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Understanding and Avoiding VHF Interference
Frequency Conflicts
There are two primary ways that other wireless systems and TV channels cause interference. The first is a
direct frequency conflict. If two 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.
Channel
Frequency
Number
Range (MHz)
7
174-180
8
180-186
9
186-192
10
192-198
11
198-204
12
204-210
13
210-216
NOTE:
The low VHF TV channels (2 through 6) are not used for wireless microphones and do not need
to be considered
TV Channel Frequency Data
VHF TV Channels
Picture Carrier
Frequency (MHz)
175.250
181.250
187.250
193.250
199.250
205.250
211.250
Color Sub carrier
Frequency (MHz)
178.8295
184.8295
190.8295
196.8295
202.8295
208.8295
214.8295
Sound Sub carrier
Frequency (MHz)
179.750
185.750
191.750
197.750
203.750
209.750
215.750
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