The biggest problem with FM is the potential for outside interference. Although 40 channels (narrow band) in the 72-76 MHz bandwidth have been set aside by the FCC for use in FM systems, outside interference may occur with nearby radio stations, pagers, police band, and construction walkie talkies. Sometimes devices ‘drift’ from their targeted frequencies and must be adjusted to correct for this. . However, newly developed 216MHz systems are now available that should alleviate this intereference problem.
This system is also not a secure system. If you can leave the room and still pick up the signal, this means others could pick it up, as well. If security is an issue (as in jury deliberations or in high-tech company business) an infrared system would be the system of choice (discussed in the next section).
Receivers are required for everyone. These receivers vary in quality with the manufacturer. Only purchase these systems from companies that will help you troubleshoot and that have a trial period and return policy.
If you purchase multiple systems at separate times, color code or number transmitter and receiver pairs. Remember, the pairs must be tuned into the same channel.
Finally, if multiple systems are being used in close proximity, there must be at least one free channel between the separate systems to prevent interference in adjacent rooms.
