-The-Shelf (COTS) Products (continued).
Maker

Model

Size

Record
Time

Power
Needs

Nom.
Bandwidt Dynami
SNR (dB)
h
c Range

Cost

PC
Interface

Stereo/
Voice
Mono Encoding

Sample
Freq / Bit
Rate

Sony

MZ-R70

3.1875"
x 3" x
1"

4 oz
(w/o
batt)

74min
stereo,
148min
mono

1 AA (17 hr
play time)
or 1 NCWMAA
NiMH (6.5
hr play
time)

20-20kHz

279.95

PCLink opt
(USB to
Optical
Digital Line
In); Line
Out to PC;
Both RealTime 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 RealTime Only

Both

ATRAC

44.1kHz

Sony

MZ-B3

5.25" x
1.125"
x
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

1699.95

Line In/Out
Only

Stereo

NT
Format,
LDM-2
Modul

32kHz, 12
bit
nonlinear
(equiv to
17 bit)

DAT
Sony

NT2

1 AA (5 hr
4.375" 5.75 oz 60 or 120
min per tape record time)
x 0.94"
& 1 CRx 2.5"
1220 Li
Button

>80dB,
Line In

1014.5kHz

>80dB

Table A-1. Commercial Off-The-Shelf (COTS) Audio Recorder Products (rightmost columns) (continued).
Time/
Date
Stamp
No

Mic
Ext/Int

Removable
Memory?

Memory
Size (MB)

Notes

Ext

Minidiscs

74/148 min

MZR37SP

Ext

Minidiscs

74/148 min

MZ-B3

Yes

Both

Minidiscs

74/148 min

Mini-disc
player/
recorder.
Mini-disc
player/
recorder.
Mini-disc
player/
recorder.
VOR
capable.
Built-in Mic.

NT2

Yes

Ext

Removable
Casette
Tape

60/120 min

Maker

Model

Sony

MZ-R70

Sony

URL

http://www.sony.com/

DAT
Sony

Microcassette
player, tape
speed
6.35mm/sec

http://www.sony.com/

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
16 bits (but, may not get large dynamic ranges)
Bandwidth (kHz)
16
implies
32000 samples/sec
record time (min)
120
implies 3.686E+09 bits of storage
460.8 Mbytes of FLASH
compression ratio
2
implies
230.4 Mbytes of FLASH
size (square inches surface area)
12.47
up to half 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
mic amp (AD8551ARM in RM8)
smt resistors (amp,anti alias filt)
smt caps (amp, anti alias filt)
24 bit delta sigma (store 16) CS5333
Prog Logic (XCR3032XL-10CS48C)
DSP (TMS320VC5502)
DSP Equiv 3.3V current for 1.5V
start button
CompactFlash256
Flash holder
oscillator (ECS3953M-100-B)
DC/DC 3.3V (LTC1877EMS8)
DC/DC 1.5V (LTC1877EMS8)
battery holder
battery (AAA Alkaline)

1
1
3
3
1
1
1
1
1
1
1
1
1
1
3

0.048
0.012
0.008
0.060
0.076
0.349

0.000
0.048
0.037
0.024
0.060
0.076
0.349

0.000
7.165
7.165
0.000
0.058
0.058
0.023
0.023
0.023
0.023
0.000
0.656
1.969
9.831
excldg mic

0
1
0
0
30
10
20
22.7
21

0
1
0
0
30
10
20
22.7
0
21
0
0
0
0

1150mAh
105.2273

$ 1.89
$ 0.27
$ 0.42
$ 4.43
$ 2.30
$ 10.00
$
$102.00
$
$ 2.78
$ 2.96
$ 2.96
$ 0.70
$ 0.70

$
$
1.89
$
0.81
$
1.27
$
4.43
$
2.30
$ 10.00
$
$ 102.00
$
$
2.78
$
2.96
$
2.96
$
0.70
$
2.10
$ 136.64

