Re: gpsd g10de777bb vs Jackson Labs Micro JLT

[Daniel O'Connor]

> On 12 Aug 2021, at 10:40, Gary E. Miller <gem@rellim.com> wrote:
> 
> Yo Daniel!
> 
> On Thu, 12 Aug 2021 10:02:48 +0930
> "Daniel O'Connor" <darius@dons.net.au> wrote:
> 
>> We recently got a Jackson Labs Micro JLT at work (to attempt to
>> replace a PRS-10 Rubidium standard for bistatic radar operation) and
>> I thought I'd try feeding its output to gpsd.
> 
> I'd be interested in the detailed comparison.
> 
> Cool.  What version gpsd?  From where?

As per the subject, g10de777bb (I cloned it fresh yesterday)

> Version 3.23 is out now.  
> 
> Versions 3.20 to #.22 will fail on 23 October 2021.
> 
>> Mostly it seems to work, however I was getting log messages like so:
>> gpsd:WARN: cycle-start detector failed.
>> gpsd:INFO: Sats used (0):
> 
> Yes, normal.
> 
>> .. until I enabled GSA messages.
> 
> Yes, normal.

OK, perhaps a FAQ entry about what it means would be useful then.

>> One final problem is that it doesn't seem to parse the GSV messages
>> correctly.
>> 
>> If I run 'gpspipe -r --pps' I see (plus my manual parsing of SVs):
> 
> You realize the -r maybe psuedo-NMEA?  Nor real NMEA.  I really need the
> "superraw" from "-R" to see what is happening.
> 
>> $PJLTS,0.28,1.48,68218,6,2.5828650,86.0955,1.1E-12,0,16,0x0*5E
> 
> Got any doc you can share on that one?

It's documented in the MicroJLT user manual:
http://www.jackson-labs.com/assets/uploads/main/Micro-JLT_User_Manual_v1.2.pdf

It is head line stats about the clock management/health.

>> However cgps shows..
> 
> I'm guessing the GA201, which would be an illegal gnssid:svid combination
> is what you want us to see?
> 
> No idea on that.  To debug I need the output of:
> 
>        gpspipe -R -x 20 > raw.log

OK attached.

>> The MicroJLT has a ublox M8T so I assume it uses the same PRN
>> numbering.
> 
> "same" as what? u-blox, and NMEA 0183, documents many inconsistent PRN
> numbering schemes that are user selectable.

Given it was gpsd mangling them I guess this isn't relevant anyway.
The raw output shows GPGSV and GAGSVs.

> Newr gpsd prefers the newer gnssId:svId:sigId scheme.

raw.log
Description: Binary data

--
Daniel O'Connor
"The nice thing about standards is that there
are so many of them to choose from."
 -- Andrew Tanenbaum