VTCifer t1_iwroyhp wrote
Reply to comment by Kooky_Support3624 in Researchers have developed an alternative positioning system that is more robust and accurate than GPS, especially in urban settings. The working prototype that demonstrated this new mobile network infrastructure achieved an accuracy of 10 centimeters. by the_phet
>Civilian GPS has limited number of satellites they are authorized to connect to at a time. Military GPS can connect up to 24 satellites at a time for an accuracy better than 10cm with better response time. Still cool to see alternatives to DoD dependent technology.
Yeah, going to need a citation on that.
1- GPS receivers don't 'connect' to GPS satellites. The GPS satellites are (for the nature of receivers) broadcast only.
2- The US Air Force has only committed to keeping 24 satellites in total operational 95% of the time. There's actually only 31 actually flying satellites currently. No way you could receive signals from 77% of the satellites in orbit at the same time ~50% of them are going to be below the horizon at any given time, and they operate on line of sight. (?probably? slightly less than 50% due to curvature of the earth)
Kooky_Support3624 t1_iwrr4wi wrote
The citation is that I am a SME on avionics. All the GPS modules I have worked on have potential for 24 connections(channels) at a time, typically you will never see more than 18 at any one time. It is a one way connection yes, and they use something similar to frequency hop to effectively encrypt all but 3 or 4 for civilian use.
Edit: for further clarification, they have to recieve a steady signal before they use pings from any particular satellite. That confirmation process is what I am referring to as connecting.
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