ARRL Renews Request for FCC to Replace Symbol Rate with Bandwidth Limit
In ex parte comments filed on September 17 in WT Docket 16-239, ARRL renewed its request that the FCC delete symbol rate limits below 29.7 MHz for data transmissions in the Amateur Service rules. As it did in its initial filing, ARRL asked the FCC to couple the removal of the symbol rate limits with the adoption of a 2.8 kHz bandwidth limit. 
In response to ARRL’s 2013 ARRL Petition for Rulemaking (RM-11708), the FCC proposed deleting the symbol rate limits but declined to replace them with the 2.8 kHz bandwidth that ARRL wanted.
"This proceeding addresses an update to the Commission’s rules that is needed because a limitation in the rules unintentionally is inhibiting US amateurs from employing the latest improvements to some of the digital modes," ARRL said in its remarks. "Data signals commonly used for daily communications as well as in disaster situations have bandwidths in the range of 2.5 kHz and must co-exist with other modes that use bandwidths as narrow as 50 Hz."
ARRL said the 1980s-era symbol rate limits today inhibit the use of some efficient data modes. Repealing the symbol rate limit, ARRL contended, would "allow shortened transmission times for the same amount of data without increasing the bandwidth occupied by the signal. Other Amateurs would benefit by the resulting reduction in potential interference."
Other Issues
ARRL’s remarks also addressed issues raised by other parties. "Discussion by commenters in this proceeding delve into subjects well beyond its scope," ARRL said, noting that it had attempted to broker consensus among "some of the most active commenters" with an eye toward exploring possible areas of agreement for the FCC’s consideration. ARRL noted that the parties to the ARRL-arranged talks 
declined to forward to the FCC "joint recommendations on which conditional agreement had been reached."
One of those issues involves Automatically Controlled Digital Stations (ACDS). Commenters’ concerns focused on interference that could occur with a move away from symbol-rate criteria. ACDS with signals wider than 500 Hz below 29.7 MHz are confined to specific subbands. ARRL recommended that the FCC consider rules changes that would have all ACDS stations and digital stations with bandwidths greater than 500 Hz share identified subbands.
ARRL said if additional signals are added to the ACDS subbands, as recommended, that it would strongly support expanding the HF ACDS subbands. But, the League added, "changing the subband boundaries requires study and careful consideration of trade-offs, because any changes will affect multiple user interests." ARRL referred subband reformulation issues to its HF Band Planning Committee for study and recommendations.
Some commenters also raised the issue of obscure and encrypted messages. ARRL pointed out in its ex parte remarks that it remains opposed to encryption in the amateur bands, but disagreed "with commenters who argue that the digital modes being used by radio amateurs around the world are per se ‘obscured’ or ‘encrypted.’" Read more.