Frequency coordination is the process of assigning every wireless microphone a clear, compatible radio frequency so multiple systems run at the same time without interference.
Good coordination prevents two problems:
- Occupied spectrum from television stations and other mics
- Intermodulation that your own gear creates
Below, we cover the legal bands, the coordination workflow, and the tools you need.
What Is Wireless Microphone Frequency Coordination?
Frequency coordination means selecting a set of radio frequencies that work together without conflict. Each wireless microphone needs its own frequency, and each transmitter pairs to one dedicated receiver. Coordination uses predictive math to pick frequencies that stay clear of local signals and of the interference your transmitters produce together.
A single channel of wireless equals one transmitter plus one receiver. Ten channels means ten transmitters and ten receivers, each tuned to a different frequency. If two transmitters share a frequency, or two receivers tune to the same transmitter, you get interference or duplicated audio. Coordinating frequencies is not the same as tuning them randomly. Arbitrary frequencies invite conflict.
Why Does Frequency Coordination Matter?
Wireless systems are pass-fail. A microphone on an occupied or conflicting frequency drops out, picks up static, or goes silent during use. Coordination matters because the risk grows with every channel you add. One extra microphone nearly doubles the number of interference points the system can create.
The consequences play out live: a dead mic during a keynote, a dropout in the middle of a service, crosstalk on a broadcast feed. For theater, touring, and multi-act events with high channel counts, coordination becomes mandatory rather than optional.
What Frequencies Can Wireless Microphones Legally Use?
In the United States, most professional wireless microphones operate in the UHF television band below 608 MHz, plus a few narrow segments and several license-free bands.
The 600 MHz and 700 MHz bands are no longer legal for wireless microphone use. The 617–652 MHz and 663–698 MHz frequencies were repurposed for wireless carriers, and microphones were required to cease operation in that band no later than July 13, 2020.
The 700 MHz band (698–806 MHz) is prohibited and reserved for public safety communications.
Unlicensed use is permitted on the 902–928 MHz band, the 1920–1930 MHz band, and on portions of the 2.4 GHz and 5 GHz bands under set power levels.
Check your transmitter's frequency range against this list. Any system locked to the 600 or 700 MHz band needs to be replaced. You can confirm the exact range in the user manual or with the manufacturer.
Do You Need an FCC License?
Most microphone users operate license-free under the FCC's Part 15 rules. A Part 74 license is available to qualifying users. Entities eligible for Part 74 licenses include broadcast stations and networks, certain cable operators, motion picture and TV producers, and professional sound companies and venues that routinely use 50 or more wireless microphones. A license grants protected access to bands like the duplex gap.
Power limits apply to every microphone. Wireless microphones are limited to 50 milliwatts EIRP in the VHF-TV bands, 250 milliwatts conducted power in the UHF-TV band, and 20 milliwatts EIRP in the 600 MHz duplex gap.
How Do You Coordinate Wireless Microphone Frequencies?
Coordination follows a repeatable sequence. Inventory every device that transmits, scan the venue, calculate a compatible frequency set, deploy it, then verify on site. Small setups manage this with onboard receiver scanning. Larger channel counts move to dedicated coordination software.
- Inventory everything that transmits: mics, bodypacks, in-ear monitors, intercom, and IFB. Note the make, model, and frequency band of each.
- Scan the venue: walk the stage, wings, and front of house with a receiver scan or handheld scanner to find occupied frequencies and strong TV carriers.
- Run a coordination: use manufacturer group and channel presets for low channel counts, or software for high counts.
- Deploy and label: assign one frequency per channel, label every unit clearly, and keep a short list of alternate frequencies.
- Verify and stage a backup: confirm a clean spectrum and keep a wired podium mic or a spare on a known-good frequency.
To check which channels local broadcasters occupy in your area, use a tool a frequency finder tool before you build your plan. A wireless system kit with onboard scanning makes the on-site step faster.
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What Are Groups and Channels?
