GPS coordinates shift after reboot of base station (RTK Surveyor kit)

Kits
1

Good day and sorry for asking this question - It might be too basic, but I cannot find any good explanation to it.

We bought a SparkFun RTK Surveyor kit a few years ago - when it was just released.

The kit contains a:

  • Base station

  • Rover

The Rover unit is located on an Autonomous Solar Powered Tractor that is helping us at our farm.

We’ve been using it for 3 years now and take the GPS coordinates from the Rover unit to a Raspberry Pi that is controlling the tractor.

Over the years we’ve setup several paths for the tractor to follow and it’s been working great.

This year we however had to re-boot the Base station unit a month ago (plenty of time for it to settle), and when we started the tractor last week it seems all the paths had shifted. We now have an offset of about 0.6 meters when we try to follow stored GPS coordinates - but the Rover claims to have RTK accuracy.

To the question:

  1. Can the correction signal from the Base station change after a reboot (even if we let it settle for a very long time)? (It’s still located at the same place)

  2. If we read a GPS coordinate from the Rover, and later move the base station (and let it settle), should we be able to end up at the same spot by following the GPS coordinates?

  3. Is there an easy way to see, store and interpret the correction data? (reading it of the GPS to a Raspberry Pi)

Your input is MUCH(!) appreciated.

Sincerely,

Rasmus

2

  1. It depends…it wouldn’t move much if the base’s measurements were validated https://docs.sparkfun.com/SparkFun_RTK_ … ification/ and it is a permanent base (with relevant antenna offsets input and whatnot) https://docs.sparkfun.com/SparkFun_RTK_ … nent_base/

  2. See this as well https://learn.sparkfun.com/tutorials/ho … -gnss-data (this guide is very similar to the above). You should be able to perform the verification steps after a reset and then resolve any deviations on the data processing side of things

  3. Another user created this handy setup guide https://github.com/jacobjhansen/RTCM-Pi that should help you get started

3

Thank you very much for your input - highly appreciate it!

I’ll roll up the sleaves, go though the guides and revert after the weekend.

4

As a short feedback:

We changed the antenna of the base station to a bigger one, but the issue remained.

In the end we implemented local correction on the incoming GPS value to last years reference point.