Earlier this month, the ARRL filed a Petition for Rulemaking and a Request for Temporary Waiver with the FCC, seeking authorization of the use of single-time-slot Time Division Multiple Access (TDMA) emissions in the amateur bands at and above 50 MHz, wherever multiple-time-slot TDMA is authorized. The FCC has designated the Petition as RM-11625 and is soliciting comments on it. Comments may be filed electronically and will be accepted until April 22.

Through this rulemaking, the ARRL seeks to facilitate the use of and experimentation by radio amateurs with existing narrowband spectrum-efficient digital voice and data technology. “Such technology is now in regular and increasing use in the private land mobile radio services, but its use in the Amateur Radio Service is now apparently unintentionally precluded by two specific Commission rules,” the ARRL’s Petition stated. The Petition asks the FCC to allow those amateurs who are presently using a Motorola narrowband (12.5 kHz) digital land mobile system -- commercially marketed as MotoTRBO -- to be used legally. Because of some restrictions in the Part 97 rules, the TDMA repeaters (which are multiple-time-slot devices) are legal, but the mobiles and portables are not because the emissions used (single-time-slot TDMA) are not authorized anywhere, due to the emission designator.