Should have read... would "shoot the stars" with a sextant and... Bill KA8VIT *********** REPLY SEPARATOR *********** On 2/10/2004 at 2:38 PM HSHK wrote: >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 ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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