APPENDIX C
BODY WIRE PRODUCT SOURCE MATRIX

COMPANY
NAME

STREET
ADDRESS PHONE
P.O. Box 704
Hunt Valley,
410MD
584Accuquest
Corporation 21030
2355
193 Vacquero
Dr.
303Boulder, CO
499AMC Sales 80303
5405
12301 NW 39th
St.
Audio
954Intelligence Coral Springs, 255Devices, Inc. FL 33065
2619
44-0116247060
Bugs &
Things
UK
6
CCS
International
Counter Spy
Shop
Rotterdam
Clayton Wood
Close, West
Park
Datong
Electronics Leeds, UK
Limited
LS166QE
75
Northeastern
Blvd.
DTC
Communicati Nashua, NH
3062
ons, Inc.
4141 Avenida
Global
de la Plata
Microwave
Oceaside, CA
92056
Systems
P. O. Box 37
Harris
Melbourne, FL
Corporation 32902
11840 N.W.
41st Street
Innovative
Surveillance Coral Springs,
Technology FL 33065

FAX

PRODUCT

4105842356

8009262488

mini
microphone

narrow band
transmitters

44-011624706 www.ukinternet04
marketing.co.uk/bugsnthings

mini
microphone

31-102909688 www.counterspyshop.com

pen transmitter

donna.eagle@waida.com

44 113
2744
822

6038804411

(M) Mfr
(D) Distrb
(N) NATIA

N
www.dtccom.com
603880- http://www.epgctac.com/audi
6965 o.htm

7606318021
4077276079

7606318031 gms.gmsinc.com

9547550724

9547550817 teamist@aol.com

audio
transmission
equipment

miniature
surveillance
equip.

audio
surveillance
equip.

Intelligence
Support
Group, Lt.
ISIS
Surveillance
Sytems and
Equipment
Co, Inc.

various
locations

7603775013

7603775073 from site onlu

P.O. Box 577 903903Tyler, TX
53353375710
1712
1713
100A Hunter
Law
Place
919919Enforcement Youngsville,
554556Associates
NC 27596
4700
6240
P. O. Box
510567
M3 Media
941941Consultants, Punta Gorda, 575575Inc.
FL 33951
7007
2727
4749-C Bennett
Drive
925925Livemore, CA 449449Premier
Wireless, Inc. 94550
2101
9148
574 Meacham
Ave.
Probity
516516Electronics Elmont, NY
775355Inc.
11003
3275
0225
Schell
120 N. Lincoln 316316Electronics, Chanute, KS
431431Inc.
66720
2350
2365
Corby Road,
Weldon
Corby,
Security
44
44
Northants, UK 153640 15362
Research
Ltd.
NN173AR
0988
66711
Special
Electronic
Security
Products, Ltd.
3389 Sheridan
St., Suite 156 954954Spectronic
Hollywood, FL 35935933021
Systems
9847
9857
1-888Spy City
Spy-City
8777790007
Spy
403Equipment
237Store
8130

surveillance
equip.

body worn
surveillance
systems

audio
surveillance
systems

covert
surveillance
audio equip.

body worn
transmitters

probityelec@hotmail.com

N,M,D

body
transmitters

www.chanuteks.com/schell

N,M,D

surveillance
transmitters

marketing@securityresearch.com

N,M,D

surveillance
equipment

radome1494@aol.com

NMD

lea2@mindspring.com

m3papy@aol.com

hardwire audio
systems
body
transmitters

body
transmitters

N,M

covert
transmitters

SpyZone
965 Shulman
Ave.
Santa Clara,
Swintek, Inc. CA 95050

4087274889

4087273025

465 Herndon
Pkwy.
Herndon, VA
Systems
Wireless, Ltd. 20170
1701 Second
Tactical
Ave.
Technologies Folsom, PA
, Inc.
19033
7483 B
Candlewood
Tektron Micro Rd.
Electronics, Hanover, MD
21076
Inc.
6 Halapid St.
Teletron Ltd. Petack
The Global various
Spy Shops
locations
The Spy
Shop
2627 West
Railway St.
The Spy
Abbosford, BC
V2S2E6
Store
64 Granville
Park, Blacrock
Audio Visual Co. Dublin
Security Ltd. Ireland
Employers
Asset
Protection
Raleigh, NC
250 Portland
Road
Hove Sussex,
Bull Electrical UK BN35QT
P.O. Box 8681
Lexington, KY
Kubies
Electronics 40533
5023 Camp
Bowie Blv.
Ft. Worth, TX
The Spy
Connection 76107
3811 Schaefer
Ave. Ste. I
Chino, CA
Spygate
91710
360 Madison
E-Spyzone Ave. 6 FL
(part of CCS New York, NY
Int'l)
10017
716 Lea Bridge
Road
Lorraine
Electronics London, UK
Surveillance E106AW

