running without pool or other servers

[shouldbe q931]

Apologies for the delay in replying, gmail decided to file you as spam...

On Mon, Sep 11, 2017 at 9:11 PM, Gary E. Miller <gem at rellim.com> wrote:
> Yo shouldbe!
>
> On Mon, 11 Sep 2017 15:17:37 +0100
> shouldbe q931 <shouldbeq931 at gmail.com> wrote:
>
>> I am attempting to run ntpsec in a "standalone" instance where it is
>> only provided time and PPS from a GPS receiver (via gpsd).
>>
>> The relevant lines in ntp.conf I have arrived at are
>>
>> # GPS PPS reference (NTP1)
>> refclock shm unit 1 refid PPS minpoll 0 maxpoll 0
>>
>> # GPS Serial data reference (NTP0)
>> refclock shm unit 0 prefer minpoll 4 maxpoll 4 time1 +0.118 stratum 1
>> refid GPS flag1 1
>
> You are missing prefer on SHM(1).  Otherwise ntpd does not know to prefer
> the PPS over the NMEA time.  Some would also add noselect to SHM(0).

If I add prefer to the PPS line and noselect to the GPS line, then
ntpq shows that the PPS line is the system peer, but from the ntp.conf
page the GPS line is only used for display, which as I understand it
would then mean I would need something else to set the system time,
which would defeat the purpose of running in autonomous mode...

With only the prefer on PPS and without the noselect on GPS I did not
see either change from x

I have also tried using the server instead of refclock lines and
adding true to the PPS and prefer to the GPS

# GPS PPS reference (NTP1)
server 127.127.22.0 minpoll 0 maxpoll 0 true
fudge 127.127.22.0 refid PPS

# GPS Serial data reference (NTP0)
server 127.127.28.0 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.0 time1 +0.118 flag1 1 refid GPS stratum 1

This changes (takes several minutes) between x & o for PPS and x, +, &
* for GPS.  I haven't seen a log message that corresponds with the
change as seen by ntpq to be able to provide an accurate time.

I had tried the what I understand to be the functional equivalent

# GPS PPS reference (NTP1)
refclock shm unit 1 refid PPS minpoll 0 maxpoll 0 true

# GPS Serial data reference (NTP0)
refclock shm unit 0 minpoll 4 maxpoll 4 time1 +0.118 stratum 1 refid
GPS flag1 1 prefer

but it would appear that the "true" will only work on a server line

To my untutored eye the server & fudge lines have been the most
promising in that it shows the PPS as a PPS source, but then still
rejects both as false tickers.

I know I'm not looking for a left handed screwdriver, but I am
starting to wonder if I'm looking for a wild goose (-:

Cheers