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ARRL Files Comments with FCC Regarding Spread Spectrum Issues


In response to a 2006 ARRL Petition regarding spread spectrum issues, the FCC released a Notice of Proposed Rule Making (NPRM) on March 16 (WT Docket No 10-62), proposing to amend Part 97 to facilitate the use of spread spectrum communications technologies by eliminating the requirement that amateur stations use automatic power control (APC) to reduce transmitter power when the station transmits a spread spectrum (SS) emission and reducing the maximum transmitter power output when transmitting a SS emission. The ARRL filed comments on this matter on June 14, 2010.

In its comments, the ARRL requests that the FCC proceed with the following proposals in the NPRM:

  • To delete the APC requirement of Section 97.311(d) of the Commission’s rules.
  • To move the power limit for SS communications from Section 97.311 to 97.313(j) of the rules.
  • If the record developed in comments in response to the NPRM supports the proposed power reduction from 100 W PEP output power to 10 W, as proposed, then to implement that power reduction, subject to revisiting the matter at a later date if the reduction proves a substantial disincentive to expanded SS experimentation in the Amateur Service.

The ARRL’s 2006 Petition proposed the deletion of Section 97.311(d) of the Commission’s rules, save for the first sentence thereof. “The effect of this would be to eliminate an automatic power control provision for Amateur Radio SS communications,” the ARRL stated in its comments. “The NPRM proposes that relief, but at the same time, as something of a tradeoff, proposes to reduce the maximum transmitter power output when an amateur station is transmitting an SS emission, from a maximum of 100 W to a maximum of 10 W PEP transmitter output power.”

The ARRL maintains that proposed deletion of the APC requirement for amateur SS communications is timely and necessary, stating that the ARRL’s Petition showed that the APC requirement has, since it was first imposed in 1997, “been impractical of compliance; unnecessary in order to protect other Amateur Radio operations or the operation of any licensed radio service sharing certain Amateur Radio allocations; and it has served as an unintended, but effective deterrent to Spread Spectrum experimentation in the Amateur Service.”

Pointing out that the FCC has revisited the rules governing amateur SS communications several times, the ARRL notes that to its knowledge since the first SS operation was authorized by the Commission, “has anyone provided documentation of harmful interference from Amateur SS communications to narrowband amateur operation, nor to any authorized radio service operating in the same spectrum. Neither, as far as ARRL is aware, has there ever been an allegation of actual interference to any Part 15 device or system operating at 902-928 MHz or 2400-2450 MHz from an Amateur SS system.”

In 1995, the ARRL proposed changes to the SS rules, including was a suggestion to incorporate APC for SS communications. Previously, the SS rules [then Section 97.311(g)] simply limited stations using SS emissions to 100 W. “It was believed at the time that APC would be a technical implementation of the fundamental, overarching requirement in the Amateur Rules that at all times an amateur station must use the minimum transmitter power necessary to carry out the desired communication,” the League stated in its comments. “The ARRL believed at the time that APC for SS could be accomplished technically. It was not, however, ever suggested by ARRL or the Commission that APC was necessary to avoid interference. Quite the contrary; the Commission concluded that SS communications were entirely compatible with other operations on the same frequencies.”

The ARRL maintains that the Commission should avoid the imposition of an effectively arbitrary power limit while eliminating the APC requirement, saying that doing so “is arguably substituting one disincentive to SS experimentation with a different one. Such would be antithetical to the goal enunciated by the Commission in the Notice, which is to ‘encourage individuals who can contribute to the advancement of the radio art to more fully utilize SS technologies in experimentation.’ Nor is a power reduction necessarily the ‘balance’ of interests of users in mixed-mode and mixed-service frequency bands ‘until sharing protocols are sufficiently developed to avoid interference’ as the Commission describes the power restriction. No balancing has been shown in 25 years of SS operation to be necessary.”

That said, ARRL told the FCC that it is not presently prepared to argue that a power limit of 10 W PEP output is a substantial handicap to SS experimentation: “While the proposed 90 percent decrease in maximum power output is not viewed as necessary, ARRL is willing to accept the restriction presently, subject to revisiting the matter after some reasonable experience is gained with it. The Amateur Service can, in the meantime, ascertain (1) whether or not the reduced power limit is or is not a substantial disincentive to expanded SS experimentation, and (2) whether or not increased power can be implemented without a risk of additional interference to other amateur stations and other radio services in the bands in which SS is and will be deployed.”




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