21–30 of 58 posts
Now I'm wishing there was a setting in mapping applications on my phone that changed that the shape used for position uncertainty, from a circle to these arc-intersection shapes.
Earlier quoted context omitted.
GPS was built primarily for the military and the signals available for civilian use were crippled to reduce accuracy. GPS receivers that provided high accuracy fell under the ITAR rules (ie you needed proper licensing to trade them) Over time such restrictions have largely been lifted, but there are still US export controls on GPS receivers with particular features, such as those designed for use in high speed aircra…
> those able to decode the still-military-only encrypted signals How? I was under the impression that military-only signal was encrypted. And if someone breaks that encrpytion, blame should go to the poor handling of encryption rather than the person breaking it? Analogy : if you leave a classified document on the train and a passenger reads it, whose fault is it?
I heard that GPS is one of the few applications in daily life that needs to consider relativistic effects. So, the generated data must have already excluded these relativistic effects, right?
What generated data are you talking about and who was it generated by?
If you mean the output of commercial GPS units, then yes, all manner of error inducing effects have been compensated for in post aquisition processing that generates output.
This article is about raw GPS data .. which is a collection of raw data streamed from multiple satellites that then requires processing to generate an output, and quite often additional inputs from ground stations | naval corrections to improve accuracy.
There are many different GPS instrument providers who all do broadly similar things .. the devil is in the details.
Several peer comments linked to https://ciechanow.ski/gps/ it's a good read.
I heard that GPS is one of the few applications in daily life that needs to consider relativistic effects. So, the generated data must have already excluded these relativistic effects, right?
For anyone wanting to build their own GPS receiver, here's a fully open source project that explains a great deal of the theory too: http://www.aholme.co.uk/GPS/Main.htm
Earlier quoted context omitted.
Not GP but modern GPS / GNSS manufacturers intentionally do not allow their devices to function over some speed (1000 mph or something like that). So they won't work on warheads as part of a guidance system.
I never really thought of that. That's a pretty interesting restriction. Although any party with access to warheads that can fly 1000+ mph probably can bypass the GPS restriction, no?
Android provides carrier phase access for a while now, and with that relative positioning between such devices in about the same neighborhood can be done with enough precision that you have to care about where in the device the GNSS antenna lurks. That alone isn't too fancy; it gets good once you throw in the accelerometer and gyroscope in each device. Because with that you get this not only in realtime, but also wit…
Sounds interesting! Does this approach work in indoor scenarios? Would you mind to provide some further links/papers to this topic?
For anyone wanting to build their own GPS receiver, here's a fully open source project that explains a great deal of the theory too: http://www.aholme.co.uk/GPS/Main.htm
I find the project it links to (and admits to be inspired by) even more impressive: https://lea.hamradio.si/~s53mv/navsats/theory.html