ARRL Files Petition for Rulemaking with FCC to Create New MF Band at 472-479 kHz


At the 2012 World Radiocommunication Conference (WRC-12), delegates approved Agenda Item 1.23: a 7-kilohertz-wide secondary allocation between 472-479 kHz for the Amateur Radio Service, with a power limit of 5 W EIRP (or 1 W EIRP, depending on location). Before this portion of spectrum is made available to radio amateurs in the US, the FCC must first approve its use and amend its rules to reflect the change. As such, the ARRL filed a Petition for Rulemaking on November 29, asking the FCC to amend Sections 2 and 97 of its rules and create a domestic Amateur Radio allocation at 472-479 kHz, conforming to the allocation status and limitations set forth in the international Radio Regulations.

“The subject of a low-frequency (LF) allocation, and/or a medium-frequency (MF) allocation in the lower portion of that range for the Amateur Radio Service has a long history at the Commission,” the ARRL pointed out in its Petition. “As yet, however, the Commission has not created either one.” Presently, the lowest domestic frequency allocation for the Amateur Service -- and the only MF allocation -- is at 1800-2000 kHz.

The ARRL also pointed out that there is an Amateur Radio allocation in all other areas of the radio spectrum, providing for experimentation in virtually all types of radio frequency communications. “Technical self-training and furtherance of radiocommunications development in the Amateur Service (which is in essence an experimental radio service) would be greatly enhanced by an LF allocation and an allocation in the lower portion of the medium-frequency (MF) range,” the ARRL maintained. “It is now timely, in response to actions taken at the 2012 World Radiocommunication Conference (WRC) to create a new, domestic MF allocation at 472-479 kHz for the Amateur Radio Service.” The ARRL pointed out that while it is also desirable and timely to have an allocation in the LF portion of the spectrum, that matter was addressed in the Notice of Proposed Rulemaking and Order, just released in ET Docket 12-338 on November 20.


The issue of a domestic LF and/or low MF allocation for the Amateur Radio Service first formally arose in connection with the FCC’s preparation for the 1979 World Administrative Radio Conference (WARC-79). To prepare for that WARC, the FCC issued a series of Notices of Inquiry in Docket 20271. It used the comments received in response to these as the basis for the United States’ WARC-79 proposal. Prior to that docket proceeding, the Commission had established an Advisory Committee for Amateur Radio, relative to WARC-79 preparations. The Advisory Committee stated, in a report issued May 18, 1976 at Page 50, as follows:

There exists among some amateurs a keen desire to conduct experimentation and communication at low frequencies, as well as at vhf and uhf (sic). The FCC authorizes the operation of low power communication devices in the band 160-190 kHz under Part 15, Subpart D, of its rules. Despite the severe restrictions of one watt power input and a total length not to exceed 15 meters, experimenters have been successful in transmitting over paths of several hundred miles under favorable conditions. An amateur allocation with less severe restrictions in this band, which is now allocated to the fixed service in Region II but is little used outside of Alaska, would permit amateurs to resume experimentation in a portion of the spectrum which has not been available to them for more than 50 years.

Notwithstanding this recommendation and the filing of extensive comments by the ARRL, a Report and Order terminating released in December 1978 concluded that the 160-190 kHz band could not be made available to the Amateur Radio Service due to concerns of interference to power line carrier (PLC) systems.

In October 1998, the ARRL filed a Petition for Rulemaking, seeking LF allocations for the Amateur Radio Service at 135.7-137.8 kHz and 160-190 kHz. The Petition noted, with respect to the 135.7-137.8 kHz band, that radio amateurs in other countries had already been accommodated in that segment, including Belgium, Finland, Norway and the United Kingdom. Other countries at the time permitted Amateur Radio experimentation at LF via special or experimental authority, including Germany, Iceland, Italy, Luxembourg and Australia. Allocations were pending at the time in France and Sweden. A 1997 CEPT recommendation was the basis for the specific interest in the band 135.7-137.8 kHz in Europe. The justification for the proposed allocation of 160-190 kHz in the ARRL’s Petition was the fact that numerous radio amateurs and experimenters were already using that band pursuant to Part 15 rules, which allows operation in that band at up to 1 W input power, but with significant antenna size restrictions that severely restricted antenna efficiency and compromising most experimentation in that band.

