More than 20 years ago, in these pages, we referred to television broadcast signals as “signals of opportunity” that might be used for positioning, navigation and timing (PNT). Since then, several other signals with a different primary purpose have also been considered as sources of PNT, and some have been used routinely for years now, such as WiFi routers for indoor navigation. On Feb. 26, 2025, the National Association of Broadcasters (NAB) filed a petition for rulemaking with the Federal Communications Commission (FCC) for television to transition to a new standard, ATSC 3.0, that enables what they call Broadcast Positioning System (BPS), as a way to enhance GPS resiliency. I asked NAB’s chief technology officer and executive vice president, Sam Matheny, to answer a few questions about the organization’s proposal. In next month’s issue, we will present a different perspective on it.
<p><strong>Question: Briefly, what is the history of the relevant standards?</strong></p> <p><strong>Answer: </strong>The Advanced Television Systems Committee (ATSC) is an international standards development organization. ATSC developed ATSC 3.0 as the “next-gen” standard, and the International Telecommunications Union (ITU) adopted it as a recommended digital broadcast standard in 2020. Broadcasters in the United States began experimental ATSC 3.0 transmissions in 2016, and there are currently more than 100 transmitters broadcasting in 80 markets. Other nations currently using or considering ATSC 3.0 include Brazil, India, South Korea, Canada, Mexico, Jamaica and Trinidad and Tobago. NAB’s petition to the FCC requests permission to fully transition to ATSC 3.0 by 2030.</p> <p><strong>Q: Briefly, what is the history of the BPS project/proposal?</strong></p> <p><strong>A:</strong> BPS is a datacast application that uses ATSC 3.0. We at NAB authored a seminal paper on BPS in 2021 and built our first prototype in 2022. We put our second prototype on the air in 2023. We signed a Cooperative Research and Development Agreement (CRADA) with the National Institute of Standards and Technology (NIST) in 2024 and published our first joint paper earlier this year. The paper concludes that “the stability of BPS time transfer is comparable to or better than GNSS, making BPS a viable complementary PNT solution when GNSS is unavailable.”</p> <p>Our petition to the FCC highlights a transition to ATSC 3.0 that enables the nationwide deployment of BPS.</p> <div class="wp-block-image"> <figure class="aligncenter size-full"><img fetchpriority="high" decoding="async" width="600" height="340" src="https://coordinates.net/wp-content/uploads/2025/04/HighResFigure2_TimeDifference_600px.jpg" alt="BPS time is comparable to dual band GPS (L1/L2) time. The data are recorded as 10-minute averages. (Graphic: National Association of Broadcasters)" class="wp-image-109698" srcset="https://coordinates.net/wp-content/uploads/2025/04/HighResFigure2_TimeDifference_600px.jpg 600w, https://www.gpsworld.com/wp-content/uploads/2025/04/HighResFigure2_TimeDifference_600px-300x170.jpg 300w, https://www.gpsworld.com/wp-content/uploads/2025/04/HighResFigure2_TimeDifference_600px-245x139.jpg 245w" sizes="(max-width: 600px) 100vw, 600px" /><figcaption class="wp-element-caption">BPS time is comparable to dual band GPS (L1/L2) time. The data are recorded as 10-minute averages. (Graphic: National Association of Broadcasters)</figcaption></figure></div> <p><strong>Q: What is the motivation for broadcasters to implement BPS? What’s in it for them?</strong></p> <p><strong>A:</strong> BPS will further secure television broadcasters’ role in the fabric of U.S. telecommunications. We also witnessed the innovation around GPS, with more than 7 billion GPS receivers being built into myriad devices. We’d like to see BPS experience similar innovation, which will bring new business opportunities. We believe that there is an opportunity for a public-private partnership with the government to deploy BPS for economic and national security.</p> <p><strong>Q: What have your tests so far shown regarding the timing accuracy of your signals? How much more R&D is required?</strong></p> <p><strong>A:</strong> We’ve completed a wide variety of testing over the years, but probably of most interest is the work done with NIST. They ran common-view experiments using the BPS signal transmitted from KWGN, a TV station in Denver. Receivers were placed at two different facilities equipped with NIST timescale. Their Boulder facility is 30 km away with non-line-of-sight (NLOS) propagation, and their Fort Collins facility is 106 km away with line-of-sight propagation. A 21-day-long test showed that the time deviation (TDEV) statistics were better than 2 ns for all intervals. NIST also tested the stability of the NLOS signal alone at the Boulder facility and found that the TDEV statistics were better than 3 ns.</p> <p><strong>Q: How can BPS help improve GNSS resilience and integrity?