News TV-signal based BPS tested as fallback for GPS — digital TV infrastructure could come to the rescue if satellites are compromised

[Admin]

The recent NAB show charted progress in developing the Broadcast Positioning System (BPS).

TV-signal based BPS tested as fallback for GPS — digital TV infrastructure could come to the rescue if satellites are compromised : Read more

 

[COLGeek]

Radio resection. Old manual map folks should recognize the concept in play. The more sources used, the more accurate the location. Pretty interesting re-use of current tech.

 

[bit_user]

Hopefully, the U.S. won't need this GPS backup in its home turf, where ATSC 3.0 digital TV signals are found.

Well, if satellites are taken out by either hostile action or perhaps an unusually strong geomagnetic storm, then the scope of the impact could be much larger than the localized jamming incidents referred to by the article.

As for accuracy, there are a couple reasons why approximate accuracy might be good enough. First, it could reassure you that your GPS signal isn't being spoofed. Second, having an approximate location could be enough for a navigation system to lock onto landmarks for fine navigation. GPS-based nav systems already seem to use this trick, affixing your location to the nearest road and using cues from turns. Systems with cameras (e.g. self-driving cars or a smartphone app) could also match visual key points extracted from a dataset like Google's Street View, although that wouldn't work too well when you're not around buildings or other distinct landmarks.

Lastly, recent research has provided new insight into how some migratory birds use the Earth's magnetic field to determine their location. When another positioning system isn't available and weather conditions or foliage prevents using the sun or stars, that seems like a pretty good fallback.

https://phys.org/news/2024-11-magnetic-displacement-held-theories-migratory.html
​

 

[helper800]

Lastly, recent research has provided new insight into how some migratory birds use the Earth's magnetic field to determine their location. When another positioning system isn't available and weather conditions or foliage prevents using the sun or stars, that seems like a pretty good fallback.

​

https://phys.org/news/2024-11-magnetic-displacement-held-theories-migratory.html​

​

Takes me back to the scouts when navigating a mountain with a compass and a topological map. With a topological map in hand I feel relatively confident of my location, lest I am in a plains area with no distinct landmarks, or a dense thicket that disallows for the seeing of landmarks.

 

[bit_user]

Takes me back to the scouts when navigating a mountain with a compass and a topological map.

A magnetic compass only gives you the declination, though. If you had not even a remote idea where you were, then just that piece of information wouldn't enable you to pick the right map to look at and try to match against landscape features.

In the article I linked, the researchers found that the birds they studied are also using magnetic inclination, which enables them to estimate their location with no other information. They were even shown conflicting clues, like stars and magnetic intensity, which had no effect on their choice of which direction to fly.

 

[helper800]

A magnetic compass only gives you the declination, though. If you had not even a remote idea where you were, then just that piece of information wouldn't enable you to pick the right map to look at and try to match against landscape features.

In the article I linked, the researchers found that the birds they studied are also using magnetic inclination, which enables them to estimate their location with no other information. They were even shown conflicting clues, like stars and magnetic intensity, which had no effect on their choice of which direction to fly.

While true, unless I was drugged and placed on a random location on earth, without enough context clues, I would not be able to figure out where I was. It would all depend on whether or not I had maps to determine exactly where I was, and of course, a compass. I regularly play geoguesser as well, but this is a bit beyond the conversation. Birds would know much quicker with no context clues needed.

 

[kanewolf]

Radio resection. Old manual map folks should recognize the concept in play. The more sources used, the more accurate the location. Pretty interesting re-use of current tech.

The key thing that most people don't understand is that GPS is really just very accurate clocks. If there were atomic clocks at the TV transmitters to provide the equivalent time accurate signals, then the TV broadcast positioning could be as accurate as GPS. The GPS receiver does all the hard work. The satellites just say "Here is where I am, and here is what time it is".... Since TV transmitters don't move (unlike GPS satellites), then "Here is where I am" is pretty simple. All you need is the super accurate time that GPS satellites have.

 

[bit_user]

While true, unless I was drugged and placed on a random location on earth, without enough context clues, I would not be able to figure out where I was.

Sure, but that experience doesn't translate to every context where nav is used. Therefore, we need tech based on more than just declination + mapping.

Since TV transmitters don't move (unlike GPS satellites), then "Here is where I am" is pretty simple. All you need is the super accurate time that GPS satellites have.

It'd be slick if BPS could directly complement GPS by telling you the coordinates of each tower, in addition to its GPS-compatible time. Then, by receiving any mix of 3 sources, you'd be able to triangulate your position.

In fact, if you could estimate your distance from just two BPS broadcast towers and then move around enough for an inertial nav + compass to generate more data points, that'd be enough to fix a precise location. Every phone has accelerometers and a magnetic compass. They can also use AR tech (i.e. SLAM) to do much more precise mapping.

Thinking about this a bit more, if you used SLAM + compass over a large enough baseline, then you ought to be able to compute your location using a single GPS satellite or BPS tower. Basically, triangulation can work both ways. You can sit in a single spot and triangulate against 3 references, or you can accumulate at least 3 data points by moving around, so long as you know the relative locations of those points and the distance of each to a single, common reference.