I suppose this is an unusual route to target, but why not a celestial rough fix to give an alternate warm start to AGPS.
With the camera, compass, and gyro all that would be required is to lay the phone on its back at night especially in a low light rural area, during the day put the sun in view of the camera(maybe with a lens cover to prevent burnout) this will place the phone within a few km anywhere as long as the clock is accurate. Setting clock is really all GPS satellites do then we compare the results, I am not sure if commercial ITAR compliant GPS receivers output the raw time component. Even if not what is cool is that you can get within about 15 seconds of real time simply by comparing the arc-distance of the moon from other stars and planets with a Napoleonic era sextant and reference book.
If someone can help with the video matching this dev has been very into projects like this and I think would enjoy being part of the first 'sextant' phone https://github.com/kenyoung
With the camera, compass, and gyro all that would be required is to lay the phone on its back at night especially in a low light rural area, during the day put the sun in view of the camera(maybe with a lens cover to prevent burnout) this will place the phone within a few km anywhere as long as the clock is accurate. Setting clock is really all GPS satellites do then we compare the results, I am not sure if commercial ITAR compliant GPS receivers output the raw time component. Even if not what is cool is that you can get within about 15 seconds of real time simply by comparing the arc-distance of the moon from other stars and planets with a Napoleonic era sextant and reference book.
If someone can help with the video matching this dev has been very into projects like this and I think would enjoy being part of the first 'sextant' phone https://github.com/kenyoung