7034717887

7034371107

6105220106

6105229430 rsnyder459@aol.com

4108504200

4108504209 tmei@erols.com

N,M

body wires

N,M

digital stereo
audio
equipment

M
globalspy.com

from site only

mini transmitter
pen
microphone
mini
microphone

pen
microphone

mini transmitter

micro-pen

mini transmitter

electronicsabc@mindspring.
com

mini mic

www.thespyconnection.com

mini mics (tie
clip)

6048594769

6048592799

353-012870055
8883405874
44-0870740463
5

353-012870056 alan@avsecurity.com
9192501998 www.eaprotection.com
44-0127332307
www.bullnet.co.uk
7

8777792666
9095171107

9095171105 sales@spygate.com

2125573040

2129831316 information@e-spyzone.com
44-044-0-20- 208558- 85584226
1338 salesinfo@lorraine.co.uk

M,D

mini mic

pen, mini mic

pen mic, mini
trx

Spy Supply
Online

www.spysupplyonline.com

8519-8521 W.
Sunset Blvd.
Spy Tech
W Hollywood,
CA 90069
Agency
41527-923,
12th Street
Cyber Gold New
(Golden West Westminster,
Investigative BC Canada
Group, Ltd.) V3M1K0

Spymaster
Advanced
Intelligence
Co. Ltd.
USA Online
Services, Inc.
2500 Old
Alabama Rd.
SpyMarketpla Roswell, GA
30076
ce

Spy Surplus
Micro
Electrical

Audiotel
International
Ltd.
IBH-IMPEX
ELEKTRONI
K GMBH
ATET
Telematica
radiotelecom
unicazioni

Elvira
Production
Firm
JSC "Grant Systems &
Technologies
"

3106576333

3106578714

surveillance
mics

6043188545
972-89362304

6045214085 www.cyber-gold.com

mini
microphone

same gmelnick@spymaster.co.il

body wire trx.

8004902723
8002690718

7706406752 spy@spymarketplace.com
8184755330 www.spysurplus.com

mini
microphone

body wires,
pen mic

pen mic

www.microelec.com
Cavendish
Courtyard,
Sallow Road
Corby, England
NN175DZ
Friederikenplat
z 55
Dessau
6844
V.G. da
Verrazzano 42
Torino, Italy
10129
Gidrogorodok,
Korpus A
Moscow
Region,
Zheleznotorozh
ny, Russia
143980
Parkovaya 9th
Str 53
Moscow,
Russia 105215

mini
microphone,
pen

01536- 01536
26-66- -2677
67-11
0340- 0340240-02- 24042
02-44
3939-011- 01156-83- 59-04info@atet.it
93
200

7-095522769
same firm_elvira@hotmail.com
1

464-04same gstech@cityline.ru
81

Security
Search Product
Sales - P.O.
Box 14237
303PK Electronic Denver, CO
2337854
International 14237

Twitco
Distributing
CovertSystems.com
By Ross
Associates

PO Box 239
Rindge, NH
03461
2495 Vista
Drive
Upland CA
91784

6038999800

603- ewp@twitco.com
899- http://www.mv.com/ipusers/t
9802 witco/

9099818855

909- sales@covert-systems.com
981- http://www.ross.cc/index.htm
7386 l

Earphones,
Microphones,
Covert
shrouds,
Headsets,
Tactical
Equipment

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.

