[time-nuts] What's the time Mr Wolf...

[Björn Gabrielsson]

On Mon, 2008-11-03 at 00:21 -0800, Hal Murray wrote:
> > So everything is derived from this oscillator, which is actually
> > 10.22999999543 MHz. This -4.57 mHz corrects for relativistic
> effects. 
> 
> Neat.  Thanks.
> 
> I got curious.  How does that compare to the Doppler shifts?
> 
> google found this nice description of GPS :
>   http://www.go.ednet.ns.ca/~larry/gps/gps_talk.html
> 
> It says the Doppler shift is up to 2400 HZ.
> 
> That's a half-million times the relativistic correction.

There is also about 1 kHz frequency uncertainty from the crystal driving
the GPS receiver. As most receivers use oscillators specified at about
0.5ppm.

btw... I once heard a story that early GPS SVs could turn off the
relativistic compensation. There was also a switch to reverse the
sign... ;-)

--

    Björn