IEEE BTS Symposium Examines Alternatives to RF Spectrum Constraints

WASHINGTON—After a four-year pandemic-driven hiatus, the IEEE Broadcast Technology Society’s Fall Symposium—a discussion board for the trade of details about the most recent developments in broadcasting expertise—has re-emerged, with little indication that there had been an interruption in what has been a fall custom for the reason that Nineteen Fifties. The Nov. 14-15 occasion, by the NAB at their new headquarters constructing, attracted almost 90 engineers, tools producers and teachers from 10 states and 6 international nations, with some travelling from as distant as Italy, Switzerland, and Argentina. Sessions coated a variety of matters targeted on the most recent in content material supply applied sciences, in addition to issues and points difficult at present’s broadcasters. While some material—similar to conserving a broadcast facility protected from hackers—was widespread to either side of the aisle, tv was undoubtedly out in entrance when it comes to the variety of shows, with greater than half being TV-specific. And whereas ATSC 3.0 was an enormous matter of debate, it was not the unique focus.The Tale of Télé-QuébecGuy Bouchard, a broadcast advisor previously answerable for the digital supply infrastructure at Canadian broadcaster, Télé-Québec, addressed a problem created by the FCC’s reapportioning of C-band satellite tv for pc spectrum utilized by broadcasters.In February 2020, the FCC adopted new guidelines for the three.7 to 4.2 GHz C-Band that allotted the decrease 280 MHz of that band for terrestrial wi-fi use. This pressured current satellite tv for pc operators to repack their operations into the higher 200 MHz of the band, from 4.0 to 4.2 GHz, in accordance to Bouchard, who famous that this pressured transfer created an operational downside for some broadcasters, together with Télé-Québec, a public TV community in Montreal with a government-funded instructional mandate to air all programming in French. Télé-Québec is accessible on cable, over-the-air, and now by way of OTT, masking 96% of the Quebec inhabitants and Bouchard mentioned that though solely about 7% of its viewers obtain Télé-Québec by way of antennas, that viewers was necessary. “That quantity could be very steady; it hasn’t shrunk (and) we wished to maintain those that grew up watching us,” he mentioned.To serve the OTA viewers, Télé-Québec makes use of 18 transmitter websites, all related to the printed middle by C-Band satellite tv for pc, with two-thirds of these transmitters in distant places with out entry to fiber or high-speed web connectivity. All of the websites have been outfitted with 4.5-meter satellite tv for pc antennas and that these had proved sufficient till the C-Band repack. “The websites obtain their feeds from Galaxy 19,” he mentioned, including that whereas Télé-Québec providers shared a transponder with one other consumer, the decreased energy density had probably not been a think about delivering dependable alerts to the OTA transmitters.“We had a 4 to six dB hyperlink margin, which was acceptable beneath most situations,” mentioned Bouchard.Guy Bouchard (Image credit score: James O’Neal)Télé-Québec’s studio-to-transmitter issues arose when the sharing of C-Band spectrum with 5G terrestrial wi-fi carriers started.“Sharing bandwidth with a cellphone firm is a bit like sharing a banana with a gorilla,” he noticed, stating that to decrease interference from close by wi-fi units on adjoining frequencies, heavy filtering had to be added to satellite tv for pc dish LNBs (low-noise block downconverters), and these filters significantly decreased the hyperlink margin.“Ordinarily, there’s no actual filtering on the enter of an LNB,” mentioned Bouchard. “That’s why you will get a very low noise determine,” he added, noting that whereas the 12-pole band-stop filters that have been put in forward of the LNBs have been very efficient in blocking 5G interference, they decreased the LNB acquire by a couple of dB.“This lowered the efficient aperture of the satellite tv for pc antenna,” he mentioned.While the efficiency discount might be tolerated beneath most situations, a moist snowfall was now the demise knell when it got here to delivering programming to the transmitter websites.Sharing bandwidth with a cellphone firm is a bit like sharing a banana with a gorilla.”Guy Bouchard“Sticky snow is the worst issue affecting low-margin C-Band service,” he mentioned. “It distorts the form of the obtain dish, decreasing its acquire and causes outages lasting wherever from 20 minutes to an hour.” Bouchard mentioned that whereas dish deicers labored, they might be overwhelmed by heavy snowfalls.