Table D-1. Body Worn Recorder Survey Responses.
Our department uses body worn voice recorders on average ________ days a month.
Survey #

Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

10
1
0

8
30
10
1
1
0
20
20
0
0
0
1
0

1
30
2
0.5
?

n/a
n/a
5
20
0
30

22
0
6
0
0
1
0
1
0
30

0
0
0
0
10
1
1
n/a
0
20
0

Our department uses body worn voice recorders for the following types of operations.
Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50

Officer buys (backup)

Informant Buys (backup)

Crimes against person

Drug Offenses

arson

Property Crime

Narcotics
Narcotics
Drugs
Drug Buys
Felonies
Drug Investigations
Narcotic Buys
Undercover

Robbery/Homicide
Prostittution

Burglary Investigation
Intelligence Gathering

Sexual Assault

Alcohol Buys
Any Drug Cases

Narcotics

Personal Crimes

drugs

Robbery/Homicide

interviews

Traffic Stops

Drug Case

Prostitution Cases

Drugs
Narcotics
Narcotics
Narcotics
Major Crimes
Intelligence

Intel Work
Vice
Gambling
Gambling
Demo

Narcotics
Traffic Stops

Callout Response

Impromptu Telephone Monitor

Officer Protection

Interview/Investigation

Investigate Officer Complaints

Prostitution

Prostitution
Integrity

White Collar

Court Purposes

51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

CI Drug Purchases

U/C Drug Purchases

Intelligence Gathering

Assist CID

Undercover Drug Operations

n/a
0
Drug Investigations

Stolen Property

Intelligence Gathering
Patrol

Interviewing

Narcotics
n/a
Narc
Narcotics

other
guns

Assaults

Drugs

Burglary / theft

Sexual Crimes

Undercover

Drug Investigations

n/a

Threat Complaints

Our department owns _______ body worn voice recorders.
Survey #

Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

4
1
0

1
20
1
1
1
1
12
6

7
0

3
4
2
0
1

2
5
1
6

12
0
1
0

2
2
2
40

0
0
6
2
1

20
2

We require a minimum recording time of ___ minutes per use or ___ hours per operation.
Survey #

Minutes
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

Hours

Survey #

60
60

90
60
60

2
2
1
60

90
n/a

n/a

1.5

120
120

Minutes
Hours
41
42
43
60
1
44
don't require
45
46
47 All contacts on assigned shift
48
49
50
51
90
3.5
52
53
90
8
54
55
56
57
58
2
59
60
90
61
62
60
63
64
65
66
67
68
69
60
70
60
71
72
60
1
73
74
75
76
77
none set

Our Department stores the recordings for (days\weeks\months\years)
Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

Days Weeks

Months

Years
5
forever

2
Trial/Appeals
As Long as Needed

x
x
x

x
Till case is over
x
5

3
1

indefinite

Survey # Days Weeks
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

90
1

Months

Years

x
1

case by case basis

5
10

7
until case is tried
1
depends on situation

Our Voice Recorders are (mini-casstte) (solid state) type
Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

Mini Cassette

Solid State

x
x

Digital
x

x
x
x

x
yes

x
x
x
x

x
x

Survey #
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

Mini Cassette

Solid State

x
x

I Wish

x
x
x
x

x
x
x

x
x

We use Voice Recorders for:

Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

Officer
Protection

Intelligence
Gathering

Testimony
Support

y
y
y
y
y
y

y
y
y
y
y
y
y

y
y
y
y

y
y

y
y
y

y
y

y
y
y
n

y
y
y
y

Survey #
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

Officer
Protection

Intelligence
Gathering

Testimony
Support

y
y

Our Voice Recorders are:

Survey # Dept Issued
1
2
x
3
4
x
5
6
7
8
9
x
10
x
11
x
12
x
13
x
14
x
15
x
16
x
17
18
x
19
20
21
x
22
23
24
x
25
26
27
28
29
30
31
x
32
33
34
x
35
x
36
x
37
x
38
39
x
40

Personal
Purchase

x
x

Survey #
Dept Issued
41
42
43
x
44
x
45
46
47
x
48
49
50
51
x
52
53
54
55
56
57
x
58
x
59
60
x
61
62
x
63
64
65
66
67
68
69
x
70
x
71
72
73
74
75
x
76
77
x

Personal
Purchase

Please rank the following items from 1-8 (1 most imprtant)

Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48

Size

Record Time

Battery Life

Packaging

Mike
Sensitivity

Cost

Voice
Operated

Operating
Controls

2
1
4
1
5
1
1
1

4
3
7
3
3
2
2
3

5
5
8
5
4
3
3
6

1
2
1
7
2
8
8
2

2
4
2
4
1
4
8
4

4
7
5
8
8
5
6
8

6
8
3
2
7
7
7
5

5
6
6
6
6
6
4
7

3
1

6
2

2
7
8

8
7

3
5
3

1
1
5

5
6

4
4

1
1
4
1

3
3
3
2

5
5
2
6

2
2
5
4

4
6
7
5

6
4
6
3

7
8
8
7

8
7
7
8

8
6

8
8

8
5

8
7

8
4

8
3

1
2

8
1

49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

4
1
1

5
3
2

1
2
3

3
4
4

2
5
5

8
7
7

7
8
8

6
6
6

1
3

5
1

7
2

3
4

2
7

4
5

8
8

6
6

4
4

1
7

3
6

5
3

2
1

7
8

8
5

6
2

The courts in our area (allow) (don't allow) voice recording of ofcr interviews as evidence.
Survey #

Allow
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

Don't Allow

Survey #

Allow
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

x
x

x
x
x
x
x
x

x
x
x

x
x
x
x
x

x
x

x
x
x

x
x
x
x

x
x
x

x
x

Don't Allow

What improvement would you like to see in your current voice recorders?
Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47

Mike sensitivity - quality & operating controls

Concealment
Digital recorders offer best convenience, size, and clarity

More recording time and better mic sensitivity,

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.
Voice quality - voice freq improvement

lower cost for better units
Ability to reduce or eliminate motor noise in recording/playback

ability to record without mic having to be at neck level

Smaller, better mic

cost

Smaller, more concealable
Clarity, Reliability (sturdiness)

ease of one touch controls, recording quality & time. Size of unit.

48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

Be Digital
Longer recording time. Better Recordings. Digital Recorders.

I would like the recorders to be easier to conceal
n/a

easy concealment, clarity

Size
would like to see full range of products & how they can be used in the field.

COMMENTS
Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

23
24
25
26

27
28
29
30
31
32
33
34
35
36
37
38
39
40

The body wire/repeater/recorder that we currently use is ver user friendly. Has many features and the recordigs are
clear and easily understood.
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.

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.

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.

Dream: To have equipment that always works.

Thank you for the opportunity to complete this survey.
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.

41
42
43
44
45
46
47
48
49
50

51
52
53
54
55
56
57
58
59
60
61
62
63
64
65

66
67

68
69
70
71

72
73
74
75

76
77

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.
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.

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.

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.

Table D-2. Body Worn Transmitter Survey Responses.
Average use of body wires per month.
Survey #

Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

8
30
0
1
6
1
0
0
8
60
10
1
1
15
20
20
8
8
2
1
1
16
0
20
10
31

1
15
14
Very Often
6
30
8
5
?

41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

72
20
25
2
0
10
n/a
10
1
32
5
0
8
1
30
3
12
0
20
2
0
10
3
2
1 Undercover use everyday
30
30
2
1
2
50
n/a
2

Illegal Narcotics
Officer Buys
Narcotics Crimes
Crimes against Persons
Narcotics

n/a
Narcotics
Narcotics
Drug
Drugs
Felonies
Drug Investigations
Narcotics Buys
Undercover
Drug investigations
Narcotics
Narcotics
Narcotics
Drug
Drug
Bike Patrol
n/a
Drunk Driving Stops
Narcotics
General Patrol

Delivery Stings
Officer Buy/Bust
Serious Felonies
Drug Offenses
Stolen Property

Gather Info
Informant buys

Informant buy/bust

Arson

Property Crimes

Burglary Investigations
Prostitution
Alcohol Stings
Alcohol
Drug Cases
Prostitution
Prostitution

