Kooky_Support3624 t1_iwqm7gi wrote
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.
VTCifer t1_iwroyhp wrote
>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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