by sksxihve on 4/13/25, 1:31 AM with 174 comments
by Lammy on 4/13/25, 3:18 AM
“Conventional linear TV services alone (albeit ultra-high-definition) may not be sufficient to sustain the terrestrial broadcasting business which requires a large amount of highly coveted spectrum resources. Intelligent media delivery and flexible service models that maximize the network Return on Investment (ROI) is of paramount importance to the broadcasting industry in the new era.”
That's a lot of fancy words to say ‘we're doing this because it makes us more money’ lol
“Recent studies have shown that interactivity between media customers and service providers and between users themselves will be one of the most important features in the next-generation media service. In this document, this unique opportunity is addressed by defining a Dedicated Return Channel (DRC) system for the next-generation broadcasting system.”
by geerlingguy on 4/13/25, 2:16 AM
Right now it's in the experimental stage, with only 6 towers total deployed (only 5 were operational during NAB, and only one in Nevada... so timing, not navigation yet).
The ultimate plan—which is probably dependent on how well ATSC 3.0 rolls out (which has plenty of hurdles[1])—is to encourage broadcasters to add on the necessary timing equipment to their transmitter sites, to build a mesh network for timing.
That would allow the system to be 100% independent of GPS (time transfer could be done via dark fiber and/or ground-satellite-ground directly to some 'master' sites).
The advantages for BPS are coverage (somewhat) inside buildings, the ability to have line of sight nearly everywhere in populated areas, and resilience to jamming you can't get with GPS (a 100 kW transmitter signal 10 miles away is a lot harder to defeat than a weak GPS signal hundreds of miles away in the sky).
The demo on the show floor was also using eLoran to distribute time from a site in Nevada to the transmitter facility on Black Mountain outside Vegas, showing a way to be fully GPS-independent (though the current eLoran timing was sourced from GPS).
[1] ATSC 3.0, as it is being rolled out in the US, doesn't even add on 4K (just 1080p HDR), and tacks on 'features' like 'show replay' (where you tap a button and an app can stream a show you're watching on OTA TV through the Internet... amazing! /s), DRM (at stations' discretion, ugh), and 'personalized ad injection' (no doubt requiring you to connect your TV to the Internet so advertisers can get your precise location too...). Because ATSC 3.0 requires new hardware, consumers have to be motivated to buy new TVs or converter boxes—I don't see anything that motivates me to do so. I feel like it may be a lot like the (forever ongoing) HD Radio rollout.
by lxgr on 4/13/25, 3:43 AM
In a true "end of history" moment, the US and other NATO members discontinued both of their ground-based systems (which are inherently harder to jam due to their much higher transmission power, since transmitters are not power limited) – Omega in the late 1990s and Loran-C in the early 2010s – in favor of GPS, while Russia kept their equivalent functional, and China completed an eLoran network last year.
Add to that the FAA's reduction of their ground-based VOR/DME station network that lets planes navigate when GPS is unavailable...
GPS jamming, and much more concerningly spoofing, will probably quickly come within reach of non-nation-states and smaller groups of all kinds, and ultimately individual actors, and that can't possibly end well for civil aviation if robust countermeasures don't become available very soon.
by keithwinstein on 4/13/25, 3:25 AM
by RyanShook on 4/13/25, 2:30 AM
by LeoPanthera on 4/13/25, 5:35 AM
It's a travesty that this was ever approved.
by hwpythonner on 4/13/25, 9:01 AM
If it’s not intrinsic to FM, why not use existing cellular towers to do this? They’re everywhere, and phones already receive broadcast messages (like Amber Alerts) even without a SIM (I think) — so it feels like this could be done without needing new radios.
What makes this more accurate than cell tower triangulation today? Is the limitation in timing sync across towers, or something else in how cell networks are structured?
