Four-Transmitter SFN Powers NAB Show’s ATSC 3.0 Demos

LAS VEGAS—To provide the RF signals for the “Riding the Road to ACTS 3.0” model train displays, the NAB arranged for a four-transmitter single frequency network (SFN) to be designed and installed at the LVCC to demonstrate both the relative ease with which an SFN could be rolled out using ATSC 3.0 technology and the rock-steady video that the standard delivers to receiving devices that are on the move.

Kelly Williams, the NAB’s senior director of engineering and technology policy, described the project as very rewarding, and stated that even with the miniscule power being delivered by the network’s “transmitters” (they’re actually ATSC 3.0 modulators, or exciters with no power amplifiers added), he was very pleased with the results at all of the receive sites in the cavernous exhibit halls.

“[We found that] the signal had good coverage,” said Williams. “The modulation was set for 16-QAM, as we wanted it to be pretty rugged and robust, and the payload was set at about 10.5 mbps pushing video at about eight, and we’re using Surface Pro tablets with 3.0 dongles as receivers. The results were pretty darn good.”

One of these model railroad demos was set up in the Central Hall Concourse, and two others in the North Hall.

Williams explained that the idea for the SFN to complement the ATSC’s “Road to ATSC 3.0” and “Riding the Road to ATSC 3.0” themes came about in a brainstorming session, and that the time from concept to installation at the LVCC was less than four months.

“Lynn Claudy (the NAB’s senior vice president of technology) conceived [the SFN idea] around the first of the year,” said Williams. “We always want to do something new here at the show, and we knew we wanted to do some sort of ‘on-the-air’ demo, as we’re broadcasters and we’ve done something that involved being on-the-air for the last three years. In noodling it around, Lynn said ‘why don’t we build an SFN?’”

Williams said that John Turner of Turner Engineering was tasked with designing and building the SFN, and once he was on board, things moved out very quickly. Another principal contributor to the demos was Comark, which provided the entire rack of integrated ATSC 3.0 headend equipment and two of the four exciters.

“I think we shipped everything to John by mid-February and here we are today,” said Williams. “John is a master of figuring out how to do things that have never been done before.”

For a comprehensive source of TV Technology’s ATSC 3.0 coverage, see ourATSC3 silo.

James E. O’Neal has more than 50 years of experience in the broadcast arena, serving for nearly 37 years as a television broadcast engineer and, following his retirement from that field in 2005, moving into journalism as technology editor for TV Technology for almost the next decade. He continues to provide content for this publication, as well as sister publication Radio World, and others.  He authored the chapter on HF shortwave radio for the 11th Edition of the NAB Engineering Handbook, and serves as editor-in-chief of the IEEE’s Broadcast Technology publication, and as associate editor of the SMPTE Motion Imaging Journal. He is a SMPTE Life Fellow, and a Life Member of the IEEE and the SBE.