The deadline is Monday, December 23, to file comments on the ARRL’s “Symbol Rate” Petition for Rule Making (PRM). The ARRL filed the Petition last month, and the FCC has put it on public notice for comment as RM-11708. The League subsequently filed an Erratum to correct an incorrect appendix included within the Petition. The Petition already has attracted more than 70 comments.

The ARRL has asked the FCC to delete the symbol rate limit in §97.307(f) of its Amateur Service rules and to replace it with a maximum data emission bandwidth of 2.8 kHz on frequencies below 29.7 MHz. The ARRL contends that the changes it proposes would “relieve the Amateur Service of outdated, 1980s-era restrictions that presently hamper or preclude Amateur Radio experimentation with modern high frequency (HF) and other data transmission protocols” and “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. The League’s petition points out that other radio services use transmission protocols in which the symbol rate exceeds the present limitations set forth in §97.307(f), while staying within the bandwidth of a typical HF single sideband channel (3 kHz).

“The symbol rate restrictions were created to suit digital modes that are no longer in favor,” the ARRL noted in its petition. “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.”