Troubleshooting Assistance

Hello everyone,

We have an issue where I cannot figure out how to troubleshoot or where to look to try and find the source of the issue(s).

We have 2 sets of pickups Day 1 and Day 2. Day 1 and Day 2 had the base setup over a different location. We typically lay a point out near/next to the base location to do some sanity checks, and we also pick up the point as the first point, and also the last point of the day. We always convert these to a UTM system.

On day 2, we also re-picked up 3 points from Day 1 to tie into and check against (we will call them A1,A2, B1, B2, C1, C2)This is where the troubles come in…

Day 1 and Day 2, the first and last point of the respective day line up within a couple of mm yay!

I am making the assumption that Day 1 is the one that I want to be the “truth” and Day 2 is the one that we want to adjust to line up with Day 1. I extract the 3 point from Day 1 and Day 2 to do a comparison against. Normally, when I do a different between all of the, the average of the difference is pretty good.

i.e. normally it looks something like this:

Northing: Easting: Elevation:
A1 - A1 = 0.456 A1 - A2 = 1.060 A1 - A2 = 2.560
B1 - B2 = 0.487 B1 - B2 = 1.070 B1 - B2 = 2.530
C1 - C2 = 0.446 C1 - C2 = 1.050 B1 - B2 = 2.550

So it is all pretty tight, consistent and I can easily do the adjustments and away we go. But this time, I got some pretty wacky numbers. More like this:

Northing: Easting: Elevation:
A1 - A1 = 0.326 A1 - A2 = 0.956 A1 - A2 = 1.560
B1 - B2 = 0.887 B1 - B2 = 0.070 B1 - B2 = 0.530
C1 - C2 = 0.946 C1 - C2 = 0.578 B1 - B2 = 0.250

I have also tried to post process to see if any of the results are different, the following are the main things I have tried:
Processing forwards, backwards, combined
Base station with position in header, average single position.

So, if you got these sorts of results, where would you start to look?

Let’s start with all the basic questions first, so they are covered:

  • What does Your environment look like?
  • What was Your PDOP like (for both base and rover)? Similar on both days?
  • With your short baseline (without knowing the exact length?), have you tried processing as L1 only ?
  • Would it be possible to have You upload base and rover raw files?

Hey @wizprod

  • RS+
  • Environment is in a swamp/lagoon area
  • Baselines are within 1.2km (of each other and furthest points)
  • L1 only processing, and also tried adding in other constellations during PPK

Here are the log files for both days in RINEX 3.03 format and the survey csv:

When/if you look at satellite images of the area, it paints a much greener image than it is. This area has been in severe drought for the last 7 to 8 years and not much in the way of trees of any description (or water for that matter).

And here is a quick look at it all in UTM:
Tie in (19.5 KB)

Hi Ashley,

May I ask you to share your position log files as well?

Also, could you please advise if I understand correctly that you averaged the base position before each of these 2 surveys?

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