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FCC Sets Rules for DTV Distributed Transmission Systems

After releasing a Notice of Proposed Rulemaking (FCC 05-192) three years ago, the FCC has adopted rules allowing broadcasters to use distributed transmission systems (DTS) to improve coverage.

This should come as a relief to broadcasters unable to replicate VHF analog coverage with their DTV contour. Since cable TV is of no use in cars, broadcasters will also need DTS to provide mobile TV coverage in areas shadowed by terrain or buildings. VHF DTV broadcasters in the Northeast, with severely limited effective radiated power levels, will be able to use DTS to increase signal levels in communities near the edge of their contour.

The FCC Report and Order (FCC 08-256) states, "For some broadcasters that are changing channels or transmitting locations for their digital service, DTS may offer the best option for continuing to provide over-the-air service to current analog viewers, as well as for reaching viewers that have historically been unable to receive a good signal due to terrain or other interference."

DTS transmitters will be allowed inside a station's DTV service area contour or within the area defined by the "Table of Distances" proposed in the FCC DTS Notice. The FCC adopted a waiver policy allowing a station to use DTS to "enable it to continue to serve its existing analog viewers who would otherwise lose service as a result of its transition to digital service."

Transmitters in a DTS will have primary regulatory status within the areas the DTS transmitters are authorized to serve.

The Report and Order states that stations who wished to use DTS technology would have to wait until proper forms were available and modified "information collection" requirements were established. It noted that the FCC's Media Bureau would give notice as to when the agency would start taking DTS applications, further noting that under an interim policy, DTS proposals would be evaluated as a request for Special Temporary Authority (STA) operating permission. The Report and Order recognized the fact that some stations could lose audience after the February transition and might wish to use DTS technology to restore service area before FCC rules are finalized. The document cautioned, however, that stations granted STAs for DTS operation would still have to apply for permanent status once rules are in place.

Stations that want to use DTS to expand their DTV coverage to match their analog coverage must apply by Aug. 18, 2009 and commit to building the DTS facility as quickly as possible.

The FCC urged stations to quickly determine if a service loss is anticipated and to apply for an STA for DTS operation under the interim policy "to provide uninterrupted service to the current analog viewers within their analog Grade B contour" after analog service ends.

Commissioner Michael Copps noted that broadcasters may have benefited more from the order had the FCC acted sooner.

"Had we identified these coverage issues earlier, we could have approved DTS months ago and given broadcasters enough time to build out before the transition," Copps said in a statement. "Now that generally will not be possible. Would a truly comprehensive and coordinated DTV effort have identified these issues earlier? We will never know for sure. What we do know is that, in the absence of such an effort, we never gave ourselves a chance."

I'll discuss the technical details of the 56-page Report and Order in a future RF Technology column.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.