The FCC issued a Notice of Proposed Rulemaking in May of 2002 in response to the ARRL’s Petition. The FCC also specifically found that “…this allocation appeared to be acceptable because the incumbent use of the 135.7-137.8 kHz band appeared to be very light, and thus a secondary Amateur Service allocation in this band would likely raise few interference concerns.” It was also noted that the use of LF frequencies generally by unlicensed devices was on an “unprotected, non-interference basis” and that PLC systems are permitted pursuant to Section 15.113 of the FCC’s rules to operate in the 9-490 kHz segment. Because of concerns related to potential interaction between PLC systems and amateur stations, the FCC did not propose to allocate the 160-190 kHz band to the Amateur Radio Service, and ultimately, in May 2003, the FCC declined to create the secondary allocation proposed by ARRL in either LF band, citing what the ARRL called in its 2012 Petition “generalized but technically unsubstantiated concerns in comments filed by the United Telecom Council (UTC) and by an IEEE committee about potential interference to PLC facilities.” Those issues are also to be revisited in ET Docket 12-338.

472-479 kHz and WRC-12

The ARRL pointed out in its current Petition for Rulemaking that “[n]one of the Commission’s past concerns with Amateur Radio interaction with PLC systems operating at 160-190 kHz or 135.7-137.8 kHz -- however valid those concerns might have been at the time -- applies or has applied to the band 450-490 kHz.” An international allocation to the Amateur Radio Service at 472-479 kHz was adopted at WRC-12 with of 5 W EIRP for most of the world. The Final Acts of WRC-12 become effective on January 1, 2013.

“The allocation was made in fulfillment of WRC-12 Agenda Item 1.23, considering a secondary allocation to the Amateur Radio Service in the range 415-526.5 kHz,” the ARRL stated. “Studies conducted in support of the Agenda Item considered present and future uses by incumbent services (mobile, including maritime mobile and aeronautical radiolocation). Several frequency ranges for the allocation were considered. Ultimately, WRC-12 concluded that the range 472-479 kHz offered maximum protection to existing and future applications in these services, consisting primarily of broadcast data transmissions in the maritime mobile service and aeronautical non-directional beacons in the aeronautical radiolocation service. Several administrations -- including Germany, Sweden, the Netherlands, New Zealand and Monaco -- have already authorized Amateur Radio Service operation on the 472-479 kHz band beginning on or in advance of the January 1, 2013 implementation date of the WRC-12 Final Acts.”

In the United States, the 472-479 kHz band is part of the larger segment 435-495 kHz that is allocated on a primary basis to the Maritime Mobile Service (federal and non-federal users), and on a secondary basis for federal government aeronautical radionavigation. The ARRL stated in its Petition that it is not aware of any domestic assignments that would conflict with the allocation of the band 472-479 kHz to the Amateur Radio Service, and there is almost no PLC operation in this band segment.

According to a 2002 article in IEEE Transactions on Power Delivery entitled “Evaluation of the Potential for Power Line Carrier (PLC) to Interfere With Use of the Nationwide Differential GPS Network” (Silva, Michael, Senior Member, IEEE and Whitney, Bruce, Member, IEEE), of the 28,816 PLC transmitters that existed in the United States in 1999, only 20 operated anywhere in the band 450-490 kHz. Of the 40 kilohertz-wide segment referred to in the article, only 7 kilohertz is proposed to be allocated to the Amateur Radio Service in the US.

“Therefore, even if any of those 20 PLC transmitters that operated somewhere in the 450-490 kHz in 1999 are still operational,” the ARRL said, “and even if any of those which were operating in 1999 and which are still operational are presently operating in the small segment 472-479 kHz, it would surely be a simple matter indeed to retune those very few PLC transmitters less than 4 kilohertz, which is less than 1 percent of the available operating frequencies for PLC systems at LF and MF. So, very little adjustment would be required, if any would be called for at all, and it would be a simple matter indeed to do so.”

