Enping Ding Li Acoustics Technological VHF-4808 Wireless Microphone User Manual VHF 4808

Download:
Mirror Download [FCC.gov]
Document ID	1066851
Application ID	kNXH8+6eDrIzh/+aVQbcgA==
Document Description	Users Manual IV
Short Term Confidential	No
Permanent Confidential	No
Supercede	No
Document Type	User Manual
Display Format	Adobe Acrobat PDF - pdf
Filesize	191.2kB (2390002 bits)
Date Submitted	2009-02-11 00:00:00
Date Available	2009-02-11 00:00:00
Creation Date	2009-02-11 13:21:44
Producing Software	Corel PDF Engine Version 9.397
Document Lastmod	2009-02-11 13:21:54
Document Title	VHF-4808˵Ã÷Êé.cdr
Document Creator	CorelDRAW Version 9.397
Document Author:	΢ÈíÓû§

12
Tips for Acheiving Optimal Performance
Recognizing Interference
The ways of iecogriizmg the type of interference present are observing the RF LED indications and carefully listening to
the audio output A set of headphones can be a useful tool in isolating and analyzing interference problems. With
headphones it is easier to listen to one wireless channel at a time, even when the system is in use.
Below are some interference descriptions Most likely there is one that matches the symptoms that you are experiencing.
- If there is interference when the microphones are off, and noise/distortion is present from the receiver output when the
microphones are on, try turning off all other Wireless microphones. ll the interference problem is still present, there might
be a direct radio interference problem. Direct interference is a serious problem that must be corrected in order for the
wireless system to be fully usable,
' Interference in the form of low level-audio tones. whines, whining sounds whose pitch changes rapidly. or audible voices
or music (distorted or not) is likely to be caused by intermoclulation, non-wireless interference or direct interference.
- If there is interference when the receiver is turned on. in the form of buzzy or raspy whines with a distinct cadence or
rhythm that differs from lime to time, digital interference might be the problem Common sources include computers,
digital delays, effects processors, lighting controllers. and other digital equipment using microprocessors and digital
signal processors (DSPs).
' If there is no interference when the receiver is turned off and irregular popping, cracking or buzzing noises on the audio
with the receiver on. there may be electrical interference problems. This kind of interference is usually caused by electric
motors, neon lights, lighting equipment, appliances and other types of electrical equipment Electrical interference will
generally affect all wireless systems at a location, not just one system.
- Certain types of buzzing sounds are actually due to interference from TV stations. if the buzzmg sound changes
substantially at more or less random intervals and does not seem to be caused by electrical equipment, the problem may
be TV interference.
. Interference that takes the form of bursts of static or short bursts of noise is likely to be caused by lightning, intermittent
arcing or defective electrical machinery. This type of random interference is pretty rare but can be among the most
difficult to resolve.
If none of the descriptions match your particular problem, or the information is unclear. see the “Types of interference
section" below. Your authorized dealer may also be able to offer assistance and might be familiar With any unusual local
conditions that could be affecting the problem. If your dealer is not able to assist, owners of VocoPro equipment can obtain
telephone support at 800-678-5348 9A-5P M-F Pacific Time.
Avoiding Basic Problems
Sometimes interference problems have very basic causes. To avoid wasting lime on an easily correctable problem, check
the following items before proceeding:
- Make certain than no radio transmitters are allowed to come closer than approximately 10 to 15 feet of the wireless
receiver antennas. This can overload the receiver and increase the chances of interference
- Make certain not to allow receiver antennas to touch each other when arranging them. Be sure that the antennas from
one receiver do not touch. or come too close to, those of another receiver. Try to provide at least 10 inches of separation
between the antennas of any two receivers
' Make sure that all microphones have charged batteries. The low output voltage of weak batteries can cause some
microphones to generate harmful interference. If there is any doubt. install fresh batteries in all microphones.
~ Make sure that the wireless frequencies are not on a local TV channel.
- Check the wireless frequencies in use to make sure that no two systems are on the same frequency.
- Check to make sure that no two wireless frequencies are too close together. in general, 1 MHz is the recommended
minimum spacing between systems.
~ lf a considerable number of systems will be used. operating conditions will be difficult or interference is likely, if possible
avoid these situations.
- Before using a system in a new location or another city, double~check for new problems. Small changes in conditions can