</strong></p> <p><strong>A:</strong> BPS functions completely independent of GNSS, so in the event of an acute GNSS disruption or catastrophic outage, BPS can be a resilient secondary source of timing for critical infrastructure (CI). Integrating BPS into CI applications also makes GPS a less attractive target for intentional disruption. Additionally, being independent means that BPS and GPS can work together in a hybrid mode, where, for example, BPS can help detect jamming and spoofing of GPS.</p> <div class="wp-block-image"> <figure class="aligncenter size-full"><img decoding="async" width="600" height="340" src="https://coordinates.net/wp-content/uploads/2025/04/HighResFigure3TDEVStatistics_600px.jpg" alt="Time deviation (TDEV) statistics of BPS is less than 3 ns, even for the NLOS test scenario. (Graphic: National Association of Broadcasters))" class="wp-image-109699" srcset="https://coordinates.net/wp-content/uploads/2025/04/HighResFigure3TDEVStatistics_600px.jpg 600w, https://www.gpsworld.com/wp-content/uploads/2025/04/HighResFigure3TDEVStatistics_600px-300x170.jpg 300w, https://www.gpsworld.com/wp-content/uploads/2025/04/HighResFigure3TDEVStatistics_600px-245x139.jpg 245w" sizes="(max-width: 600px) 100vw, 600px" /><figcaption class="wp-element-caption">Time deviation (TDEV) statistics of BPS is less than 3 ns, even for the NLOS test scenario. (Graphic: National Association of Broadcasters))</figcaption></figure></div> <p><strong>Q: What are the main benefits of BPS?</strong></p> <p><strong>A: </strong>The key benefits of BPS include:</p> <ul class="wp-block-list"> <li><strong>Existing infrastructure:</strong> BPS leverages existing television transmission infrastructure making it low cost and easy to deploy. There are more than 1,700 full power TV stations on the air today. These stations, considered critical infrastructure, are designed to stay on the air on a 24 x 7 x 365 basis, including during emergencies.</li> <li><strong>Nationwide coverage:</strong> Television transmissions are “high-power/high-tower” signals that provide nationwide coverage. Their broadcast power can be up to 1 MW and from towers up to 2,000 feet tall. The signals can be received NLOS, including indoors. The strength of these signals makes them difficult to jam or spoof.</li> <li><strong>Frequency diversity:</strong> Television in the United States operates on 210 MHz of licensed spectrum divided into 35 6-MHz channels. There are multiple stations/channels in each market, which offer geographic diversity along with frequency diversity.</li> <li><strong>Passive receivers:</strong> BPS is a broadcast service, just like GPS, and supports an unlimited number of simultaneous users with no bottlenecks or two-way connectivity dependencies.</li> <li><strong>Standards-based:</strong> BPS is based on ATSC 3.0, an ITU-recommended digital terrestrial broadcast standard with the support of a global community and supply chain.</li> <li><strong>Independent:</strong> BPS operates completely independent of GNSS and is a self-synchronizing network that does not rely on Internet or cellular connectivity.</li> </ul> <div class="wp-block-image"> <figure class="aligncenter size-full"><img decoding="async" width="600" height="340" src="https://coordinates.net/wp-content/uploads/2025/04/Figure4_BuildingBlocks_600px.jpg" alt="BPS Installation at WHUT. TV transmission infrastructure is already built out. Only a BPS synchronizer and a reference timing source need to be added. (Graphic: National Association of Broadcasters))" class="wp-image-109700" srcset="https://coordinates.net/wp-content/uploads/2025/04/Figure4_BuildingBlocks_600px.jpg 600w, https://www.gpsworld.com/wp-content/uploads/2025/04/Figure4_BuildingBlocks_600px-300x170.jpg 300w, https://www.gpsworld.com/wp-content/uploads/2025/04/Figure4_BuildingBlocks_600px-245x139.jpg 245w" sizes="(max-width: 600px) 100vw, 600px" /><figcaption class="wp-element-caption">BPS Installation at WHUT. TV transmission infrastructure is already built out. Only a BPS synchronizer and a reference timing source need to be added. (Graphic: National Association of Broadcasters))</figcaption></figure></div> <p><strong>Q: What are the main initial use cases? What are some additional ones that might come later?</strong></p> <p><strong>A:</strong> The initial use case is providing resilient time to CI, which includes the power grid, cellular communications, and financial and data centers. A 2019 NIST study estimated the economic risk of losing GPS at $ 1 billion a day, and in 2024 a National Security Space Association study said the impact of a disruption or loss would be incalculable, so addressing this CI need is vital.<br> Longer term, we see hybrid applications where BPS and GPS are used together. BPS can be leveraged for GPS health monitoring, which could be especially useful for transportation systems and can help identify and mitigate compromised GPS service. Going further, we see applications for positioning and navigation, plus other data services such as AGPS, GPS validation and RTK.</p> <p><strong>Q: How will the BPS service be monitored after full deployment?</strong></p> <p><strong>A:</strong> NAB has developed a cloud-based network operations center (NOC) to monitor the health of the BPS-enabled TV stations. As part of our leader-follower construct, TV stations in the BPS mesh network measure each other’s emissions and send the data to the NOC, which can identify any issues.