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Cooperative Effort Under Way to Resolve Potential 70-Centimeter Interference Issue


 ARRL, the FCC, and the US Department of Defense are cooperating in an effort to eliminate the possibility of amateur radio interference on 70 centimeters to a future missile control system at White Sands Missile Range (WSMR) in New Mexico. The Defense Department’s Regional Spectrum Coordinator contacted the FCC in March, seeking information on whom to contact regarding amateur transmissions operational on 70-centimeter frequencies slotted for use on the new control system. The FCC, in turn, asked ARRL to oversee the coordination efforts. It is to be noted that the Amateur Radio Service is a secondary service on the band.

Investigation revealed that the potential problem was not with individual operators or repeaters, but with RF control links at 420 – 430 MHz used to establish a linked repeater system within New Mexico. “Based on the investigation, and with the support of the FCC, the owners of the RF control links being used in the 420 – 430 MHz portion of the amateur allocation within a certain proximity to WSMR are being asked to re-coordinate the link frequency to a new one above 430 MHz,” explained ARRL Regulatory Information Manager Dan Henderson, N1ND.

ARRL enlisted the assistance of the state’s designated repeater frequency coordinator for information on specific links in that part of the band. New Mexico Repeater Frequency Coordinator Bill Kauffman, W5YEJ, agreed to work with the control link operators to find new frequencies that will meet the needs of the link operators.

“Time is a factor in this request,” Henderson said. “The new WSMR systems are in advanced testing and will become fully operational by early summer 2021.” The negotiated deadline for the affected control links to change frequencies is set for May 31, 2021.

“It appears a total of 32 control links will have to be addressed,” Henderson said. ARRL has mailed letters to each of the RF control link operators, based on the recordkeeping of the frequency coordinator, to advise them of the DoD’s request. “Any links with the potential to affect the identified control systems at WSMR still in operation after May 31, 2021 will be subject to action by the FCC.”

Henderson said the changes should have no direct impact on the use of any local repeater, but until all the affected RF control links are transitioned to new frequencies, certain links may be temporarily inoperative. Links unable to be relocated by May 31 will have to be shut down until the situation can be resolved. ARRL will maintain contact with the FCC to advise it of the status of the coordination efforts.



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