cause interterence Where none was present before.
- Turn off unnecessary electronic equipment. especially computers and digital devices. These are a relatively common
cause of wireless interference.
- If use of computers or digital devices is necessary. keep them at least 18 inches (45 cm) away from the microphones and
receiver antennas.
Tips for Acheiving Optimal Performance
Frequency Conflicts
There are two primary ways that other VHF wireless systems and TV channels cause interference, The first is a direct
frequency conflict. If two VHF Wireless systems are on the same frequency. usually neither system will be usable unless
the other is turned off, This problem is more common than Might be expected. especially when all the equipment is the
same type This is because most systems have only a limited number of standard frequencies It should be remembered
that the other systems could be some distance away — in another house of worship down the street. in another nearby
studio. or at another club in the vicinity.
TV transmitters can also be a powerful source of direct interference if the wireless frequency falls within the assigned
channel of a local TV station. This problem sometimes occurs because wireless frequencies are listed in MHZ and it is not
always obvious Within which TV channel a particular frequency falls. For reference, below is TV frequency information.
TV Channel Frequency Data
VHF TV Channels
Channel
Number Frequency Range(MHz) Picture Carrier Frequency (MHz) ColorSubcarrier Frequency (MHz) Sound
Subcarrier Frequency (MHz)
7 174-100 175.250 178.8295 179.750
8 180486 181250 184.8295 185.750
9 1&6»192 187.250 190.8295 191.750
10 192498 193.250 196.8295 197.750
11 198404 199 250 202.8295 203 750
12 204-210 205 250 208.8295 209.750
13 210»216 211250 2148295 215.750
NOTE: The low VHF TV channels (2 through Glare not used for wireless microphones and do not need to be
considered
13
14
Troubleshooting
No sound output, RF LED not
glowing
Received signal is noisy or
contains extraneous sounds with
the mlcrophone(s) ON
Noise coming from the receiver
with the microphones turned OFF
Momentary loss of sound as
microphone(s) are moved
throughout the operating range.
-Make sure the microphone and receiver power switches and receiver are set to the
ON position.
-Check microphone batteries to ensure that they are providing sufficient power.
Replace battery if necessary.
-Check receiver’s AC power connection
Make sure antennas are firmly connected and extended to an optimal position.
-If necessary, reduce the distance between the microphones and receiver.
-Turn up the receiver’s VOLUME level controls.
-Check for proper connection between receiver and external amplifier/mixer.
-Talk into the microphone and observe the receiver's RF signal LED's. if they glow,
the problem is elsewhere in the sound system.
-Check microphone(s) batteries and replace if charge is low.
-Remove local sources of RF interference, such as lighting equipment.
-Signal may be too weak. If so, reposition antennas. (If possible, move them closer
to the transmitter).
-Adjust the squelch application to the microphone channels in use.
-Remove local sources of RF interference, such as lighting equipment.
AReposition the receiver or antennas.
Reposition the receiver and perform a “walkthrough” and observe the signal
strengths. If audio dropouts persist, mark these “dead spots" in the operating area
and avoid them during the performance.
Specifications
TECHNICAL DATA
RF Carrier Frequency Range: VHF 174;2~215.8MH2
Total Harmonic Distortion: < 0.7% (+15 kHz deviation, 1 kHz modulation)
Frequency Response: 50 Hz~15, i- 2dB
Audio Output Level: t 15 kHz deviation, 1 kHz tone, (1/ " connector into 3k load): -8.8 dBV (Hi-Z)
Temperature Range: -10~50* C
Sensitivity Range: Approximately 300-fl (100m) under typical conditions
Power Supply: Receiver: AC 120V/50 Hz, Mics: 2 x 1.5V alkaline batteries
Power Consumption: 18-24V
Current Drain:Transmlttor: 35mA average (40mA max), Receiver: 180mA average (200mA max)
Operating Temperature Range: —4 to 122 degrees Fahrenheit. Battery dimensions may limit this range.
15

---

Source Exif Data:

File Type                       : PDF
File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.5
Linearized                      : No
Page Count                      : 2
Has XFA                         : No
XMP Toolkit                     : XMP toolkit 2.9.1-13, framework 1.6
About                           : uuid:b53a316b-e1e0-403e-ba40-a2dd18b71180
Modify Date                     : 2009:02:11 13:21:54+01:00
Create Date                     : 2009:02:11 13:21:44+01:00
Metadata Date                   : 2009:02:11 13:21:54+01:00
Document ID                     : uuid:f757ff08-732c-4d77-9063-0f46a32d1efb
Format                          : application/pdf
Title                           : VHF-4808˵Ã÷Êé.cdr
Creator                         : CorelDRAW Version 9.397
Author                          : ΢ÈíÓû§
Producer                        : Corel PDF Engine Version 9.397

EXIF Metadata provided by EXIF.tools