Homicide Invest
Money Laundering

Sexual Assault Invest
Informants in other crimes

Personal Crimes
Major Crimes

Prostitution

Property Crimes

Robbery
Alcohol Compliance
Tavern Walk Thru

Other Criminal
Narcotics Surveillance

Patrol/Criminal Patrol
Domestic Abuse

Invest Interviews
Assault

Narcotics Purchase
Drug Cases
Narcotics

Officer Protection
Prostitution
Burglary/Stolen Property

Sex Crimes

Drugs
Narcotics
Narcotics
Narcotics
Major Crimes
Survey

Intel work
Vice
Prostitution
Gambling
Robberies
Demo

Crime Invest

Gambling
Burglary
Intellig gathering

Narcotics
Narcotics
Narcotics
Drug Invest

Stings

Informants

Sex Crimes

Inmate Contacts

Undercover Narcotics

Prostitution

Vice

Drug Operations

Sexual Assault

Sexual Abuse Minor

Drug

Property Crimes

Burglary/Theft

51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

CI Drug Purchase
Drugs

U/C Drug Purchaces
Burglary
Stolen Property

Homicide Invest
Vice

Drugs
n/a
Traffic Stop
Narcotics
Drug Investigations
Drug Investigations
Narcotics
Undercover Drug Buys

DWI/DUI Enforcement

Domestics

Stolen Property
Buying illegal weapons
Thefts
Informant Drug Buys

Murder Investigations
Burglaries
Prostitution Stings

Drug Investigations
Drug

Sexual Abuse of Minors
Property Crimes

Sexual Assault

Hotel Room Surveillance

Gathering Information

Patrol
Other
UC Gun Purchases

Officer Safety

Narcotics Invest
Drug Buys
Drug Investigations
Narcotics
Narcotics
UC Drug Purchase
Drugs
Narcotics
U/C Buys
Drug Investigation
N/a
Narcotics

Theft
Vice
CI Buys
Criminal Invest

Sexual Crime
Officer Safety

Fraud

Vice

CID Investigation

Forgeries

Prostitution Invest

Threat Complaints

Our department owns _______ body wires.
Survey #

Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

2
6
1
1
1
1

41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

0
3
28
1
1
1
4
8
8
3
2
2
2
0
1
0
2
10
2

2
3
2
2
4
4
3
0
?

12
9
2
2
3
1
0
6
11
1
0
2
3
3
2
6
1
2
0
2
3
2
5
12
2
1
0
2
5
0
1

On occasion we borrow body wires Y/N.

Survey #

Other Local
Department State Agency
1
n
n
2
n
n
3
n
n
4
y
5
y
y
6
y
n
7
8
n
n
9
n
y
10
n
n
11
y
y
12
n
n
13
y
14
n
n
15
n
n
16
n
n
17
n
n
18
n
n
19
y
y
20
n
n
21
n
n
22
y
23
n
n
24
n
n
25
n
n
26
y
27
28
29
n
n
30
n
y
31
32
n
n
33
34
y
35
n
n
36
y
y
37
y
y
38
y
39
40

Federal
Agency
y
n
y

Survey #
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

n
n
n
y
y
n
y
n
n
n
n
n
y
n
n
n
n
n
y

n
y
y
n

n
y
n

Other Local
Department State Agency
n
n
n
n
n
y
y

Federal
Agency
n
n
n

y
n
n
n
n
y
n

n
n
n
n
y
n

n
n
n

n
y
n
n
n
n
y
n
n

y
y
n
y
n
n
y
n
n

n
y
n
y
n
n
n
n
n

n
y
n
n
n
n

n
y
y
n
n
y

n
n
n
n
y
n
y
n
n
n

y
n
n
n

We obtain our equipment:
State
Loan from
State
Loan from
Survey
Dept
Agency Procurement State/Fed
Survey
Dept
Agency Procurement State/Fed
#
Purchase Purchase Cooperative Agency Other
#
Purchase Purchase Cooperative Agency
Other
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
x
59
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
67
x
28
68
x
x
x
29
69
x
30
x
70
x
31
x
71
32
x
x
72
x
33
73
x
34
x
74
x
35
x
x
75
x
36
x
76
37
x
77
x
x
38
39
x
40

Our Department uses body wires that operate (y/n)

Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

VHF
y
y
y
y
y
y

UHF

GHZ

Spread
Spectrum

n
n
n

n
n

n
n
n

y
y
y

y
y

y
y
y
y
y

n
y

n
n

n
y

y
n
y
y

y
n
n
n

n
y
n

n
n
n

Survey #
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

UHF
n
n

GHZ
n
n

Spread
Spectrum
n
n

y
y
y

n
n

n
y

n
n

n
y

y
y
n
y
y

n
n
y
n
n

n
n
n
y
n

n
n
n
n
n

y
y

VHF
y
y
y

y
y
y
y
y
n

Our Department owns body wires manufactured by the following companies:
Survey #
1 Tactical Technologies
2 AID
3 Unkown
4 AID / Westinghouse
5 AID
6 AID / Westinghouse
7
8 n/a
9 AID
10 AID
11 Law Enforcement Associates
12
13
14 AID, LEA
15
16 AID
17 AID
18 Unkown
19 LEA, AID
20 AID
21 Tactical Technologies
22 n/a
23 Parmarlow
24 n/a
25
26 TEA
27 Mobile Vision
28
29
30
31 AID
32 AID
33
34
35 TTI and AID
36 ProTech
37 AID and TTI
38 Unkown
39 ?
40

Survey #
41
42 Motorola, LEA, AID
43 AID
44
45
46
47
48 AID & Westinghouse
49
50
51 AID & TTI
52 AID
53 AID
54 N/A
55 TELEX
56
57
58 TTI
59 LEA
60 AID TELEX
61
62 TTI
63 AID
64
65 Dynatech
66 LEA
67 TTI, LEA
68 Mobile Vision
69 AID, LEA
70 DTC
71
72 LEA
73
74
75 AID
76
77

AID
LEA

LEA

When our body wires need repair we:

Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

In-House
Repair

Return to
Send to Local
Manufacturer Radio Shop
x
x
x
x
x
x

Survey
#
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

Other

x
x
x
x
x
x
x
x
x
x
x
x
x
x
x

N/A
x
x
x

x
x
x

x
x
x
x
x
x

In-House
Repair
x

Return to
Send to Local
Manufacturer Radio Shop
x
x
x
x

Other

x
x

x
x
x
N/A
DEALER
x
x
x
x
x

x
x

x
x
x

x
x
x
x

x
x
x
x
x

Please Rank the following items from 1-10 (1 most important)
Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