And for indoor use — how does this handle multipath? Reflections from walls or even atmospheric bounce seem like they’d throw off timing accuracy, similar to what messes with GPS in dense areas.
by anonymousiam on 4/13/25, 4:11 AM
by dieselerator on 4/13/25, 6:55 AM
by master_crab on 4/13/25, 2:51 AM
by kristopolous on 4/13/25, 3:30 AM
for people who don't want to watch videos
by teleforce on 4/13/25, 2:18 AM
Typical high end microwave measurement system cost as much as a Ferrari car.
Good cable and connectors can set you back by several thousand dollars.
It's a very good business space prime for disruption (hint SDR - or software-defined radio).
Fun facts, the grand daddy of Silicon Valley start-up is HP (then Agilent, and now Keysight) selling function signal generator.
by neuroelectron on 4/13/25, 3:55 PM
https://www.sparkfun.com/sparkfun-gps-rtk2-board-zed-f9p-qwi...
The datasheet: https://cdn.sparkfun.com/assets/f/8/d/6/d/ZED-F9P-02B_DataSh...
by skissane on 4/13/25, 4:12 AM
by rwg on 4/13/25, 6:11 AM
• ATSC 3.0's physical layer can already transmit GPS time in a way that receivers could get it back out. What BPS brings to the table is a requirement and specification for accurately and consistently filling in the physical layer preamble fields containing the time data, along with a new physical layer pipe (think "low-level data stream") that contains additional information about the transmitter and, optionally, its neighboring transmitters.
• BPS is capable of producing time fixes when the receiver only has a lock on one source. This isn't surprising at all — GPS receivers can do the same thing. But either type of receiver with only one source would see a clock offset proportional to the path delay, which it wouldn't be able to compute and back out without knowing its position.
• BPS is only designed for 2-D position fixes. While that's a reasonable design decision (the vertical position error would be massive), it also makes BPS less useful for the NAB's "indoor positioning for first responders" use case, especially in areas with multi-story buildings.
• The need to receive and process/decode multiple, most likely non-adjacent 6 MHz channels for positioning increases receiver complexity and cost.
• The NAB claims that 1 kilometer of separation between two BPS transmitters is "sufficient for useful position determination." I don't buy it, especially in the face of poor transmitter geometry.
• They note that 16 TV stations in the New York City area broadcast from One World Trade Center, so for the purposes of BPS, they're effectively one station. This kind of transmitter colocation is incredibly common, both in urban areas (ten TV stations broadcast from Sutro Tower in San Francisco) and in more rural areas (six TV stations in the Roanoke-Lynchburg DMA broadcast from towers within ~1 mile of each other on the ridgeline of Poor Mountain). Even if every ATSC TV station became an ATSC 3.0 w/ BPS transmitter, bad transmitter geometries would destroy BPS's position accuracy in lots of markets.
• What's the business case for broadcasters? BPS won't be free for broadcasters to implement, and there doesn't seem to be a path to it generating revenue except for a hand-wavy "maybe one day televisions will be able to determine their locations without Internet connections using BPS, and then broadcasters can do location-targeted advertising with those TVs!"
My uncharitable take is that BPS will never be a usable standalone PNT system. A timing system in the "rebroadcasts GPS" sense? Maybe. Standalone positioning? No way. Broadcasters implementing BPS (or ATSC 3.0 at all) without being forced to by the government? I don't see it.
by WhyNotHugo on 4/13/25, 8:42 PM
by dust42 on 4/13/25, 5:55 AM
Current planning is public availability in 2027-2029.
A good gov presentation with an overview and technical details is here [1].
[1] https://www.gps.gov/governance/advisory/meetings/2022-11/mat...
by fortran77 on 4/13/25, 2:04 AM
by cbsmith on 4/13/25, 7:15 PM
by AndrewKemendo on 4/13/25, 6:30 PM
by publicola1990 on 4/13/25, 2:51 AM
by ConteMascetti71 on 4/13/25, 2:31 PM
by Iwan-Zotow on 4/13/25, 3:16 AM
by throw84848484 on 4/13/25, 7:19 AM