Two bases better than one?

Hi,
I was wondering if adding a second base reach m+ would improve stability of the RTK and get a faster FIX solution.

Your thoughts ?

Nop… RTK doesnt work that way in its current implementation.

It is one of the limitations of L1-only solutions that it has a longer fix-time.

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RTK gets its correction from 1 base. What you are suggesting could be done in post processed kinematic where “maybe” you could get a fix from 1 base if your other base returns a float

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You can use two bases, but not for RTK as Juan said. BUT, if you have a commercial PP software solution you can have a robust way to compute loop closures on short baselines. I do this all the time with local bases on site that are <1 - 2 miles away depending on the project. This ensures that the “fixed” solutions are indeed “fixed” and that you have a closure report accuracy for the loop, i.e. closed polygon .

What software do you use for that ?

GNSS Solutions, TGO (old software no longer is functional due to Trimble’s planned obsolescence),
TBC (Trimble’s new) and JAVAD Justin compute loop closures. You can also use any surveying COGO software to compute the closures from the vector data. I’ve always checked the loop closures and residuals just as a sanity check. I’ve seen too many “fixed” solutions that were not “fixed”. I just bought “Justin” and haven’t had the chance to learn it yet, very steep learning curve just browsing in it. What I like about “Justin” is that it outputs a positional report just like OPUS and also has the computed residuals of the observed vectors like OPUS. This is a good check as well for the accuracy of the baselines. JAVAD also has online processing service using the “JUSTIN” engine just like OPUS but it’s for JAVAD receivers only. Attached is a loop closure report generated in GNSS Solutions from the NGS “St Paul” station I observed on 04/13/20 and posted in another thread. Also attached is the JAVAD DPOS report for a point from another project. Both reports are in “ift” (international feet) units of measurement.

0_ST PAUL 040320.pdf (170.8 KB) 1_122249.jps DPOS 082919.pdf (10.3 KB)

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Starnet, from MicroSurvey, is a good least square adjustment software for survey network. The demo version allows up to 15 GNSS vectors.
They also do FieldGenius for field data collection.

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But pricey AF? :smiley:

if you need more than 15 vectors yes, but there you fall into the land surveyors world. They use to pay a lot for their toys ! :wink:

Is that how they make their pricemodel ? As in if you need less, you pay less?

Yep, all above are very costly but when your in the Professional Land Surveying world, you need what you need. GNSS Solutions was only about $1K when we bought it and I have the latest version, but it’s not being sold anymore. It also has a couple of bugs that you have to be aware of. https://iggps.com/cgo2/index.htm sells CHCNav CGO2 (CHC Geomatics Office Version 2.0) and it’s a very reasonable cost of $620 for PP, it also has the UAV module. I’ll have to check with my accountant to see if we have the funds. I may just buy it myself as another backup PPP in addition to the others I have. It has a fully functional 30 day trial period.

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