But vanilla GPS just isn't accurate in urban canyons. In London's docklands area (high buildings) GPS gives accuracy in the 200 to 400m region due to multipath effects. As well as obscuring satellites, tall buildings cause reflections of GPS signals which can cause large errors in the pseudo-range calculations making accurate position reporting very difficult. Places like NYC or Chicago are useless for GPS.
I would imagine that supplementing GPS with other position determining mechanisms (like WiFi) could be beneficial in these circumstances.
Slashdot Mirror
Although I agree with the essence of your analysis, you might want to consider:
- a GSM basestation would be potentially transmitting in all 8 timeslots hence the average power would be 8 times higher than a handset;
- GSM/PCN basestation trasmitter powers are quite often about 25W (although I'm not sure whether this is the power after combiners/feeder losses).
But vanilla GPS just isn't accurate in urban canyons. In London's docklands area (high buildings) GPS gives accuracy in the 200 to 400m region due to multipath effects. As well as obscuring satellites, tall buildings cause reflections of GPS signals which can cause large errors in the pseudo-range calculations making accurate position reporting very difficult. Places like NYC or Chicago are useless for GPS.
I would imagine that supplementing GPS with other position determining mechanisms (like WiFi) could be beneficial in these circumstances.