Unlicensed Fans Urge Caution on New Mic Tech

Shure and Sennheiser back an FCC proposal to allow wireless multichannel audio systems (WMAS) for wireless mics, in comments posted Tuesday in docket 21-115. Others urged caution; comments were due Monday on an NPRM OK’d 4-0 in April (see 2104220056). "Users have been burdened by significant reductions in available spectrum as a result of the Commission’s repurposing and repacking of TV band spectrum while the demand for wireless microphone support for a wide range of productions and events has only increased,” Shure said. “WMAS has the potential to enable wireless microphone users to pack far more wireless microphones into the same amount of spectrum and achieve the same high quality performance with no adverse interference impact to adjacent band and co-channel users.” OK WMAS for Part 74 licensed and Part 15 unlicensed, the company said. WMAS “allows the wireless microphone operator to maximize the available spectral resources,” Sennheiser commented: It "utilizes the spectral resources only" when needed. Remove the 6875-6900 and 7100-7125 MHz bands from the list of eligible frequencies for wireless mics, Microsoft said: “These bands have been unused by wireless microphones for years.” Microsoft urged a channel bandwidth limit of 6 MHz, a spectral efficiency of three mics per MHz for high-performance devices and power limits consistent with Part 74 rules. Cisco and Facebook asked that 6 GHz and 7 GHz mics be excluded, citing interference risks. “Steer clear of spectrum policy decisions that unnecessarily promote uncertainty impacting the future use of unlicensed technology that the Commission is so clearly relying on as a key ingredient in its recipe to advance the nation’s broadband goals,” they said. The Aerospace and Flight Test Radio Coordinating Council said it doesn’t have concerns on WMAS using the 1.4 GHz aeronautical mobile telemetry band, on a secondary basis, provided protections remain.