Sinclair Broadcast Group is one of three US networks to start ATSC 3.0 commercial broadcasts from their Las Vegas stations. © Jam
The ATSC 3.0 digital terrestrial standard has passed a major milestone with the first US deployment of a multi-station service exploiting the full scope of the new technology.
The three networks involved are Sinclair Broadcast Group, Nexstar Media Group and The E.W. Scripps Co, which in late May 2020 started transmitting services at their Las Vegas stations. Planning and coordination was led by BitPath, a broadcaster-owned cooperative formerly called Spectrum Company, which has been working with industry consortium Pearl TV to accelerate rollout of NextGen TV across the country. NextGen TV is just another name for ATSC 3.0 and so is confined to that North American digital terrestrial technology, rather than emerging TV services generally. It refers to the more advanced capabilities including support for 4K video and immersive audio.
Another point of confusion is that ATSC 3.0 is really the second generation of the standard rather than the third as the acronym appears to indicate. This is because ATSC 2.0 introduced around 2015 came along when plans for ATSC 3.0 were already quite advanced and so turned out to be just a forerunner to it, a bolt on to ATSC 1.0, without delivering the full range of capabilities.
ATSC 2.0 did deliver some core components of ATSC 3.0, which could then be trialed over ATSC 1.0 infrastructure and enable experience to be gained with prototype systems that were then demonstrated at various trade shows. These included support for NRT (Near Real Time) transmission to improve quality of reception on mobile devices and also interactivity, as well as second screen capability and some service related data gathering and reporting features.
By contrast, the European DVB digital terrestrial standard came out with its full second-generation DVB-T2 in 2009. This is therefore mature and widely implemented, serving as a yardstick against which to measure further progress achieved by ATSC 3.0 over the intervening 11 years.
In many respects, ATSC 3.0 achieves little more than DVB-T2 does when combined with the HbbTV 2.0 hybrid broadcast standard which came along a few years later. Indeed, ATSC 3.0 has incorporated and built on many features of both DVB-T2 and HbbTV 2.0, notably the use of OFDM (orthogonal frequency division multiplexing). OFDM we recall has been deployed in wide area wireless networks, including 4G/LTE and 5G as well as DVB-T2, to boost data rates. It evolved through two related developments, firstly splitting each symbol representing individual bytes of data across multiple low bit rate carriers. These carriers can then be packed closely together with overlaps, greatly increasing both throughput and resilience to inter-symbol interference. This in turn feeds off the second development, the orthogonality, which renders each symbol totally immune from interference from any of the others.
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ATSC 3.0 has naturally made some improvements on DVB-T2, with more options for the coding. It also allows use of higher QAM modulation rates for the symbols at 1024 QAM and 4096 QAM, capable of carrying high data rate 4K UHD content. It still remains to be seen how useful these options are for terrestrial transmission in the UHF band, since they require high signal levels for an error-free reception.
ATSC 3.0 also provides very robust system variants at low bit rates using QPSK modulation. These may provide robust reception to mobile receivers possibly using LDM (Layer Division Multiplex), which is another new feature in ATSC 3.0. LDM is designed to make it possible to combine HD programs for rooftop reception with robust mobile reception as efficiently as possible given current technology. There is also channel bonding so that content can be split across two RF channels, potentially doubling the data rate further, although twin RF tuners are then required.
A notable difference however, not so much related to performance but more implementation, is that in the end the ATSC 3.0 development eventually shied away from the work already done on HbbTV in Europe, put off by the need for a customized HbbTV browser in connected TVs to access the services. If ATSC had followed the HbbTV custom line, developers would have had to learn the HbbTV system in order to develop interactive or hybrid apps and services.
Whether that move away from the HbbTV work delayed ATSC 3.0 further is not quite clear but it has certainly taken much longer than originally hoped. Only a few months ago concerns were still being expressed in the US over the lack of TV models supporting ATSC 3.0. While Next Gen TV is broadcast on existing TV frequencies and therefore to antennas already installed, the new format requires either a new TV or a set top converter box.
The situation improved though in February 2020 when LG Electronics, Samsung, and Sony all announced plans to launch a total of 20 new ATSC 3.0 enabled TV sets later in the year, the first such models for the US market. This came amid rising consumer interest in the associated features, which include support for HDR (High Dynamic Range) and multiple audio tracks, as well as immersive cinema-like surround sound and the 4K resolution.
Against this background, the three networks anticipate roiling out the ATSC 3.0 around the US over the next year or two. “With Las Vegas leading the way, select audiences will soon enjoy a more personalized and immersive experience, with better access to news and media than ever before,” said Chris Ripley, Sinclair’s president-CEO.
Perry Sook, Chairman-CEO of Nexstar, hinted that the Covid-19 pandemic had if anything boosted interest in the service. “During the current pandemic, more viewers are turning to their local broadcast television stations for the latest news and information, and NextGen TV will improve the total television viewing experience.”
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