Field Notes
Straight answers about wireless frequencies for people who have to make them work on a schedule. What you may legally transmit on, what the 600 MHz auction took away, how to coordinate a bag that does not fall over, and what changes the moment you leave the country.
Every regulatory claim here is sourced to the rule text it comes from. Where a question could not be answered from a primary source, the note says so instead of guessing.
Rules & licensing
- What frequencies can wireless microphones legally use in the US?The complete list of legal US wireless microphone frequencies in 2026, split by licensed Part 74 and unlicensed Part 15 operation, with exact MHz boundaries.4 min read
- The 600 MHz repack, explainedWhat the FCC Broadcast Incentive Auction did to wireless microphones, why 617–698 MHz went dark on July 13 2020, and exactly what spectrum survived near 600 MHz.4 min read
- Why TV channel 37 is off limits608–614 MHz is prohibited for wireless mics under both Part 74 and Part 15 — the rule, the radio astronomy history, and the hospital telemetry service sharing it.4 min read
- Do you need an FCC license for wireless microphones?Who qualifies for a Part 74 wireless mic licence, what it actually gets you, the 50-device certification for sound companies, and how to file Form 601 in ULS.5 min read
- WMAS, explained: the new wideband wireless standardThe FCC authorised Wireless Multichannel Audio Systems in 2024. What WMAS is, the bandwidth limits, the 3-channels-per-MHz rule, and whether it matters to you yet.5 min read
- Registering in the white space databaseWhat TV white space database registration does for wireless microphones, who is allowed to register, which administrators are listed, and whether it is worth your time.4 min read
Planning a shoot
- Why your wireless drops out near a TV towerA strong TV transmitter can shut down a receiver tuned nowhere near its channel. How front-end overload differs from co-channel interference, and what fixes it.5 min read
- How to coordinate frequencies for a multi-channel bagA working order of operations for coordinating 4, 8 or 16 channels of wireless: pick a block, scan, space the carriers, check intermod, walk it, write it down.5 min read
- Intermodulation, explained without the mathWhat intermod products are, why third-order products are the ones that bite, and why the problem gets out of hand so fast as you add transmitters to a bag.5 min read
- Scanning and walk-testing on locationHow to run a scan that tells the truth: all transmitters off, at the real antenna position, at the real time — then walk the whole set and re-scan once the crew arrives.5 min read
- Troubleshooting dropouts and hits on setA diagnostic order for wireless problems on location: separate RF from audio first, then work antennas, batteries, body, diversity and multipath before changing frequencies.5 min read
- Choosing blocks when you work in more than one marketHow to pick wireless block coverage that survives Los Angeles, New York, Chicago and Atlanta, why a single block is a trap, and when wideband tuning pays for itself.4 min read
Gear & blocks
- Lectrosonics blocks: what each one coversEvery Lectrosonics block with its exact MHz range, plus which ones still fit inside legal US spectrum and which ones now sit in carrier territory.4 min read
- Shure wireless bands: G, H, J, K, L and X explainedEvery Shure frequency band with its exact MHz range and US legal status, across the Axient Digital, ULX-D, QLX-D, SLX-D and PSM families.5 min read
- Sennheiser ranges: A, B, G, Q, R and the EW-DX eraEvery Sennheiser frequency range with its exact MHz span and US legal status, from EW-DX and EW-D to Digital 6000, Digital 9000 and the legacy evolution bands.4 min read
- Working above 700 MHz: 900 MHz, 1.9 GHz and 2.4 GHzWhen to reach for 902-928 MHz, 1920-1930 MHz or 2.4 GHz wireless instead of the UHF TV band, what those bands are shared with, and what you give up.4 min read
Working abroad
- Wireless microphone frequencies in CanadaCanada licenses wireless microphones under ISED RSS-123. The bands, eligibility tiers, the CPC-2-1-11 procedure, and why US UHF gear may not tune them.5 min read
- Wireless microphone frequencies in the UKOfcom licenses UK wireless mics directly. Licence-exempt bands, licensed VHF and UHF, Channel 38, current PMSE fees, and what a US licence buys.4 min read
- Wireless microphone frequencies in MexicoWhat is actually confirmed about wireless mic frequencies in Mexico: IFT free-use bands, the gaps in the published record, and why an FCC ID is not homologación.5 min read
Reference
- RF glossary for production soundPlain-English definitions of the RF terms that come up in wireless microphone work — from block and duplex gap to intermod, HAAT, ERP and white space.5 min read
- How RF Scout scores a locationThe method behind RF Scout's Recommended, Caution and Avoid labels — type weight, distance falloff, frequency overlap, and what the score cannot see.3 min read
Stop reading, start scoring
All of this is background. The useful version is the one that knows where you are standing — enter a shoot location and RF Scout scores every channel against the stations actually near it.
Score your location