The ARRL maintained that the 5 W EIRP maximum power specification recommended at WRC-12 for this band will not affect the utility of the allocation for radio amateurs: “Given typical antenna efficiencies in this frequency range, Amateur Radio stations operating in this band are likely to fall well within this limit. International footnote 5.80A (Geneva 2012) would impose a 1 W EIRP limit on US radio amateurs only when operating within close proximity to certain countries, including the Russian Federation. As a practical matter, only stations in the western part of Alaska, or certain maritime mobile amateur stations, could be affected by this limit.”

As such, the ARRL, in its Petition, proposes to implement these power limits. “The utilization of narrow bandwidth emissions has proved satisfactory in extensive experimental operation in the vicinity of 500 kHz in the United States,” it said.With respect to this band, no reports of harmful interference to the primary services (or to PLC systems) from experimental amateur operation have been received. Any likelihood of interaction between amateur stations and PLC systems in this band will be exceptionally low.”

The ARRL has sponsored an extensive course of experimentation in the MF spectrum near 500 kHz since 2006. In September 2006, a group of 23 amateur stations -- using call sign WD2XSH -- scattered throughout the US were permitted to operate in the band 505-510 kHz for a course of experimentation with propagation and interference testing. During the course of this experiment, the number of participating amateur stations increased to 42, and includes all geographic areas of the US, including Alaska and Hawaii. The frequency bands utilized were modified to include the entirety of 461-478 kHz and 495-510 kHz. Emissions, at power levels up to 20 W ERP, include 150 HA1A, 62H0J2B, 62H0F1B and 62H0G1D. This experiment is scheduled to continue through the end of the current license term, August 1, 2015. No reports of interference have been received. This is a disciplined program of experimentation with regular reports and analyses of interference potential to other services (including PLC systems) and experimentation with equipment and antennas.

Should, for any reason, PLC systems deem it necessary to continue to utilize this small segment going forward, and to the extent shown to be necessary, the ARRL stated in its Petition that it would be willing to maintain a database of Amateur LF operation at 472-479 kHz and to provide it to the FCC in accordance with the spirit and intent of Footnote US2, the NTIA Manual and the Commission’s Part 90 rules; however, the ARRL pointed out that Footnote US2 makes it clear “that PLC systems operating in this band are unprotected, and it would be difficult to imagine why any PLC system would need to continue to operate in this small segment in this area of the spectrum on an ongoing basis. Finally, it is noteworthy that PLC systems are used on transmission systems only, and not on distribution systems. It is unlikely therefore that any will be in close proximity to Amateur stations. PLC systems are obligated by the FCC’s rules to ‘adhere to industry approved standards designed to enhance the use of power line carrier systems.’ This is intended to facilitate additional overlay uses of the same LF or MF spectrum.”

The ARRL said that PLC systems are, or can be capable, of this through the “frequency agility of PLC transmitters (either using software-defined radio equipment or by simply notching small segments of the 9-490 kHz band available to them), and more especially by PLC system design in compliance with the immunity standard IEEE-1613. That standard sets a high bar for immunity of PLC systems, and if met, would virtually guarantee that there would be no interaction between amateur stations and PLC systems in this range, even of the latter were operated on a co-channel basis. Compliance with this standard is called for by Section 15.113 of the Commission’s rules, and PLC devices sold to utilities and placed within substations since 2002 have been subject to this standard.” Also, systems operating pursuant to certain standards utilize polite protocols “which will delay a PLC transmission if the channel on which the PLC system wishes to transmit senses that the channel is occupied. Given the above factors, and the very small number of PLC systems (if any) that might currently be operating in the narrow range 472-479 kHz, it is suggested that there will be virtually no interaction between the two uses.”

The ARRL, in its Petition, offered a proposed change to Section 97.305(c) to permit use of RTTY and data emissions in this new secondary allocation (please see the appendix, located on pages 14-15 of the Petition for Rulemaking); as per the existing Section 97.305(a), radio amateurs would also be permitted to utilize CW emissions in the band. The appendix also proposes to permit General and Amateur Extra Class licensees access to the band. Technician class licensees would not be permitted to utilize the band. The maximum permitted power level for this band proposed in the appendix would be either 1 or 5 W EIRP maximum power, consistent with the international allocation made at WRC-12.