Find out Base Fix locations


My client (a novice at using Emlid) recently conducted a survey where he used Emlid Reach RS to collect points, in a base + rover configuration. Around 70 points were collected. However, I found out that at various points in time during the survey, he restarted the base. The base fix method was a 2 minute observation. He just sent me the set of GeoJSONs taken from the ReachView app. I’m not sure what the base position was when the 70 points were logged (I only know that the basefix was constant for a given GeoJSON set). I know that the base was not physically shifted throughout the process (it was only restarted). I therefore need to shift the points to the common base point (which will be different for each reset cycle).

How do I find out what the base fix position was for each GeoJSON (i.e. for each survey)? I have asked my client to send me the UBX, RTCM and LLH logs for both the base and the rover. However, I do not want to do full PPK - I just need to know the base fix position that the rover was seeing at each point of time. How do I do this?



Hm, that’s a tough and unfortunate one.

I don’t see a way around PPK’ing this. Using some of the stop-and-go tools available here (that loads the .csv file and crosses it with the .pos file), it shouldn’t that time consuming.

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You didn’t explain why the base was restarted. If the survey was done in 3 parts, then maybe the rover was restarted as well. If you have 3 .POS files on the rover, then maybe you can see the base position in the header of each .POS file like this:

% ref pos : 10.3938484 20.222828282 300.2020

That is probably the easiest way to get the info you are looking for. (Also, I’m not claiming that the ref position there is actually correct for this situation, but it might be.)

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It should be in the RTCM data: 1005 or 1006. I do not know good way to decode RTCM and make legible for human.

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