Mike
Sensitivity
1
2
2
1
3

Built in
Recorder
6
7
8
4
10

7
9
6
10
9
4
7
9
10
5
8
8
6
6

6
4
3
2
1
6
6
5
6
3
1
3
4
3
1

10
6
9
8
7
8
9
8
8
6
10
10
7
8

5
10
4
3
10
3
3
10
5
2
7
7
5
5
6

8
8
10
9
8
7
8
6
7
9
5
9
9
7

8
7
8
7
5
9
10
7
9
8
9
6
10
9

3
2
2
1
3
10
5
3
2
10
4
5
8
4
2

2
7

9
9

6
6
5

7
8

1
1
1

8
10

3
4

10
5
3

2
1
1

8
6
5

10
7
7

4
5
2

9
8
9

3
3
6

7
9
8

6
10
10

5
4
3

1
1
2
1

2
5
1
2

6
7
5
4

10
2
6
7

3
6
4
6

8
9
9
9

4
4
5
5

9
10
7
10

7
8
8
8

5
3
3
3

2
3
8
5

5
2
8
2

4
4
5
6

7
6
8
8

3
5
8
3

8
9
1
7

6
8
8
4

9
7
1
9

10
10
5
10

1
1
8
1

Size
8
5
3
3
2
2

Range
2
1
4
5
4

Battery Life
5
3
4
6
7

Tx Freq
3
10
3
10
5
1

2
1
5
5
4
1
1
1
1
1
6
2
3
1
3

4
3
1
4
2
2
2
2
3
4
2
1
1
2

5
5
7
6
6
5
4
4
4
7
3
4
2
10

4
2
2

5
3
4

1
2
4

Cost
10
6
4
7
6
4

Audio
Encryption Adjustment Packaging
7
4
9
9
8
4
1
6
2
9
8
2
8
9
1
3

50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

6
4
1

2
2
3
2

8
1
5
4

7
9
7

3
3
6
3

5
10
7
8

1
9
8
10

4
8
4
5

9
6
10
9

7
5
1
6

4
7
1
3
4
3

2
1
4
1
1
4

6
2
7
4
5
5

5
10
6
10
7
6

1
4
2
7
6
1

10
8
10
2
8
9

3
6
3
6
3
8

7
5
8
9
10
10

8
9
9
8
9
7

9
3
5
5
2
2

3
1
1
2
3
3
5
3
6

1
4
2
4
1
2
1
1
1

8
3
3
6
6
4
3
2
2

10
8
6
8
10
6
10
5
5

4
6
4
5
2
5
2
4
4

6
10
8
9
8
9
7
9
8

5
7
5
1
4
7
6
7
10

7
5
10
7
7
10
9
6
9

9
9
7
10
9
8
8
10
7

2
2
9
3
5
1
4
8
3

1
1
4
1

1
2
2
2

3
6
3
6

5
10
6
4

1
4
7
7

7
8
10
9

2
3
5
8

1
5
9
5

2
9
8
10

1
7
1
3

We Use Body Wires For:

Survey #

Officer
Protection
1
y
2
y
3
4
y
5
y
6
y
7
8
9
y
10
y
11
y
12
13
y
14
y
15
y
16
y
17
y
18
y
19
y
20
y
21
y
22
y
23
y
24
25
26
y
27
y
28
29
30
y
31
y
32
y
33
34
y
35
y
36
y
37
y
38
y
39
y
40

Intelligence
Gathering
y
y

Officer
Testimony
y
y

y
y
y

y
y
y
y
y
y
y
y
n
y
y
y
y
y
y

y
y
y
y
y
y
y
y
n
y
y
y
y
n

y
y

y
y
y

y
y
y
y
y
y

Survey #

Officer
Protection
41
y
42
43
n
44
n
45
46
y
47
48
y
49
50
51
y
52
y
53
n
54
55
y
56
y
57
y
58
y
59
60
y
61
62
y
63
y
64
65
y
66
y
67
y
68
y
69
y
70
y
71
72
y
73
y
74
y
75
y
76
77
n

Intelligence
Gathering
y

Officer
Testimony
y

y
y

y
y
y

y
y
y
y

y
n
y
y

y
y

y
y
y
y
y
n

y
y
y
y
n

y
y

What improvement would you like to see in your current equipment?
Survey #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47

I'm very pleased with TTI's body Wire
Range & Quality of Recording

Noise Filtering
None

Clarity
Further, Stronger Transmissions
Reliability of signal to cover units
Size
First to obtain additional equipment. To get more range on our transmitter
Better Range and clarity
Smaller, greater range.
Lower cost
Smaller, more audible
Greater Range and battery life
Would like to go digital with repeater system
Simpler Operation
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.
n/a
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
more durability

better clarity with signal
Consistent range without a repeater
Sturdier connection between antenna and plug/connector as well as mic and plug/connector

Range of Transmitter
Overall transmitted voice quality and separation from background noise
size
size
Purchased new wires within 2 months
1 watt in small size and 800 MHz body wire
smaller, more concealable body wires
audio clarity

48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

Encryption on all available transmitters.

To be not detectable by counter-measures (RF-detector/counter, etc) Also be digital.
Updated
Change to cellular transmission or synthesized systems
More Units

I would like it to be smaller and to have a built in digital recorder
n/a
increased transmitter wattage for increased range

Durability
Longer Range, mike sensitivity, battery life
Increased mike sensitivity, more concealable repeater
Range and Durability
Lighter in weight
Make it smaller, easier to conceal, clarity
Frequencies on devices that can't be detected.
Updated concealment covers, better range, more power, smaller size.
Sound quality and range/concealment/we need video, video, video !!!
Better Concealability

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Title                           : Personal Electronics for Law Enforcement Solid State Recorders and Body Wires
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Description                     : NCJ 210488
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Author                          : William Butler, Scott Crowgey, William Heineman, Susan Gourley

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

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