Frequencies
Every wireless microphone system must operate on a specific frequency.

The government dictates which frequency ranges can be used by wireless.

By government policy, all frequencies are shared by a large number of users across the country.

Wireless frequencies are shared with TV stations, communications equipment and a large number of wireless microphone systems.

Because of frequency sharing, there is always at least a small chance that someone else in the area might be using the same frequency as your wireless system.

Government regulations also set strict technical requirements for wireless, including limits on maximum transmitter power.

Transmitter and Receiver
There must be one transmitter and one receiver to make a complete wireless system, and they both must be on the same frequency.

If any two transmitters are operating on the same frequency, severe interference will result and the wireless system will be unusable. Two transmitters cannot be used with one receiver at the same time. You can "use" a handheld and a body-pack transmitter with one receiver - one at a time!

If the frequencies of any two wireless systems are too close together, interference is likely, and one or both systems will probably be unusable.

The practical maximum operating range of a wireless system will vary from as little as 100 feet (30 m) in heavily crowded indoor situations to approximately 1,000 feet (300 m) under open outdoor conditions.

Diversity wireless systems will almost always have better operating range than similar non-diversity systems.

Common Problems
Wireless receivers must have either one or two external antennas, and there should be a clear open-air path between these antennas and the transmitter.

Weak or worn-out transmitter batteries are a common cause of wireless problems, including complete failure, poor range, distorted audio and interference.

High-quality alkaline batteries will provide 8 to 16 hours of transmitter operation. Most other types of batteries will have much shorter life, and some may cause other problems.

Feedback
Because it is easier to accidentally walk near speakers, feedback problems are slightly more common with wireless microphones than with wired microphones.

The power output of wireless microphone transmitters is very low, only about 10% of that of a typical cellular phone, and they are completely safe to use. However, any source of RF energy may interfere with the normal functioning of implanted cardiac pacemakers or AICD devices. A body-pack transmitter should not be worn where it is immediately adjacent to such a medical device. Note also that any medical-device disruption will cease when the RF transmitting source is turned off.