Inside GPS really won't work. At the frequencies GPS uses the attenuation by the buildings will be significant and you probably won't get a lock. Also, any "bouncing" or propagation of the GPS signals will increase the time they take to reach the receiver thus causing error in the positon the GPS unit calculates. GPS satellites themselves do not track anyone. They send out identifiable signals along with a very accurate time signal and the satellite's current postion. The signals from 3 or more satellites are received by a GPS unit, then the GPS unit, using the encoded time signal, the sat's known postion, then figures out how long it took for the signal to hit the GPS unit. It then triangulates this into postion information... the same way a sea faring navagator would "shoot the starts" with a sextant and a book of star positions and triangulate his position. If the signals to a cell phone in the tube, took a few bounces before hitting the cell phone... you would never notice the propagtion delay. In GPS, the propagation delays would result in errors to great for your (or most any) application. Bill KA8VIT *********** REPLY SEPARATOR *********** On 2/10/2004 at 7:23 PM Stan Wijnans wrote: >This might be the wrong list, but I thought I try as I think somebody >might know ! > >I am interested in developing a GPS tracking system to trigger people >for an art project. I'm trying to find out if this is possible inside a >building as I am aware that GPS tracking has already been developed for >outside but seems to be weak inside ... > >Does anybody know how to make the GPS sensitive enough to go through >walls, do I need a differential GPS or has anybody suggestions ? I have >seen people on mobile phones in the tube in Asia, so something should >be possible .... but how :-)) ?? > >Any help is much appreciated >Thanks, Stan ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Tue Feb 10 2004 - 14:50:29 EST