[time-nuts] OT - GPS and North

[Magnus Danielson]

Bob Camp wrote:
> Hi
> 
> If you only have one antenna and one receiver, the answer is fairly simple. Swing it around you head on the end of a long string. Plot the position reading vs time. Correlate the readings to the phase of the rotation. 
> 
> It does indeed work (it's a doppler scanner ...). You could easily argue that it's not exactly a stationary situation any more. 
> 
> Making it work correctly would involve a lot of work figuring out just how much lag the receiver has. You might have to swing it at a 10 rpm rate ...

Putting it on a constantly rotating platform would work too. I actually 
made a comment about moving the antenna as an alternative to the use of 
multiple antennas. You can use the velocity vector in correlation with 
the local rotation indication to transform the local reference frame to 
that of the direction to north. Just swinging it around is pretty 
useless unless you bring that in correlation to that local reference 
frame. Also, you would like a fairly stable swingrate so that 
correlation becomes easier. Also, having a higher rate receiver, such as 
10 or 20 Hz would also be nice. The PPS is a suitable reference pulse to 
correlate angle-measurements with that of the position given.

Cheers,
Magnus