Manufacturers pre-calculate groups of compatible frequencies. Each group holds numbered channels set to spot frequencies that do not interfere with one another. All channels within a given group are designed to be compatible with each other. Selecting every microphone from the same group removes most of the math.
What Is Intermodulation and How Do You Avoid It?
Intermodulation happens when two or more transmitters mix inside non-linear circuits and create new, unwanted frequencies called IM products. These products can land on a working microphone or in-ear frequency and cause interference, even when every original frequency scanned clean.
Two wireless units create two third-order artifacts, but three units create nine, so adding one channel nearly doubles the complexity each time. To stay safe, most manufacturers recommend a minimum margin of 250 kHz between any third-order IM product and any tuned carrier frequency. Lower transmitter power and wider spacing both reduce IM strength.
This is why scanning alone is not enough.
Frequency coordination is predictive, while scanning is reactive: scanning shows what is in the area right now, and coordination predicts the interference your own systems will generate. You need both.
What Tools Do You Need For Coordination?
Small setups coordinate with onboard receiver scanning and manufacturer presets. Larger or multi-band rigs need coordination software plus radio hardware: a spectrum analyzer or scanner to read the spectrum, and antenna distribution to feed multiple receivers from shared antennas.
- Software: use free coordination programs that calculate compatible frequency set across multiple systems.
- Spectrum analyzer or scanner: reads the radio environment so you can spot occupied frequencies and strong carriers.
- Antenna distribution: splits clean antenna signal to several receivers and reduces front-end overload.
- Directional antennas and short coax: improve signal and cut noise. Keep cable runs short and gain sensible.
Set transmitter power to the lowest stable level. This extends rechargeable battery life and lowers intermodulation at the same time. AVGear stocks new and used antennas, wireless microphone accessories, test equipment and tools, and audio signal processing and routing gear.
Is Microphone Frequency the Same as Frequency Response?
The phrase microphone frequency means two different things. Frequency coordination is about radio frequencies and avoiding interference.
Frequency response is about sound. It describes which audio frequencies a microphone reproduces and how evenly across its frequency range. A flat frequency response reproduces low frequencies and high frequencies at even levels, and a dynamic microphone and a condenser microphone often show different response curves. That spec affects sound quality, not radio coordination. You will find it on the mic's data sheet, separate from anything covered here.
How Many Wireless Microphones Can You Run At Once?
It depends on the band, the quality of your gear, and the local RF environment.
Within a single open TV channel, traditional analog wireless tops out around eight channels. Higher-end and digital systems fit more into the same space because they have a smaller RF footprint.
Newer Wireless Multichannel Audio Systems (WMAS), which the FCC approved in February 2024, transmit many channels over a wide bandwidth and push channel counts higher for large productions.
Common Wireless Problems and Quick Fixes
Most live radio problems trace to occupied spectrum, intermodulation, or a weak antenna setup. A single microphone with dropouts usually needs a clean alternate frequency. Several microphones dropping at once point to a shared cause.
- One mic with persistent hits: move it to a clean alternate frequency and update the label.
- Multiple mics with hits: check for a bad antenna cable, an overloaded distribution amp, or a scenic piece blocking line of sight.
- One performer only: check cable dressing, belt-pack orientation, and capsule choice.
- 2.4 GHz dropouts when the room fills: phones and Wi-Fi crowd that band. Move to UHF for dense audiences.
- Always have a backup: stage a wired mic or a spare on a known-good frequency
Buy or Sell Wireless Microphone Gear With AVGear
AVGear sells tested, graded wireless microphone systems, receivers, transmitters, antennas, and coordination-friendly accessories, including new and used gear at prices below retail. Every system is tested for RF performance and audio quality before it is listed. Want to score an even better deal? Check out our live auctions, where you can bid on select gear and grab it for less.
Moving off a discontinued band or upgrading your channel count? AVGear also buys used gear through direct purchase, consignment, and auction.
Get a quote on the Sell Your Gear page, and our team will follow up with options.