Technology

If I understand it, the title while technically accurate, may be a little misleading.

And to be clear, it's very possible I'm misunderstanding it, and a brief Google search doesn't turn up a whole lot of good information in a format that's easily digestible to me.

When most people hear "gps alternative" I think most of us are picturing some kind of system that will tell you where in the world you are.

It seems to me that BPS is mostly concerned with time and not location.

Gps relies on having very accurate time information, you need to know exactly where the satellites are supposed to be at any given moment, and since they're whizzing around the earth every 12 hours or so, you need to know exactly when it is to know where those satellites are supposed to be in order to properly triangulate a position from them.

So since we have these super accurate clocks flying around overhead beaming out time information, a lot of other critical infrastructure that relies on accurate timing has just latched onto using those time signals because they're already there, no need to reinvent the wheel and come up with your own timing system.

But since GPS is theoretically susceptible to jamming, anti-satellite weapons, etc. we need a backup time signal in case gps goes down.

And since we already have television stations everywhere already broadcasting all kinds of digital data, we can just kind of piggyback off of them to broadcast the same sort of timing information you'd get from GPS.

I'm unclear whether it could actually be used for navigation, the name (Broadcast Positioning System) would seem to imply that it can, but I can't seem to find anywhere that's talking about it being used in that way.

In theory I suppose it can, no reason you can't triangulate your position from some radio towers. In at least one sense it's probably easier than satellite because those towers aren't moving much (maybe swaying a few feet in the wind or so, but otherwise they're about as stationary as anything is on this rock hurtling through space) so they make for a nice fixed reference point.

On the other hand, I suspect there's kind of a line of sight issue. In general there's not much between you and a gps satellite except for a few thousand miles of atmosphere, that signal is coming in a straight line down to you from space. That makes the math nice and easy.

That may not be the case with a TV signal, theres a good chance that there's all kinds of buildings, hills, valleys, etc. between the tower and you, and so it's harder to know if that signal is coming to you in a straight line or if it took a longer route and bounced around off of some hillsides and skyscrapers.

If it does bounce around, it takes longer for the signal to reach your device, which would make the calculations show that you're further away from the tower than you are.

It's also not at all a global system. It's part of the ATSC 3.0 standard, which is mostly only used by North America and South Korea, the rest of the world uses different broadcast standards (that may or may not have similar provisions, I haven't looked into them) so if you're not in one of those places, you're probably not going to be able to make use of BPS in any capacity.

Again, I'm a bit out of my depth here, I've said a lot of words, but I don't have great confidence in a lot of it, I didn't do any deep research into any of this and a lot of this was just me throwing thoughts out there. If anyone knows this stuff better than I do I'm excited to hear from you and for you to tell me what I'm wrong about.