Can shakes run without GPS lock?

Technical Support
1

Hi all,

I recently tried running a shake in an area with alot of tree coverage. I set up the shake to run on stand alone mode, and used the GPS attachment which seemed to have a lock on satellites at the time. Upon returning 4 days later I found there were was a lot of fragmentation in the data and it only recorded for a few hours at a time max. Its worth noting that the shake was also powered by a very long extension cord (~60m), but I couldn’t find anything in the logs that suggested low voltage was an issue. All of the logs and data I have were from downloading them via ssh. Is there something I missed when setting it up? Is there no way of making the shake record data even after losing GPS signal briefly? Please let me know what logs would be necessary to identify the problem or how I can fix this problem. Thanks!

2

Hello chris1928, welcome to our community!

Thank you very much for your detailed description of both the issue and the location the Shake is installed.

Could I ask you to send us the zip file (you can download it from the rs.local/ page or by zipping the entire /opt/log folder) containing all logs?

They’ll help pinpoint the possible cause(s) of the problem you’re having.

Thank you.

3

Thanks for the response! I’ve attached the zip file here.
log.zip (302.8 KB)

Edit: Quick note that the field testing began on April 20th! So April 20th - 24th is the run of data I had issues with

4

No trouble, and thank you for the complete logs from your Shake.

From what I can see, the Shake boots up without issues, but there are some issues, as you can see from this series of errors:

2026 110 15:06:28>>	No Data has been received from the MCU in 12 read attempts.It appears the MCU is not transmitting data.  This is a fatal condition and should be investigated if this condition persists!
2026 110 15:06:28>>	Data has been successfully received, fatal condition resolved.
2026 110 15:06:31>>	internal error: buffer overflow!  cannot process read data...
2026 110 15:06:31>>	buf: {ÿOkøAA@Ma2?ÝÑ?E?AQÐE
2026 110 15:06:31>>	y???U?Z]?ÄL]ª

The gibberish above, paired with buffer overflow and MCU errors, is usually a symptom of insufficient power supply, where the Shake cannot get enough power to either start or work properly.

Thus, in the end, I advise you to check whether the current power supply continues to deliver a stable voltage between 5.0 and 5.2V and a current of at least 2.5A at all times (3.0A if the Raspberry Pi board being used is an RPi4), as a decrease in power could lead to data service interruption.

With your long cable extension situation, and even though you didn’t see low voltage warnings in the logs, voltage drop over long distances can be the cause of what you are seeing:

  • For such a long cable, you’ll need to check if you are getting enough power at its end (and eventually, calculate the wire gauge needed to minimize voltage loss over 60 meters)
  • This is because an insufficient power supply can cause system instability without always triggering undervoltage warnings

Going on to the GPS Signal issues, even though your GPS had a lock initially, tree coverage can cause intermittent loss of satellite connection. Here’s what is likely happening:

  1. If the GPS module loses contact with satellites for too long and then regains connection, it returns to a locked state where the NTP daemon adjusts the computer clock accordingly
  2. This may result in time tears in the data, which, together with the possible power supply issues described above, could explain your fragmentation
  3. These time tears would be noted in /opt/log/odf_SL_plugin.info in this form:
2026 113 04:47:14>>	Time adjustment M0: HARD RESET.  This will result in a one-time time-tear.
2026 113 04:47:16>>	5.0: NTP Time (Init): NTP:	1776919594.253725052
2026 113 04:47:17>>	5.2: NTP Sync (HARD): VEL Before: 1776919470.601999998	After: 1776919593.993000031	Diff: 123.391000032

To summarize:

  • check if you are getting adequate power supply at the Shake, and maybe consider a small UPS that would help in regulating your power situation
  • and then, as you can imagine and if you can, try to improve the GPS antenna positioning as much as possible

Let us know what you find out!