[time-nuts] How to measure Allan Deviation?

John Ackermann N8UR jra at febo.com
Sun Oct 22 21:17:20 EDT 2006


Dr Bruce Griffiths said the following on 10/22/2006 08:24 PM:

> Reading between the lines on the Jupiter GPS receiver datasheet it would 
> appear that the 10KHz output is phase modulated at 1Hz to realign it to 
> successive PPS output pulses. As the PPS jitters about so does the 10KHz 
> signal.
> Most GPS receivers with higher frequency outputs than 1Hz, phase 
> modulate the high frequency output in this way and the datasheets 
> explicitly indicate this.
> 
> Thus there would appear to be little advantage in phase locking to the 
> 10KHz signal with a short loop time constant.

Hi Bruce --

I believe you're correct that the 10kHz output jitter is not any better
than the 1 PPS jitter; there's been some confusion about that in some of
the projects that use the Jupiter receivers.

John



More information about the time-nuts mailing list