Thread: will GPS always be free?

Yeah, what phord said. The government stopped inducing errors in the system back in 2000 i think. It used to be that non-military systems were accurate to 100 feet. He's further right in saying that there is too much infrastructure to start charging for gps. I will say that gps is not essentially unfunded now that the satelites are in orbit; the cost of maintaining at launching new satelites is easilly in the billions of dollars per year, and when you think of all that is depending on this system, it is good that we are investing such an ammount to keep it running well. Oh yeah, one more thing, the gps guided bombs and such: the military implementation of gps is of a far greater quality than the civilian implementation. Just like civilian nightvision is 4 generations behind the military's 100 grand per special forces operator nightvision the gps is much better, with hardware to overcome gps jamming and greatly increase accuracy. Again, this is quite desirable, we really don't want 1 ton bombs falling from a guided signal that is jammed or inaccurate.

I think a 2,000 pound bomb accurate to within 30 inches will do fine. My hand held GPS displays it accuracy. Often its 20 feet + or - 4 feet. 16-24 feet is good enogh for me. If getting to within 24 feet of something doesn't help, you must suck at life. It even helped me in a corn field maze (don't ask)

Originally Posted by msb5150

Yeah, what phord said. The government stopped inducing errors in the system back in 2000 i think. It used to be that non-military systems were accurate to 100 feet. He's further right in saying that there is too much infrastructure to start charging for gps. I will say that gps is not essentially unfunded now that the satelites are in orbit; the cost of maintaining at launching new satelites is easilly in the billions of dollars per year, and when you think of all that is depending on this system, it is good that we are investing such an ammount to keep it running well. Oh yeah, one more thing, the gps guided bombs and such: the military implementation of gps is of a far greater quality than the civilian implementation. Just like civilian nightvision is 4 generations behind the military's 100 grand per special forces operator nightvision the gps is much better, with hardware to overcome gps jamming and greatly increase accuracy. Again, this is quite desirable, we really don't want 1 ton bombs falling from a guided signal that is jammed or inaccurate.

I don't believe there are seperate civilian and military implementations of GPS. They're the same satellites, just the civilian-accessible signal was degraded. With that degradation now turned off, the civilian and military are on equal footing (well almost - apparently there's a second corrective signal the military uses, and at least within US jurisdiction commercial recievers must be inoperable at high speed)

Also, the cost of maintaining the fleet is apparently apprx. $400 million, including replacing old satellites.

Go Wikipedia
http://en.wikipedia.org/wiki/GPS

Just expanding on what Mushin has said:

There are separate civilian and military signals. The military one is encoded, and the GPS receiver decodes the signal, and uses the time difference between the two signals to get a better accuracy.

The two signals are transmitted on slightly different frequencies, and therefore take different times to reach the surface.

I should add that i'm in the army and our GPS receivers come with crypto so they can decrypt the military signal.

heard too many stories about misguided bombs/missles although those werent probably gps guided.


hrmmm, military gps.... it couldnt be that hard to crack could it?


/runs as men with M16s pop out of black SUVs that just pulled up

thanks all you americans for this service.

The european enion is introducing 'Gallilao' or something similar as far as I know, which is supposedly compatible with GPS, more accurate and intended to prevent the americans from holding a monopoly over GPS. I'm not sure when it's supopsed to go live, but it too will be free to use.

I really do not know if it adds to what Skoprion said or is a separate story, but there are so called 'differential' GPS receivers (which have nothing to do with the old, navi's controlled, differential ground correction signal implementation) but just incorporates two GPS receivers into single unit, and are capable of accuracy of several inches. And, what's most surprising, they are commercial, not to say - they are not cheap...

Gallileo will start in 4-5 years . Technically, US gov descrambled the civilian part of the gps technologiy ( 100 feet accuracy before 2000) when european countries finally decided to build the gallileo. How strange....

Gps won't die because of radar limitations. The FAA's been experimenting ADS-B technology in Alaska since 2001, and Australia does the same in Queensland sinc 2002. Radars can't cover every square inches, they're limited to roughly few hundred miles. With ADS-B, a plane transmits its position, speed, identity to ground stations and to other planes.