Comments on FCC RM-11708 Symbol Rate Petition

Submitted by Dave Struebel WB2FTX

Radio Relay International has submitted comments to the FCC on RM-11708 which is the proposal to eliminate the 300  baud symbol rate limit on digital signals.   This baud rate limitation was set by the FCC in the early days of amateur radio digital use and is the only such baud rate restriction in the entire world.  This restriction applied when digital signaling only consisted of the use of two different audio tones (for audio  frequency  shift keying , AFSK) or a slight difference in the frequency of the transmitted signal,( frequency shift keying, FSK.) Since then amateur radio and commercial digital use has progressed and developed ways to increase the rate of  which characters can be sent while still only occupying the bandwidth of a typical HF SSB transmission.  This has been accomplished using combinations of multiple tones, phase changes and others.

RRI’s interest in this is that the archaic 300 baud limit restricts its Digital Traffic Network (DTN) and other US amateur users from using the Pactor 4 modulation technique which has basically doubled the sending rate of information on HF signals while still holding to the bandwidth of a SSB signal.  The American Radio Relay League has also proposed this elimination of the 300 baud symbol rate again because it artificially restricts the continued and further development of techniques allowing faster sending and receiving of digital signals in amateur radio, again with the United States being the only country in the world having such a restriction. Pactor 4 has been used by US amateurs operating as part of MARS or SHARES as well as the rest of the global amateur radio community.

A copy of RRI’s submitted is linked here for your review.

73 Dave WB2FTX

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