guess
#11
07-24-2004 | 11:17 AM
Joined: Dec 2003
Posts: 3,766
From: Georgia, USA
RE: guess
That E-call and Tele-Aid are old stuff. Nothing new. OnStar is even put into Chevrolet pickup trucks. But, communications are not done through the GPS system. GPS is a location system not a communication system. A cell phone is used to call for help after an airbag deploys or to talk to the "traffic center." It forwards your GPS coordinates when it calls. If you crack up outside of a phone cell you're out of luck, even if you have a secret spare GPS antenna in the rear bumper.
Civilian GPS is accurate to within 2-3 meters, I believe. I'm not sure why MB would settle for 100-meter resolution. Onstar can give me realtime turn-by-turn directions to a restaurant. That can't be done with only 100-meter resolution.
Furthermore, the entire GPS system is not always available. Accuracy can suffer as a result.
The US military can commandeer satellites if there is a need.
If you're within a city, coverage will be sporadic because GPS signals don't travel through things (like brick, mortar, metal, or people) and they don't "bounce." The WAAS can add to GPS accuracy within a city but is not available away from population centers. The WAAS triangulates the GPS signal with a ground-based station whose coordinates are known and fixed.
If driving through the mountains, coverage is sporadic due to nearby hills or mountains, canyon walls, trees, and winding roads that constantly expose you to different sectors of the sky. You can lose a GPS signal when the sky is clearly visible to your eyes.
You may be joking about the slapping steering wheel, but I'm not. There should be a "slap" button in the back seat of every taxicab.
Civilian GPS is accurate to within 2-3 meters, I believe. I'm not sure why MB would settle for 100-meter resolution. Onstar can give me realtime turn-by-turn directions to a restaurant. That can't be done with only 100-meter resolution.
Furthermore, the entire GPS system is not always available. Accuracy can suffer as a result.
The US military can commandeer satellites if there is a need.
If you're within a city, coverage will be sporadic because GPS signals don't travel through things (like brick, mortar, metal, or people) and they don't "bounce." The WAAS can add to GPS accuracy within a city but is not available away from population centers. The WAAS triangulates the GPS signal with a ground-based station whose coordinates are known and fixed.
If driving through the mountains, coverage is sporadic due to nearby hills or mountains, canyon walls, trees, and winding roads that constantly expose you to different sectors of the sky. You can lose a GPS signal when the sky is clearly visible to your eyes.
You may be joking about the slapping steering wheel, but I'm not. There should be a "slap" button in the back seat of every taxicab.
#12
07-24-2004 | 12:43 PM
RE: guess
yes, you're right. the cellphone sends the SOS 
i want to get one of this handy GPS, and get familiar with these stuff.
in your area i think there are at least 5 satellite minimum available at any given time.
i want to get one of this handy GPS, and get familiar with these stuff.
in your area i think there are at least 5 satellite minimum available at any given time.
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