Re: GPS/PPM very large offset

[Mike Simpson]

Hi B&A and Gary. 

It’s glonass 
They run such a big offset that they are unusable for time. 

ubxtool -d GLONASS

Need to do this every time after Pi reboot or presumably cold restart of the 
GPS. 


Mike 

> On 6 Nov 2020, at 19:46, Gary E. Miller <gem@rellim.com> wrote:
> 
> Yo B&A!
> 
>> On Fri, 6 Nov 2020 20:24:52 +0100
>> B&A Consultants <infos+gpsd@ba-consultants.fr> wrote:
>> 
>> Hello Garry,
> 
> One 'r'.
> 
>>> On 06/11/2020 19:46, Gary E. Miller wrote:
>>> We need some of you implementation details to take a guess here:
>>>         gpsd version  
>> gpsd 3.21
> 
> Good.
> 
>>>         gpsd command line  
>> Started through openrc.
>> /usr/sbin/gpsd -n -r -F /run/gpsd.sock -P /run/gpsd.pid /dev/ttyAMA0
> 
> Usually you do -F for hotplug.  You doing any hotplugging?  But not
> really a problem.
> 
>>>         ntp.conf  
>> We are using ntpsec, but we can switch to ntp if it makes things
>> easier to pinpoint the problem.
> 
> You realize gpsd is also the NTPsec team?
> 
>> # GPS PPS reference (NTP1)
>> refclock shm unit 1 refid PPS
> 
> Missing "prefer", but not your problem.
> 
>> # GPS Serial data reference (NTP0)
>> refclock shm unit 0 refid GPS
> 
> Missing "ignore", but not your problem.
> 
>>> Does cgps show a valid 2d fix?  For how long?
>>> How many leap seconds does cgps show?  
>> 
>> Here is an example of cgps display.
>> 
>> │ Time:        2020-11-06T19:15:58.000Z (18)│
>                                          ^^^^
> 
> You have the correct leap seconds; 18.
> 
> So no idea where your 5 seconds is coming from.
> 
>> │ Latitude:         somewhere N             │
>> │ Longitude:        somewhere E             │
> 
> You think we don't know you are near Compiegne, Berck-Plage,
> Allonne and Poissy?  About 49N, 2E.
> 
>> Do not know if it may be useful, but the Alt (HAE, MSL) line
>> oscillates betwene some values and n/a.
> 
> Yup, that is what your GPS is sending to gpsd, gpsd just repeats it.
> The joys of NMEA.  Depending on your receiver you can fix that.  For
> u-blox go into binary mode.
> 
> What is your GPS model, and how is it configured?
> 
> RGDS
> GARY
> ---------------------------------------------------------------------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>    gem@rellim.com  Tel:+1 541 382 8588
> 
>        Veritas liberabit vos. -- Quid est veritas?
>    "If you can't measure it, you can't improve it." - Lord Kelvin