</p> <p><strong>Q: Which television manufacturers have expressed interest so far?</strong></p> <p><strong>A:</strong> Hisense, LG, Panasonic, Samsung, Sony and TCL are already selling NEXTGEN TV sets. It is important to note that these televisions don’t use BPS. They ignore the BPS data and pay attention to the audio and video payload. The reverse is true for a BPS receiver; it ignores the audio and video and simply uses the BPS data. Both services rely on ATSC 3.0, but they use different parts of the signal.</p> <div class="wp-block-image"> <figure class="aligncenter size-full"><img loading="lazy" decoding="async" width="600" height="340" src="https://coordinates.net/wp-content/uploads/2025/04/Figure5_LeaderFollowerMap_600px.jpg" alt="BPS leader-follower mesh network example. WHUT is configured as a leader tower, and WNUV is set up as a follower tower deriving traceable time from WHUT’s signal. At full deployment, the remaining 12 towers in the DC-Baltimore area can also follow WHUT. (Graphic: National Association of Broadcasters))" class="wp-image-109701" srcset="https://coordinates.net/wp-content/uploads/2025/04/Figure5_LeaderFollowerMap_600px.jpg 600w, https://www.gpsworld.com/wp-content/uploads/2025/04/Figure5_LeaderFollowerMap_600px-300x170.jpg 300w, https://www.gpsworld.com/wp-content/uploads/2025/04/Figure5_LeaderFollowerMap_600px-245x139.jpg 245w" sizes="auto, (max-width: 600px) 100vw, 600px" /><figcaption class="wp-element-caption">BPS leader-follower mesh network example. WHUT is configured as a leader tower, and WNUV is set up as a follower tower deriving traceable time from WHUT’s signal. At full deployment, the remaining 12 towers in the DC-Baltimore area can also follow WHUT. (Graphic: National Association of Broadcasters))</figcaption></figure></div> <p><strong>Q: Have you talked to any GNSS receiver manufacturers yet?</strong></p> <p><strong>A:</strong> Yes, we have healthy interest from numerous receiver manufacturers. They see BPS as a nice addition to their product lineups. Conversations have focused on performance and integration.</p> <p><strong>Q: Are there any technical, commercial or legal arguments against BPS? Do you anticipate resistance to your proposal from any quarters?</strong></p> <p><strong>A:</strong> We have not heard any such arguments against BPS. To the contrary, people have been intrigued and supportive of the concept. Recognizing that BPS requires transition to ATSC 3.0, some groups have expressed concerns over the television set upgrade cost for low-income viewers. However, ATSC 3.0 receiver accessories retail for less than $ 100 today, and prices will drop further with scale.</p> <p><strong>Q: How does your proposal address backward compatibility?</strong></p> <p><strong>A:</strong> NAB’s petition calls for all television stations to transition to ATSC 3.0 and for all television sets to be equipped to receive ATSC 3.0. As mentioned earlier, millions of NEXTGEN TV sets are already being purchased, so our petition aligns with natural product replacement cycles, including low-cost converters for older TVs.</p> <p><strong>Q: What is your arrangement and division of labor with NIST?</strong></p> <p><strong>A:</strong> Our CRADA with NIST also includes Nexstar, one of our members. Nexstar operates KWGN where we deployed BPS. NAB provided NIST with BPS receivers and technical support. NIST scientists then performed independent measurements and analysis of BPS using their own techniques and processes. It has been a great experience for us to engage with and learn from the team at NIST. The effort has taught us a great deal about PNT and the capabilities of BPS.</p> <p><strong>Q: Now that you have submitted your proposal to the FCC, what do you expect to be the timeline for approval, implementation and adoption?</strong></p> <p><strong>A:</strong> The FCC follows a notice-and-comment process for adopting changes to its rules, which can take anywhere from several months to more than a year. The FCC previously convened the Future of Television Initiative to investigate issues associated with the transition, which should give us a bit of a head start. In NAB’s petition, we ask the FCC to establish a timeline that would have the top 55 television markets fully transitioned to ATSC 3.0 by 2028 and the remaining markets by 2030.</p> <p><strong>Q: How can the GNSS/PNT community help this project?</strong></p> <p><strong>A:</strong> First, it can support the transition to ATSC 3.0 because BPS relies upon it. We need a full transition to recognize its potential. Next, it can continue to collaborate with us. We introduced BPS at the DOT Roundtable in 2022. Since then, we’ve collaborated with the PNT community on research, scientific papers, product design and deployments. We’ve built BPS together, and now we need to deploy it together.</p> <p><p>The post <a rel="nofollow" href="https://www.gpsworld.com/television-broadcasters-propose-new-pnt-service/">Television broadcasters propose new PNT service</a> first appeared on <a rel="nofollow" href="https://www.gpsworld.com">GPS World</a>.</p></p>
