Re: [gpsd-users] NTP1 keeps going away.

[stinga]

On 09/11/17 11:50, stinga wrote:

On 09/11/17 08:50, David J Taylor wrote:

From: stinga

address@hidden:~# ppstest /dev/pps0
trying PPS source "/dev/pps0"
found PPS source "/dev/pps0"
ok, found 1 source(s), now start fetching data...
source 0 - assert 1510148557.996485612, sequence: 438970 - clear 0.000000000, sequence: 0
source 0 - assert 1510148558.001389037, sequence: 438974 - clear 0.000000000, sequence: 0
source 0 - assert 1510148558.001719066, sequence: 438985 - clear 0.000000000, sequence: 0
source 0 - assert 1510148558.015093227, sequence: 438986 - clear 0.000000000, sequence: 0
source 0 - assert 1510148558.020151666, sequence: 438998 - clear 0.000000000, sequence: 0
source 0 - assert 1510148558.996611407, sequence: 439003 - clear 0.000000000, sequence: 0
source 0 - assert 1510148559.001163803, sequence: 439006 - clear 0.000000000, sequence: 0

It is strange , as it just sits there quite happily and then eventually barfs and looses NTP1.
===============================

I would check the PPS signal with an oscilloscope - it seems to have some "bounce" so may not be very "clean".  The GPS isn't set to 5 iterations per second, I suppose?

Hi David,

Thanks for the response, I don't believe it is set for 5 per second and I have just seen one with 21 iterations.

I don't have access to an oscilloscope currently, but I can get one.
If the PPS is not clean what can I do to fix this and what could cause a non-clean signal?

Replying to my own post....

I have now rebooted (in error) and I am not getting any PPS signal now :-(

I also note from page http://www.catb.org/gpsd/installation.html

You can verify gpsd is using the PPS by running ntpshmmon:

~ # ntpshmmon
#      Name   Seen@                Clock                Real               L Prec
sample NTP0 1461619703.641899335 1461619703.445224418 1461619703.000000000 0  -1
sample NTP2 1461619703.642203397 1461619702.999262204 1461619703.000000000 0 -20
sample NTP0 1461619704.142097363 1461619703.445224418 1461619703.000000000 0  -1
sample NTP2 1461619704.142204134 1461619703.999258157 1461619704.000000000 0 -20

If you do not see NTP2 then you misconfigured the pps_gpio driver.

The serial time is provided to ntpd on NTP0, the PPS time is on NTP2, not on NTP1 like described earlier. So your ntp.conf will need to be adjusted from:

So, should I see NTP1 or NTP2? I have seen NTP2 on occasions.

-- 
'ooroo

Stinga...(:)-)
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