LMR radio manufacturers must continue to build subscriber radios that are capable of operating on 6.25 kHz channels—or equivalent—below 512 MHz, the FCC ruled last week in denying a waiver request from the International Municipal Signal Association (IMSA).

In an order released last Friday, the FCC ruled against the IMSA request for a waiver that would let manufacturers receive certification for equipment that operates only on 12.5 kHz channels while signaling that an eventual requirement that LMR systems operate on 6.25 kHz is still possible.

“We find that resuming the certification of PLMR equipment that is not capable of operating on 6.25 kilohertz channels or with equivalent efficiency would not serve the public interest,” the FCC order states. “Such an action would increase the embedded base of equipment that is not 6.25 kilohertz-capable, and such equipment would eventually have to be replaced as part of the migration to 6.25 kilohertz technology, thus delaying the transition.

“We conclude, therefore, that delaying the 6.25 kilohertz capability requirement again would be contrary to the intent of the commission in establishing the narrowbanding rules and would frustrate the purpose of the underlying rule.”

As part of rulings associated with a mandate to narrowband LMR operations to 12.5 kHz channels below 512 MHz, the FCC indicated its intention to have such systems migrate ultimately to 6.25 kHz channels or equivalent. However, the FCC has not established a firm date for this transition, including in last week's order.

FCC rules have prohibited certification of LMR equipment that was not capable of 6.25 kHz operation since Jan. 1, 2015, but a 2014 ruling decided that a 6.25 kHz mandate would not apply to equipment operating on public safety’s 700 MHz narrowband spectrum in 2014. In that case, the FCC left the decision to Regional Planning Committees (RPCs). IMSA cited this public-safety ruling in its waiver request, but the FCC ruling asserts that it is not a precedent.

“The Commission decided that the transition to 6.25 kilohertz technology for the 700 MHz Public Safety channels was best placed in the hands of the RPCs, which have superior knowledge of local spectrum requirements,” the order states. “No such consideration exists in the bands below 512 MHz, which, rather than being used by one class of users and administered regionally by a single RPC, are shared by multiple classes of users and coordinated by multiple entities.

“Similarly, anticipating the possible future conversion of the 700 MHz public-safety band to broadband, the Commission elected not to impede such a conversion by mandating 6.25 kilohertz technology in the band.”

While RPCs have the option of considering broadband uses of the 700 MHz public-safety narrowband spectrum, that is not the case for spectrum below 512 MHz, where the FCC “contemplates further narrowbanding,” according to the order.

Another argument made by IMSA was that the mandate to support 6.25 kHz operation result in higher equipment costs that certain segments of the market could not afford. But the FCC order indicates that no evidence was provided to support IMSA’s claim, citing—in part—a filing from the Government Wireless Technology & Communications Association (GWTCA).

“What we felt, by interviewing our members—whether they are DMR members or the NXDN members—they really haven’t seen any increase in prices since manufacturers started including either DMR or NXDN in their radios,” GWTCA President Chris Lougee said during an interview with IWCE’s Urgent Communications. “In fact, now some of them are getting less expensive as they develop digital-only radios or lesser radios that include digital technology.”