Re: [gpsd-users] Python GPSD interface and symmetricon 2750

[Gary E. Miller]

Yo Ryan!

On Sat, 14 Apr 2018 14:20:02 +0000
Ryan Tennill <address@hidden> wrote:

> For some reason the python interface doesn't seem to be picking up the
> number of satellites or the fix status.

Which Python client?  gpsd does not get the number of sats from the
fix status, it gets that from GPGSV.

> I am parsing the responses
> myself to work around this behavior

So you see good JSON from gpsd?  Just no "SKY" JSON?  No GPGSV, then
no "SKY".

> but I would like to use more
> tried and tested machinery in gpsd if it's available.

It should be there, or it will get fixed.

> I assume I just
> don't have it configured correctly.

gpsd intentionally has few knobs.  It is meant to "just work".  Or
do you mean your client?

> The GPS is configured to send GGA and RMC messages over the serial
> interface which seems to be working just fine. I get good data when
> watching gpspipe and gpsmon does show the proper fix status and
> satellite count.

A good sign.  Remember that when gpsd starts it also does some
reconfiguring.  Unless you use the gpsd -b option to stop that.  But
-b is not totally effective.

> Here's what the client looks like after receiving some GGA and RMC
> messages:
> 
> Time:     2018-04-13T14:21:15.000Z (2018-04-13T14:21:15.000Z)
> Lat/Lon:  40.116415 -88.311605
> Altitude: 227.000000
> Speed:    0.000000
> Track:    0.000000
> Status:   STATUS_NO_FIX
> Mode:     MODE_3D
> Quality:  0 p=0.00 h=0.00 v=0.00 t=0.00 g=0.00
> Y: 0 satellites in view:
> 
> 
> Some example sentences are:
> 
> '$GPRMC,142115.00,A,4006.9849,N,08818.6963,W,0.0,0.0,130418,,*21\r\n'
> '$GPGGA,142116.00,4006.9849,N,08818.6963,W,2,10,0.9,227.0,M,-33.2,M,,*51\r\n'

No sat data in there.  You need GPGSV to get the sat data.

No DOP data in there.  For that you need GPGSA.

> Datasheet: https://www.microsemi.com/existing-parts/parts/138158
> Setup: GPS-2750 over UART (not USB-Serial) to a Nvidia Jetson TX2
> running Ubuntu 16.04 (arm64)
> GPSD version: 3.15 (revision 3.15-2build1)
> Watch flags: WATCH_ENABLE|WATCH_JSON|WATCH_RAW


Nice little board.  15 ns PPS acccuracy is nice, but not exactly what I
would call "atomic accuracy".

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin

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