PART 2 - GPS absolutely proves globe Earth, rotating Earth, space, orbiting satellites, time dilation (relativity), and gravity.
Flat Earthers like to claim that GPS is a closed source secret to hide that it works off of "muh towers" or "muh balloons." But GPS functionality can be confirmed using open source software and a SDR:
https://gnss-sdr.org/The documentation for GNSS-SDR specifically discusses both time dilation and Doppler, and provides the formulas for both:
https://gnss-sdr.org/docs/sp-blocks/observables/You can literally capture GPS satellite signals then execute the code step by step to watch what is happening. You can find the sections of code which provide time dilation correction and which utilize the Doppler effect and watch the processing unfold. You can also modify the code to remove one or the other and see that the coordinates are no longer correct.
You don't have to appeal to any authority to prove how GPS works. With a compatible SDR you can perform experiments over and over to prove that the satellites are in orbit, prove relativistic time dilation, and thereby prove globe Earth, rotating Earth, space, orbiting satellites, relativity, and gravity.
Flat Earthers have to lie about GPS, like everything else, because GPS kills the disc...dead.
