[time-nuts] GPS W/10KHz

Dennis Ferguson dennis.c.ferguson at gmail.com
Mon Feb 10 16:52:39 EST 2014

On 10 Feb, 2014, at 00:48 , Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
> Instead of speculating try reading the specifications.
> 1Hz phase modulation of the 10kHz output is present.
> The receiver sawtooth error sample rate is 1Hz not 10kHz.
> The 10kHz output signal phase is adjusted at a 1Hz rate by the receiver.

Ah, as soon as I pressed send for the last note I realized what
you were likely telling me.

Yes, the LEA-6T only provides you with a quantization (sawtooth)
correction for 1 pps and no higher rate.  At 1 pps you should
pay attention to the digital correction (implying no analog-only
implementation is possible; you minimally need the delay line
thing) since the frequency of the saw tooth is often low enough
to leak into the control response and the correction should make
the sawtooth go away.

All I was pointing out is that at a higher output frequency, like
10 kpps, the frequency of the quantization saw tooth error will
almost always be much higher as well.  There's no need for the digital
correction since averaging over a relatively short period, like in
the loop filter of an appropriate analog PLL, will almost always be
sufficient to smooth the sawtooth.

Dennis Ferguson

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