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16

Understanding and Avoiding VHF Interference

Recognizing Interference

The ways of recognizing the type of interference present are observing the receiver LED indications and 
carefully listening to the audio. 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. 
  If 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 intermodulation, 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 time 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 buzzing 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.

Содержание DA-2277

Страница 1: ...ume Controls Digital Echo On Off Switch on 3 Mic Channels Music Bass Treble and Volume Controls Microphone Master Bass and Treble Controls Four A V Inputs and Two A V Outputs for Maximum System Integr...

Страница 2: ...l Descriptions Rear Panel Descriptions Microphone Descriptions Replacing Recharging the Microphone Batteries Getting Connected Understanding and Avoiding VHF Interference Troubleshooting Glossary of T...

Страница 3: ...r surface that may block the ventilation slots 9 Heat The appliance should be situated away from heat sources such as radiators heat registers stoves or other appliances including amplifiers that prod...

Страница 4: ...e unit first turn the unit off Then gently disconnect the power plug and the cords connecting to other equipment Never pull the cord itself 7 Do not attempt to clean the unit with chemical solvents th...

Страница 5: ......

Страница 6: ...dial and leave it there Pay attention to the different levels in various recordings Taking a minute to do this now will help to prevent hearing damage or loss in the future After all we want you liste...

Страница 7: ...ing Type TONE Squelch coding lock still sound design Receiving Sensitivity 10dB uV De emphasis 50uS Harmonic Interfering Ratio over 80dB DA 2277 FEATURES Wireless Receiver Base Charges Wireless Microp...

Страница 8: ...back of the DA 2277 instead of straight down the middle of the back of the DA 2277 Important Stand and Base Safety Information Choose the location for your DA 2277 carefully If the DA 2277 is placed...

Страница 9: ...transmitter batteries are a common cause of wireless problems including complete failure poor range distorted audio and interference Microphone Position The DA 2277 wireless microphones are ideal for...

Страница 10: ...th wireless understanding and being able to apply these techniques will be helpful Request that the talker speak louder into the microphone so microphone levels can be reduced Reduce the distance from...

Страница 11: ...s only 4 A V SOURCE button This button toggles input between devices that may be connected to the CDG and DVD A V channels For input from the CDG channel press the A V SOURCE button once For input fro...

Страница 12: ...turn clockwise to increase and counter clockwise to decrease 10 MIC 3 AND 4 jacks These 1 4 inch input jacks are for connecting microphones or instruments 11 REMOTE KEY CONTROL jack This jack is for c...

Страница 13: ...yers can be connected 6 VIDEO IN jacks RCA These jacks are for connecting VIDEO from your A V source players Connect an RCA patch cable from these jacks to the VIDEO OUT jacks on your A V source playe...

Страница 14: ...ON OFF 3 CHARGE LED indicator This LED lights up when the microphone is being charged 4 BATTERY compartment This is where you insert the microphone batteries 5 WINDSCREEN CAPSULE The WINDSCREEN houses...

Страница 15: ...n place At that time make sure the CHARGING LED indicator is illuminated When the microphone is fully recharged the CHARGING LED indicator will no longer be illuminated In case you need to end the rec...

Страница 16: ...n isolated MICROPHONE OUTPUT connection connect a 1 4 audio patch cable from the AUDIO IN or LINE IN jacks on your external device to the 4 MIC ONLY 56dBv jack on the DA 2277 www vocopro com LA VERNE...

Страница 17: ...ble 0 15 15 Bass 0 15 15 Echo 10 8 CUE KEY 6 4 2 0 0 10 BALANCE MIC 2 Gain 5 0 10 Treble 0 15 15 Bass 0 15 15 Echo 10 8 CUE KEY 6 4 2 0 0 10 BALANCE MIC 3 MIC 3 MIC 4 Gain 5 0 10 Treble 0 15 15 Bass 0...

Страница 18: ...rect 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 time to time digital interference mig...

Страница 19: ...e 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...

Страница 20: ...nsmitters 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 frequenc...

Страница 21: ...et to a minimum The A V cables are not connected properly The echo on off button for the microphone channels are set to off Reinsert the microphone into the recharging terminal and gently turn it till...

Страница 22: ...from standard non multiplex CD tracks To do this the unit compares the audio on the left and right channels and cancels out any signals that appear on both Most currently recorded CD s contain the vo...

Страница 23: ...s VCRs Laser disc Players etc are connected in a system at line level usually with shielded RCA type interconnects Line level is before power amplification In a system with separate pre amp and power...

Страница 24: ...ection during pitch changes Single Track Mode Frame Search W Jog Dial 4 Speed Fast Forward Rewind Shuttle Pitch Slider Pitch Bend and Jog Dial BPM Beat Per Minute Synchronization Cue Detect Function P...

Страница 25: ...fessional Power Amplifier 300W 300W RMS 600W 600W Max THD 0 05 Frequency Response 20HZ 20KHZ Signal to Noise 1 4 or XLR Inputs Input Ratio Less than 100DB Input Sensitivity 1 23V Dimension W x D x H 1...

Страница 26: ...Sold in Pair Design for Karaoke Studio or Singers Monitor Power Rating 180 Watts Peak 90 Watts RMS Metal Grill Impedance 8 OHM Sensitivity 92 DB Frequency Response 20HZ 20KHZ Dimensions H x W x D 19...

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