[time-nuts] Raspberry Pi NTP server

[Steve Platt]

On 03/07/2020 13:56, Andrew Hancock wrote:
> But here's the weird thing, it starts out okay, from what I can tell, and I get 377 for both GPSD and PPS
>
>       remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *127.127.28.0    .GPSD.           1 l   21   32   37    0.000   98.447  89.508
> o127.127.22.0    .PPS.            0 l   20   32   17    0.000  -63.468  27.800

That's NOT ok, IMHO :-)

I think the offset and jitter for the PPS server are far too high. 
Here's what my Raspberry Pi2 looks like:

> $ ntpq -p
>      remote           refid      st t when poll reach   delay offset  
> jitter
> ==============================================================================
> *SHM(0)          .SHM.            0 l    7   16  377    0.000 -90.737  
> 65.556
> oPPS(0)           .PPS.             0 l    5   16  377 0.000    
> 0.002   0.002
> +ntp0... (other NTP servers omitted but 0ffset values were 1 or 2 ms)

My setup sounds like your original, with a GPS Hat and PPS on a GPIO 
line.  The huge difference between your remote servers and your PPS 
signal suggest (as others have said) that the timing of your PPS signal 
is wrong.  I think that is the cause of your problems.

Steve