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 Previous: W1HQ Now Up and Running -- on the World Wide Web |  Next: Dive into the Digital Radio Universe with ARRL's VHF Digital Handbook |
The FCC, ARRL representatives and agents of the various US Air Force units working on developing a plan to mitigate alleged interference from 70 cm ham radio repeaters to PAVE PAWS radar systems on both coasts met February 20 via conference call. The purpose of the conference was to review the status of the mitigation plans at both sites: the Massachusetts Military Reservation on Cape Cod and Beale AFB, north of Sacramento, California.
Thanks to the cooperation and assistance of the involved repeater owners on Cape Cod, ARRL Regulatory Branch Manager Dan Henderson, N1ND, said, "I am pleased to be able to pass along that at this time that the Department of Defense has determined that the levels of harmful interference to the PAVE PAWS radar site on Cape Cod have been sufficiently reduced. As part of this determination, they are not rescheduling additional follow-up testing for that area until sometime in 2009."
Henderson said that this decision doesn't mean New England is back to pre-mitigation repeater operation: "Any mitigation steps that have been taken should remain in place. A repeater that has gone off the air should not be simply turned back on at its original power level - its previously determined mitigation standard still applies in order to protect the primary user from harmful interference."
Henderson stressed that the entire process is ongoing. "The high degree of voluntary cooperation shown by the owners of Air Force-identified repeaters has helped demonstrate to the DoD that the amateur community takes its responsibility seriously. This should help us retain access to the band in the long run."
Repeater Coordination
During the discussion of the Cape Cod radar during the teleconference, the ARRL broached the topic of allowing the resumption of coordinating new repeaters on the 70 cm band in New England. The Air Force has agreed in principle to allow the New England Spectrum Management Council (NESMC) to resume coordination efforts under certain conditions. "These include that in addition to NESMC's normal coordination policies, Longley-Rice signal strength plots are prepared to determine expected signal strength at the radar site," Henderson said.
Henderson said that the ARRL has a "fairly good understanding of what strength level at the site should be workable, even though the DoD has not given us specific information on the sensitivity of the radar. The Longley-Rice plots should indicate if the operating parameters of the proposed repeater might be sufficient to prevent harmful interference to the radar site. The Longley-Rice plots are not the 'last word' in the process, but are a good tool giving the repeater owner and NESMC a reasonable assessment of possible problems."
Henderson reiterated that "any specific mitigation number from the Air Force is an exact measurement, not a 'predicted' number from a computer analysis."
Once NESMC approves a tentative coordination, Henderson explained that NESMC would forward the complete information on the new repeater to the Air Force for authorization on a case-by-case basis, as provided for in Title 47 §2.106 Footnote US7. "During a 60 day trial period, the Air Force would contact NESMC for an immediate shut-down of a new repeater causing harmful interference. If that happens the new repeater would have to remain off the air until it can be successfully mitigated."
While this new process is a bit burdensome to NESMC and the repeater owners, it goes a long way toward keeping Amateur Radio in a position where 70 cm operation can grow with careful attention to the effect of our operations on the primary users.
California
During the update discussion of the Beale AFB PAVE PAWS site in California, the DoD was able to report that there was a reduction in harmful interference at the radar, though work remains to be done to bring the situation at that site to a successful conclusion. DoD officials announced that a new round of testing is scheduled during the spring at Beale, and that they will share the results after the next round of testing is complete.
During the teleconference, the FCC reported that it has received excellent compliance in the wake of their phone calls and letters to repeater trustees and owners. This cooperation has made it unnecessary for the FCC to issue any mandatory shut down orders to date. The Commission will continue to be the initial point of contact with the DoD should further mitigation be required based on additional testing at Beale.
The ARRL will continue to work with the FCC, DoD, repeater coordinating groups and individual repeater owners as requested. "Because of the sheer number of 70 cm repeater in that area, the Beale problem is taking longer to resolve," Henderson said. "We will continue to work toward a successful, constructive conclusion for as long as it takes."
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