General > General Technical Chat
Does anyone play with GPS based ntp server and have clients?
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tkamiya:
Thank you.  I didn't even think of that.
tkamiya:
With my previous setup, both GPS and PPS would go to "X" state.  Often times immediately, sometimes an hour or so later.

So, I made several changes. 
1) replaced GPS
2) shorten the pps and data serial cable
3) play with offset a little

12 hours later, I got this:
     remote           refid      st t when poll reach   delay   offset  jitter
===================================================

*SHM(0)          .GPS.            0 l    1   16  377    0.000   -9.225   5.857
oPPS(0)          .PPS.            0 l   15   16  377    0.000    0.000   0.001
<more sources here>

This is how it should be, correcct?
ve7xen:

--- Quote from: tkamiya on December 14, 2021, 03:47:09 pm ---With my previous setup, both GPS and PPS would go to "X" state.  Often times immediately, sometimes an hour or so later.

So, I made several changes. 
1) replaced GPS
2) shorten the pps and data serial cable
3) play with offset a little

12 hours later, I got this:
     remote           refid      st t when poll reach   delay   offset  jitter
===================================================

*SHM(0)          .GPS.            0 l    1   16  377    0.000   -9.225   5.857
oPPS(0)          .PPS.            0 l   15   16  377    0.000    0.000   0.001
<more sources here>

This is how it should be, correcct?

--- End quote ---

Looks fine, assuming the offset to your other sources is reasonable and ntpd hasn't marked them all invalid because they don't agree with your prefer source.
tkamiya:
Offset used for GPS (local)

server 127.127.28.0 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.0 time1 0.032 flag1 1 refid GPS

fudge will require further tuning.

none of other sources are "X"'d out. 
jav:
Looks great.

Don't bother too much with the GPS offset (and the fudge factor). As long as it's around those levels, it's fine. ntpd will use PPS as a reference, that's what is for.

Key here is that the values keep in that range so ntpd don't falsetick ("x") them out.
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