XPost: comp.os.linux.misc   
   From: bowman@montana.com   
      
   On Sun, 14 Dec 2025 23:06:26 +1100, Daniel70 wrote:   
      
   > And your GPS Speed is only indicating what you were doing, what, 0.5   
   > Secs ago .... cause the signal has to go up to the Satellite and come   
   > back down, doesn't it??   
      
   No. The GPS receiver calculates your position from a number of satellites.   
   The more satellites in the constellation it can 'see' the better the fix.   
   Ideally there are some close to the horizon rather than clustered   
   overhead.   
      
   The speed is calculated by the distance covered in the time between two   
   readings. My fitness tracker records a position every second which is   
   sufficient for most activities including bicycling.   
      
   At times my top speed is erroneous, say 4.5 mph (I'm not a runner). Given   
   the margin of error and perhaps problems with trees etc you can get two   
   recorded points that are farther apart that the distance over the ground.   
      
   The GPS in the car is usually reliable but there are some places where the   
   speed is obviously off and the location may be displayed off the road. I   
   don't know how frequently the Nuvi acquires a position. It may be more   
   frequently than the tracker which makes the trade between accuracy and   
   battery life.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)