Is my GPS working?

We purchased a USB GPS when we got the JAM, but I can’t tell if it’s getting signal. Is there any log file or query to check? From the command line, timing appears to be from the local NTP server:

myshake@raspberryshake:/opt $ ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
*dorset.ldeo.col     3 u 1036 1024  377    0.772    0.066   0.259
 SHM(0)          .GPS.            0 l    -   16    0    0.000    0.000   0.000
 SHM(1)          .PPS.            0 l    -   16    0    0.000    0.000   0.000

It is not reading anything from the GPS.

The reach of 377 you see for dorset.ldeo.col means that NTP found the last eight times good from there.

The reach number for the NEMA time string (SHM(0)) and pulse per second (SHM(1)) are both zero. This means it found nothing acceptable in the last eight attempts for both of them.

As for logging, you could turn that on in /etc/ntp.conf; but I don’t believe you would gain more information. What do you see in the file /opt/log/gpsd-mgr.log?

In the /opt/log/gpsd-mgr.log file, a successful connection to a GPS module looks like this:

========== TEST BEGIN ==========
2019 269 11:17:27

========== TEST END ==========

A failure looks like this

========== TEST BEGIN ==========
2019 259 23:00:45

No device named /dev/ttyUSB* found, dongle appears to be not plugged in.

========== TEST END ==========

And if the GPS solution is good and being used, your ntpq -pw will look like the following:

$ ntpq -pw
     remote           refid      st t when poll reach   delay   offset  jitter
 SHM(0)          .GPS.            0 l    7   16  377    0.000  362.949   3.486
*SHM(1)          .PPS.            0 l    8   16  377    0.000   -0.226   0.405   2 u   47   64  377  102.003    8.731   3.429   .XFAC.          16 u    - 1024    0    0.000    0.000   0.000
           2 u   53   64  377  105.166    7.404   3.573


This is definitely the latter (dongle appears to be not plugged in,
though it definitely is). If I switch USB ports, will it attempt to
find it, or do I have to reboot each time?


Hi Mitch,

Can you send the logs from the web front end?



Here are the logs. I’m not sure what’s up with the USB bus, it was working last week when I was using a keyboard to login.


RSH.R4920.2019-10-09T18_01_03.logs.tar (1.04 MB)

Hi Mitch, from your logs it looks to me like your SD card is corrupted. My guess is that re-burning the OS will solve this issue, although your SD may also be nearing the end of its life. The image and instructions for copying the OS to the card are here:

If you do end up buying a new card I recommend one of two:


Buenas tardes.

Our records indicate that Won-Young Kim did not get the microSD card from us.

Please see here before buying your next microSD card:

Kind regards from Panama, branden