NAB: Gap Fillers Could Improve DTV Coverage

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For several years I've been writing about echo-canceling on-channel repeaters (OCRs) for DVB-T. I reported on an echo-canceling OCR for ATSC based on Korean ETRI technology a few years ago, but until now it has not appeared in an actual product for sale in the U.S.

At NAB, Axcera said it is shipping an on-channel OCR now at a very reasonable price. The OCR has been tested at transmitter power levels between 30 and 50 watts, but it is available for output power up to 100 watts if sufficient receive to transmit antenna isolation is available. This transmitter is not based on the ETRI technology. Acrodyne Industries (AI) was showing an echo-canceling OCR using ETRI technology that should be available soon.

Where higher powers are needed or the delay in the echo-canceling OCR will cause interference, DTS is an option. Harris was showing a low power version of its Maxiva DTV transmitter in an outdoor enclosure with air conditioning. The box with AC was smaller than the HV power supply used in high power IOT transmitters. Rohde and Schwarz also had an outdoor enclosure, with a 900 watt transmitter in it that could be used in a DTS.

In addition to the ATSC Mobile DTV on-channel OCRs, there was a wide range of DTV LPTV transmitters and DTV translators available from vendors including Larcan, K-Tech and others.

These low power systems provide a way to fill in gaps in single transmitter DTV coverage. However, before broadcasters can deploy this technology effectively FCC procedures for these low power systems need to be streamlined so they can be deployed quickly in areas where coverage is a problem. I discussed the idea of having on-channel transmitters below a certain power level (1000 watts ERP seems reasonable at UHF) authorized through a simple on-line filing process where they are registered under the main station license instead of requiring separate individual authorization processed under traditional broadcast licensing approaches. If the FCC is able to move quickly, some of these transmitters could be operational before the June 12 deadline. I'll have specifics on this proposal in next week's RF Report.

Doug Lung
Doug Lung
Contributor

Doug Lung is one of America's foremost authorities on broadcast RF technology. As vice president of Broadcast Technology for NBCUniversal Local, H. Douglas Lung leads NBC and Telemundo-owned stations’ RF and transmission affairs, including microwave, radars, satellite uplinks, and FCC technical filings. Beginning his career in 1976 at KSCI in Los Angeles, Lung has nearly 50 years of experience in broadcast television engineering. Beginning in 1985, he led the engineering department for what was to become the Telemundo network and station group, assisting in the design, construction and installation of the company’s broadcast and cable facilities. Other projects include work on the launch of Hawaii’s first UHF TV station, the rollout and testing of the ATSC mobile-handheld standard, and software development related to the incentive auction TV spectrum repack. A longtime columnist for TV Technology, Doug is also a regular contributor to IEEE Broadcast Technology. He is the recipient of the 2023 NAB Television Engineering Award. He also received a Tech Leadership Award from TV Tech publisher Future plc in 2021 and is a member of the IEEE Broadcast Technology Society and the Society of Broadcast Engineers.