Do you know what the IODC word in GPS data means? If so, great! If not, head over to see the 32nd of [Michel van Biezen’s] 100-part video series on GPS. You probably want to watch the other 31 videos before he gets too much further ahead of you, too. [Michel] reminds you of that professor you had in college who knows a whole lot about something. In fact, scanning his YouTube channel, he knows a lot about many topics ranging from optics, chemistry, kalman filters, and lots of electronics.
There is a dedicated playlist for the GPS videos dating back to 2016. So 32 videos in about six years. So you might have a little time to catch up. While the first video is pretty introductory as you might expect, by the time you get to video 7 the topics switch to things like the C/A code, BPSK, and gory details of all the frame data, including the IODC word.
We aren’t sure what he’s going to do in the other 68 videos, but it is sure to be interesting if you want to know all about GPS. If you don’t, you might still enjoy some of his playlists on calculus, physics, or other interesting topics. The ones we watched were all very informative.
You hope your GPS data is accurate and it should be, barring any tampering. Decoding GPS isn’t just good for knowing where you are, it also helps you know what time it is to a very tight tolerance.
Is GPS fully open and documented to the point that someone could use generic hardware (computers, microcontrollers, FPGAs etc) and fully open software to receive civilian GPS coordinates? Or are there bits that aren’t available to just anyone (in order to stop someone in a place that doesn’t follow US laws from designing/building a GPS receiver that doesn’t include the mandatory restrictions on speed and altitude)
There are actually home brew GPS receivers. See:
http://www.aholme.co.uk/GPS/Main.htm
https://hackaday.com/2007/10/04/build-your-own-gps-and-glonass-receiver/
Didn’t you watch all 32 videos? :-P
There are multiple GPS decoding projects online.
You could design a system without the restrictions (altitude, maximum speed, etc).
But, then you’d probably want it produced somewhere unless you happen to have your own fab, and that likely means a few choices unless the restrictions are put back.
Or not.
The restrictions are almost meaningless to those that are likely to violate the restrictions anyway.
It turns out if you want to lob balistic mussels at each other that GPS isn’t required, just “better”.
balistic mussels
Hope the don’t have seafood allergies
Correct, the person was referring to mussels from the Baltic Sea. Not in any way to be confused with “ballistic missiles”
https://github.com/gnss-sdr/gnss-sdr
With this software you can use those cheap $30 RTL-SDR v3 dongle and Raspberry Pi to build a software defined GPS receiver that will work in low Earth orbit ignoring any export control restrictions
With that said… the more I work with GPS the more I’m convinced that its some very deep black magic that my phone just works
Yes, you can make a full GPS receiver from the documentation. Only the military signal is secret. The same for glonass, galileo and beidou
Roll your own with SDR https://hackaday.com/2012/04/13/those-usb-tv-tuners-used-for-sdr-can-also-grab-gps-data/