ARRL

News

New 70 cm Coordination Agreement Reached for New England

07/18/2008

In the next step of developing a long-term procedure to mitigate interference to the Air Force PAVE PAWS radar site at Cape Cod Air Force Station in Massachusetts, the ARRL has brokered a deal that will allow new coordinations to be considered by the New England Spectrum Management Council (NESMC) on the 70 cm band.

ARRL Regulatory Information Manager Dan Henderson, N1ND, has been engaged in discussions with Lou Harris, N1UEC, of NESMC; USAF Colonel Chris Gentry, commander of the Cape Cod PAVE PAWS Radar installation, and Dave Pooley of Air Force Space Command Headquarters, to craft additional procedures that would allow NESMC to consider new or modified 70 cm repeater applications.

"The plan being put into place will allow NESMC to resume 70 cm coordination while putting into place some checks and procedures which will allow the Air Force to be notified when a new repeater is going on the air within the area around the radar sites," Henderson said. "NESMC continues as the frequency coordinator for amateur repeaters, which is their role."

The ARRL will work with NESMC on Longley-Rice modeling to obtain an estimated signal strength at the radar of the new repeater. Once this occurs, Henderson said the ARRL will "then make a recommendation -- based on our knowledge of current repeater signals -- if the proposed repeater should be at or near limits that that should allow it to operate without interference to the radar."

Henderson added that this is not an exact science: "Some levels of degradation of the radar receiver levels are only detectable by precise testing. The unit of the Air Force that provides that testing only visits the Cape Cod site about once a year. It is possible that a repeater that had been in operation for a while under the new procedures would have to address an interference issue when that future testing is performed."

Calling it "fortunate" to have Harris, Pooley and Skinner involved in the process, Henderson said, that if successful, "The procedures being put into place can serve as a model for addressing the same issues in other situations which might arise, such as the mitigation project around the PAVE PAWS site at Beale Air Force Base in California."

Part of the new agreement includes the ARRL serving as the point of contact for the Air Force if new interference is detected. "The ARRL is providing a mechanism whereby and future interference issues can be immediately addressed and hopefully resolved," said Henderson. "It makes sense to have a 'first step' whereby an amateur is given the opportunity to address concerns before a more formal FCC interaction would have to be considered by the Air Force. This plan hopefully provides that step."

The agreement does not inject the ARRL into a formal role in repeater coordinations; the role of the League in the coordination process will be simply to provide the NESMC coordinator with an assessment of the proposed repeater's signal strength, as well as potential for interference at the radar site. "While we do not have the specific receiver sensitivity requirements, Air Force officials have indicated our previous calculations for repeaters already involved are 'in the ball park,'" Henderson stated. "We should be able to provide NESMC with a relatively informed assessment for any new repeater, but the final decision on whether to coordinate a repeater remains in the hands of NESMC."



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