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A tip to improve Alpha’s positioning accuracy when doing RTK/PPK with a VRS/CORS source

Read the updated post instead. This post is for an archive.

Some users may find their Alpha has better positioning accuracy when they use it to work with a local (Alpha) base, comparing to working with a public VRS/CORS base.
Here is a tip for those who want to try to improve their Alpha’s positioning accuracy at getting RTK/PPK correction data from VRS/CORS.

  1. RTK scenario
  • Download and run another configuration tool GNSS Viewer. Get Alpha connected with it.

  • Switch to position A (left-hand side) when you are going to config Alpha.

  • Click “Venus 8 ->Configure GNSS Constellation Type”

  • Check “GPS” ONLY.


    This helps in some VRS/CORS cases because the Glonass signals provided by the VRS/CORS may not include a specific field needed by Alpha to calculate coordinates. In this case, omitting bad Glonass signals and using only GPS signals helps accuracy improvement.
    By choosing “Update to SRAM+FLASH”, you can configure Alpha to remember the setting of using only GPS signals at next boot, in the case you are always working with VRS/CORS.

  • Switch to position B (right-hand side) when you are going to use Alpha as a ROVER. Keep it at position A if you are going to use Alpha as a ROVER.

  1. PPK scenario

Let me know if this helps in your exploration with Alpha.

image
Hi Jim!
Did as your guide.
Result: Alpha RTK is used with unstable public CORS source.
Very long measurement time was tested but still unstable (Float RTK). Fix RTK is very short and inaccurate.
Can you find out the cause?
Look forward to you and Polaris interest.





Best regards!
Thank you.
Mr Tinh.

Hi Mr. Tinh,
If your CORS provides BeiDou signals, you should enable GPS and BeiDou signals. We found Glonass has this issue while BeiDou does not; you can try to enable it.
Please let me know if it helps.

This issue should be closed by the newly released firmware mentioned in the above thread. Please update your Alpha+ soon.