FCC OKs Mods to STL in Dayton

Denies objection from Southwestern Ohio Public Radio
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The FCC said no to a request by Southwestern Ohio Public Radio in Beavercreek, Ohio, to deny an application from Johnson Communications to modify its license for an STL in the Dayton area.

Johnson wanted to change the STL frequency from 948.125 MHz to 951.000 MHz, change the transmitter site and implement other changes.

The decision comes soon after the agency clarified its STL procedures.

In its modification application, Johnson certified that it had completed the FCC’s frequency coordination process with nearby licensees. Applicants also need to make reasonable efforts to avoid interference and resolve conflicts, according to the decision from the Wireless Telecommunications Bureau.

Johnson included a letter from frequency coordinator Terrestrial RF Licensing, which acknowledged objections from Southwestern. The pubcaster claimed the proposed STL frequency change could cause interference to its STL on an adjacent channel centered at 951.75 MHz. TRFL disagreed and concluded that Johnson’s proposal complied with the FCC’s prior coordination requirements.

Southwestern argued that its STL is experiencing a lack of reliability, with irregular dropouts “seemingly caused by interference,” the agency wrote. Southwestern specifically said it was not accusing Johnson of causing that interference but added that it feels the proposed operation with an overlapping of sidebands will hamper its efforts to improve the reliability of its STL. Southwestern believes that there should be 850 kHz separation between the two facilities, and claims that Johnson has not responded to its suggestions to resolve Southwestern’s concerns, according to the commission.

TRFL stated that Johnson’s engineer had offered to arrange a test to determine whether or not Johnson’s proposed operations would cause any interference, but that Southwestern had declined to discuss anything other than Johnson changing its frequency. TRFL concluded that 951.000 MHz is the only available frequency that would be workable for Johnson’s purposes in the Dayton area because the 944 to 952 MHz STL band is crowded there, with 339 licensed paths within the parameters that are relevant to Johnson’s application.

The FCC later asked Southwestern if it could provide additional engineering support of its objection, and said the pubcaster declined. TRFL sent Southwestern a letter reiterating that Southwestern’s transmission difficulties were not attributable to interference and suggesting that the path between Southwestern’s transmitter and receiver might be obstructed by terrain, a problem that could potentially be resolved by raising its transmitter, its receiver or both.

Southwestern then told the commission its STL transmission problems were caused by “one or more factors — to include interference, possible terrain blockage and low link margin.” Southwestern also stated that it had applied to a local government authority for permission to erect a 70 foot tower at its studio, which could potentially improve its link performance.

Southwestern maintained that interference might be why its digital STL link was not performing well and urged the FCC to delay processing Johnson’s application until Southwestern completes its efforts to resolve its link performance problems. Johnson notes that Southwestern didn’t submitted any engineering study demonstrating that the proposed STL modification would cause interference to Southwestern’s STL, nor provided any technical details to support its interference claim.

Since Johnson and Southwestern have been unable to resolve this issue, the FCC looked into the case and determined that Southwestern has not proved the proposed modification of Johnson’s STL would cause or exacerbate any interference problem to Southwestern’s STL. Noting that the two STL signals were also cross-polarized, frequency coordinator TRFL concluded that the resulting difference in signal levels was sufficient to prevent the infringing signal from interfering with reception on an adjacent channel at the victim site. In contrast, noted the FCC, Southwestern has not provided any engineering to support its claims.

The commission decided there’s no reasonable likelihood of Johnson’s proposed STL operation causing interference to Southwestern’s STL and stated that Johnson’s proposal is unrelated to Southwestern’s problems. “The purpose of the coordination process is to resolve technical problems raised by the proposed operation, not to raise unrelated problems a licensee is experiencing,” the agency stated.

So the FCC will process Johnson’s request to modify its STL.

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