[ntp:questions] time delta between clients

David J Taylor david-taylor at blueyonder.not-this-bit.nor-this-bit.co.uk
Thu Dec 13 07:55:44 UTC 2007


Rick Jones wrote:
[]
> I suppose I could also try to see if I can get the powers that be to
> spring for a GPS18 and see if I can indeed get signal in the machine
> room(s) of interest.
>
> Speaking of which, I was just at the garmin website, and seems they
> now have a GPS18 5HZ in addition to the regular GPS18.  Is there any
> benefit to the extra four pulses per second?
>
> rick jones

Rick,

I have found that, compared to recent GPS receivers, the GPS-18 is not 
very sensitive.  For example, I needed to mount the unit outside my 
window:

  http://www.david-taylor.myby.co.uk/ntp/FreeBSD-GPS-PPS.htm

facing south, to get any signal, whereas my GPSmap 60CSx works fine 
/inside/ the same room.  Even outside the window, the approximately 
180-degree sky view resulted in some loss of sync, and I now have the 
GPS-18 on the roof which has a 30 degree slope to the west.  Not ideal, 
but better than before.

There is no advantage to the 5Hz unit with the present NTP implementation.

Cheers,
David 





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