GPS Indoors-how does it work?
- Thread starter npalen
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its not line of sight. it works the same way your gps in the car works if you go through a tunnel or the way it works on a submarine.
Ksc said:
... really ... :shock:
It is line of sight, windows don't obstruct the signal like concrete and gerters. Submarines use sonar and precise mapping under water (and other tech), m-band gps is military grade and submarines can only use it when surfaced or at perscope depth, gps does not penetrate water, totally different than our civilian gps.
When you go through a tunnel agps usually kicks in, assisted gps... blah... blah blah...
:mrgreen:
ianwood
Taco Wrangler
Ksc said:
GPS is LOS. Almost all satellite services are. It generally doesn't work indoors though many receivers can pick up a couple SVs through windows or even the roof depending on construction. At 1.2 and 1.5GHz, there is some room to penetrate thinner porous materials but it is not designed for indoor use.
The navigation system in your car uses an IMU and magnetometer to figure out your heading and rate of motion when it loses GPS signal such as when you drive into a tunnel. And as far as I know, submarines have to surface to get a GPS fix and use IMU based navigation and dead reckoning when submerged.
Cr8tive_leo said:... really ... :shock:
It is line of sight, windows don't obstruct the signal like concrete and gerters. Submarines use sonar and precise mapping under water (and other tech), m-band gps is military grade and submarines can only use it when surfaced or at perscope depth, gps does not penetrate water, totally different than our civilian gps.
When you go through a tunnel agps usually kicks in, assisted gps... blah... blah blah...
A-GPS is really only used to facilitate a faster time to first fix and not filling in GPS gaps. Cellular triangulation and WiFi location are also often baked into non-GPS location services.
Well then I'm wrong. Although it doesn't explain how I get perfect GPS lock in the local high schools gym. Thing has no windows and it's a concrete bunker. Literally a bunker. It's a hurricane shelter as well.
ianwood
Taco Wrangler
Ksc said:
Concrete is porous. I get 7 or 8 satellites in my workshop which has a concrete ceiling.
ianwood said:
... Hmmm ... I'd look it up to be sure there. Just saying. AGPS is called Assisted Gps for a reason.
'...Cellular triangulation and WiFi location are also often baked into non-GPS location services....' That's AGPS right there, when gpS signal is bad, or having problems. Has nothing to do with faster first fix.
I've been decoding nmea output for what seems like eons. Don't argue, listen to the master... LOL... :ugeek:
Cr8tive_leo said:ianwood said:
... Hmmm ... I'd look it up to be sure there. Just saying. AGPS is called Assisted Gps for a reason.
'...Cellular triangulation and WiFi location are also often baked into non-GPS location services....' That's AGPS right there, when gpS signal is bad, or having problems. Has nothing to do with faster first fix.
I've been decoding nmea output for what seems like eons. Don't argue, listen to the master... LOL... :ugeek:
There's definitely no substitute for being confident and assertive - especially when you are completely wrong. A-GPS has everything to do with faster initial fix - that is what it is for. If you had looked it up you would have discovered that for yourself.
npalen said:
The modern chips are are very sensitive and low-noise devices, able to pick up the weak signals that penetrate or leak into structures remarkably well.
sar104 said:
LOL... here's a hero cookie. Agps is useless when there is no wifi or cell reception.
Cr8tive_leo said:
A-GPS simply speeds up acquisition of the almanac and ephemeris data via cell and/or wifi. Lack of those doesn't prevent GPS signal lock though, and the presence of them is not a substitute for GPS, since they do not actually provide location data.
Cr8tive_leo said:sar104 said:
Exactly, that's why it's called Agps.
OK - so if you understand that A-GPS is just a mechanism to speed up GPS signal lock, and not an alternative location service, then what was the point of your first post in which you argued the exact opposite?
