wireless systems to operate in close proximity without degradation

in performance due to the presence of other wireless systems

and TV stations in the area.  Wireless microphone systems are

simply mini FM radio stations and are subject to the same laws of physics.

UHF wireless microphone systems operate in the RF spectrum

occupied by television stations and pre-planning is imperative

as to not operate on or close to those operating frequencies used

by local broadcasters. Analog TV stations operate on 6 MHz wide

channels with three transmission frequencies: video, color and audio.

DTV stations operate on a 6 MHz wide span also but occupy the

entire 6 MHz therefore you cannot space between carriers

like you can with analog stations.      

Major manufactures of wireless microphone and personal

monitoring systems have done a good job in assuring

their systems work together without IMD interference.

Potential problems lie in channel spacing from company to company.

Manufacturer imbedded scanning systems work well because

they integrate with pre-selelcted RF’s that will be intermod free.

For example, when you set up a Shure system using the

pre selected channels and integrate Sennheiser or Audio Technica

with their frequency sets you will most always have IMD products

that will interfere with the fundamental operating frequency

of another channel potentially causing interference problems.

Not only do you have to coordinate wireless microphone systems

to one another you have to coordinate with the carrier frequencies

of local TV stations.  Even if you use scanner and spectrum analyzers

you will still need to “crunch the numbers” and find operating

frequencies that will not interfere with one another.

JCS Pro Audio uses a program developed by Professional Wireless

to coordinate large numbers of wireless systems to operate

without interference. During a show in Lowell MA more than 43 channels

were in operation at one time without interference.  Spreadsheets were
generated from information gathered several weeks prior

on the systems performers were carrying.  These included

IEM, handhelds, head worn and com from different manufactures.

It was a challenge because multiple performers with the same

frequency groups or ranges were scheduled to play around the

same time so we had to make everything work together without issues.

The systems were from Shure, Sennheiser, AT and Telex.

Lectrosonics ENG sets were being used by a local broadcaster

at the show along with video RF transmission from stage cameras.

As usual there were many systems not reported in the original tally

so “on the fly” coordination was accomplished with great success.

This same procedure can be performed for touring companies

who do not have the time or expertise on staff.

If you have a need for wireless frequency coordination

please contact us. We are here to help you put on the

best show possible with the least amount of “interference”.

We also provide services for multiple unit

and multiple manufacture installs. 

With the abundance of frequencies crowding the airwaves

(and it will only get worse)  it is imperative to pre-plan

a system for the best show possible and rule out the probability

that it will be “stepped on”. Here are relevant documents

from the FCC (97-245,  01-364,  04-113,), DTV Final Assignment
James Stoffo comments on 04-113,  Sennheiser paper on white noise

Call JCS Pro Audio for more information.