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ARRL General Bulletin ARLB030 (2013)

ARLB030 ARRL Files "Symbol Rate" Petition with FCC

QST de W1AW  
ARRL Bulletin 30  ARLB030
From ARRL Headquarters  
Newington CT  November 20, 2013
To all radio amateurs 

ARLB030 ARRL Files "Symbol Rate" Petition with FCC

The ARRL has asked the FCC to delete the symbol rate limit in
§97.307(f) of its Amateur Service rules, replacing it with a maximum
bandwidth for data emissions of 2.8 kHz on amateur frequencies below
29.7 MHz. The ARRL Board of Directors adopted the policy underlying
the petition initiative at its July 2013 meeting. The petition was
filed November 15.

"The changes proposed would, in the aggregate, relieve the Amateur
Service of outdated, 1980s-era restrictions that presently hamper or
preclude Amateur Radio experimentation with modern high frequency
(HF) and other data transmission protocols," the League's petition
asserted. "The proposed rule changes would also permit greater
flexibility in the choice of data emissions." Symbol rate represents
the number of times per second that a change of state occurs, not to
be confused with data (or bit) rate.

Current FCC rules limit digital data emissions below 28 MHz to 300
baud, and between 28.0 and 28.3 MHz to 1200 baud. "Transmission
protocols are available and in active use in other radio services in
which the symbol rate exceeds the present limitations set forth in
§97.307(f) of the Commission's Rules, but the necessary bandwidths
of those protocols are within the bandwidth of a typical HF single
sideband channel (3 kHz)," the ARRL's petition pointed out.

The League said that while bandwidth limitations are reasonable, the
symbol rate "speed limit" reflective of 1980s technology, prohibits
radio amateurs today from utilizing state-of-the-art technology.
Present symbol rate limits on HF "actually encourage spectrum
inefficiency," the League argues, "in that they allow data
transmissions of unlimited bandwidth as long as the symbol rate is
sufficiently slow." The League said eliminating symbol rate limits
on data emissions and substituting a "reasonable maximum authorized
bandwidth" would permit hams to use all HF data-transmission
protocols now legal in the Amateur Service as well as other
currently available protocols that fall within the authorized
bandwidth but are off limits to amateurs.

The League said it's been more than three decades - when the
Commission okayed the use of ASCII on HF - since the FCC has
evaluated symbol rate restrictions on radio amateurs as a regulatory
matter. "The symbol rate restrictions were created to suit digital
modes that are no longer in favor," the ARRL noted in its petition.
Modern digital emissions "are capable of much more accurate and
reliable transmissions at greater speeds with much less bandwidth
than in 1980."

As an example, the League pointed to PACTOR 3, which is permitted
under current rules, and PACTOR 4, which is not. Despite PACTOR 4's
greater throughput, both protocols can operate within the bandwidth
of a typical SSB transmission.

"If the symbol rate is allowed to increase as technology develops
and the Amateur Service utilizes new data emission types, the
efficiency of amateur data communications will increase," the ARRL

ARRL General Counsel Chris Imlay, W3KD, has emphasized that there is
no broader plan on the League's part to seek regulation by

The FCC has not yet assigned an RM number and put the League's
petition on public notice for comments, and there is no way to file
comments until that happens.


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