“While they decreased the period of outages, the deicers didn’t eradicate them.”SRT to the RescueBouchard mentioned that whereas the apparent resolution can be to improve satellite tv for pc supply hyperlink margins by putting in bigger dishes, this was not a very viable possibility.“We had 18 transmitter websites to take into account,” he mentioned. “And primarily based on the comparatively small viewers served, the big expense related to putting in bigger dishes can be troublesome to justify.”Bouchard mentioned that after some investigation, Télé-Québec opted to check out a reasonably new expertise—safe dependable transport or “SRT”—as a less expensive resolution. He defined that SRT, which mixes low-latency streaming with superior expertise to deal with lacking packets to guarantee information transmission high quality and continuity of service, appeared supreme for delivering programming over the marginal web supply paths that existed on the majority of its transmitter websites.“With SRT, the payload is distributed by way of UDP (consumer datagram protocol) and stream management packets are despatched by way of TCP (transmission management protocol),” he defined. “A stream management function permits the usage of error detection and supplies retransmission of lacking packets.”Bouchard reported that in a trial implementation at Télé-Québec, SRT had confirmed to be very dependable instead for delivering programming to transmitter websites. “We did have questions on how effectively it will carry out, however after the preliminary trial no artifacts have been reported and no alarms have been acquired” he mentioned, noting that reliability was confirmed even over the poorly performing Internet paths at among the transmitter websites.“Our resolution to the decreased hyperlink margin problem was to proceed to ship programming by way of C-Band satellite tv for pc, however to again this up with an SRT-encoded compressed feed going by way of the general public Internet,” mentioned Bouchard, explaining that the primary supply path continues to be by way of satellite tv for pc, however when the dish sign turns into unstable, the transmitter feeds failback to the Internet-delivered video and audio.He mentioned that whereas extra testing is required, evidently the SRT-encoded feeds are for now a viable various to retrofitting transmitter websites with bigger satellite tv for pc dishes.Asked about whether or not he thought that Télé-Québec may finally discontinue satellite tv for pc linkage to their transmitter websites, Bouchard mentioned that whereas this was not a consideration at current, given the success of the SRT-implemented supply to this point, it is perhaps one thing to take into account. “For now, SRT transmission is a viable possibility to enhance low-margin satellite tv for pc web site reliability.”Other television-related shows on the symposium included the addition of DRM (Digital Radio Mondiale) digital radio service to ATSC 3.0 tv transmissions, methodologies for flash-cutting to NextGen TV supply, seamless insertion of adverts in streamed video, ATSC 3.0’s datacasting potential, concerns in retrofitting or changing of transmission programs, and figuring out the impression of adjoining channel interference in ATSC 3.0 transmissions.   Special RecognitionA particular function of all BTS Symposiums is the popularity of a person who has made vital contributions within the trade, with the presentation of the Jules Cohen Award for Outstanding Broadcast Engineering. TV Tech columnist Doug Lung receives the 2023 Jules Cohen Award for Outstanding Broadcast Engineering from IEEE-BTS President-elect Tom Couglin.   (Image credit score: James O’Neal)The 2023 recipient was H. Douglas (Doug) Lung, vice chairman of Broadcast expertise for NBC Universal Local, and likewise a long-time TV Tech columnist. The award relies on an engineer’s integrity and professionalism, together with the standard and thoughtfulness of his or her work, and was established in 2015.This is Lung’s second trade recognition acquired this 12 months; on the NAB Show, he acquired the NAB TV Engineering Excellence Award.

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