GCP's using two RS2s, ppk for Base

I just received two reach RS2 units. I intend on using them in a base/rover setup to establish GCPs. I do not have a subscription to a NTRIP service, and won’t be able to get one. I do however have continuously operating reference stations nearby, I can download logs from them.

It seems to me that there are two ways I could do this. Looking for advice about which way makes more sense and is easier.

  1. In the field I could let the base establish its own position using single, average. Then use LoRa RTK between my local base and rover and use “survey” to collect the points. Back at the office, I can use RTKpost with the CORS and my local base to get a more accurate position for the base. Then, compare the offset from the field-established “base” position and the ppk-established “base” position, and correct all my collected points with that same offset.

  2. In the field I can just collect logs from the base and rover, use “survey” just as a way of timestamping when i’m collecting points, then use RTKpost to first establish the accurate position for my local base off of the CORS, and then secondly to establish an accurate track for my rover against my local base. Then, figure out my collected GCP locations from the rover log using the known collection times from the “survey” file.

Which one makes more sense and would be easier? I got thinking about option 1) by reading the following statement in the reach documentation (tutorials: basics: placing the base: post processed kinematics) " * After you get the coordinates you may enter them manually in Base coordinates section. Comparing PPK position to the averaged position and applying corrections to the collected data is the way to compensate the shift shown in the example on figure 2 ."


Yep either way… I don’t use the app except for static with my M2’s, usually if I’m in the field and have no RTN. I just log base and RTK my points off the base. I’ve got all Javad gear with my M2’S for static.

After the field, I’ll PP the base and translate all the RTK points (horizontal/vertical) to the new PP base.

Others here are more familiar with the app, they will offer advice too

I was leaning that way. May I ask, what method do you use to translate the points? Arcmap, excel, some other tool?

Carlson software, we’ve been using for decades as it’s designed for surveyors/engineers.


First off, I assume you need the absolute accuracy from how you write your post.

Your first option will definitely be the easiest. But you would have to trust your RTK derived data completely!

I like the second option much more… especially if you also do number 1, and compare the 2 results as a blunder detection.


Absolute accuracy is important for us. Yes, I agree approach 2) seems like a more robust approach. For training purposes I will do what you suggested and do both and compare.

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Same here for 20 years. Survey, Civil and Precision 3D!

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Let’s us know how it goes!

Hi Derek,

Both methods allow you to get precise GCPs’ coordinates. As Christian said, the first one is easier, as you don’t need to record collection time for each point and extract the points manually from a continuous log.

As an alternative, you can get the base position using the PPP technique. It requires at least 4 hours of logging, but after you get the base coordinates, you can collect GCPs without a need to apply an offset.

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Do you have ANY monumentation within GPS range of the site? If so couldn’t you occupy that with you base and RTK in a couple of points. We have done this many times when there was not enough site control to localize to. I would suggest at least two so that you have a “backsight” once you occupy one of them as your new base. Three would be better, but not a necessity.

The only problem for us was that what we brought in was true grid coordinates and the design files had surface coordinates that did not exactly line up, but we were able to translate them in Civil 3D pretty easily.


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