RMS at FLOAT solution with RTK

Hi everyone,

I have a system RTK Reach RS+, sometimes I have problems with the trust of RMS at float solution, for example the RMS at a know position say 10 cm, but the real error is more of one meter, I know that float solution which is less statistitly trustworthy that a fix solution, but is too much the difference. Maybe there are others factors unknowlege, because I define the configuration the solution float until 50 cm, not more. There is some one that can help me with a suggestion…

The RMS in Reachview is not an expression of the absolute accuracy, but the offset from the mean derived position (@egor.fedorov / @tatiana.andreeva, please correct me if I am wrong?).

As such it only describes the spread of the reported position. The Receiver has no way of knowing where the real Earth-bound position actually is.

In my opinion, the floating solution of the RS+ single frequency solution is only marginally better Single/SBAS corrected solutions.
Float solutions on the multifrequency RS2 is “closer to home”, but of course, still nowhere near the accuracy of a Fixed solution.

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Thank you Chistian, your answer look like interesting about the difference of technology between L1 floating and L1 + L2 floating solution. However, the indicator RMS that has show by app it is very unreliable.

Other thing, when you to try assign manually the geodesic coordinate at base, the negative sign not work, only can you use the copy and paste from some note app, it is a problem when you live at southamerica.

Thank you

What do you mean by unrealiable?

This is due to the native keyboard of tablets/phones operating system, not a setting in Reachview. Are you using Android?

Yes, I am using Android, what is your suggestion.


Oh yeah that is annoying, i am on android 8 something and i just keep thinking that this issue will someday just go away but it hasnt.

Phew! For once an assumption was spot on :smiley:


Thank you for your answer. The problem is that when you take, for example, the edges of a pool, the RMS say good solution and 3D position has less of 5 cm by point for a float solution, but the real difference are meters and the apexes of the figure not are showing of course, the pool . At general, the Fix solution is the 30% of the cases at the surveying work. I think that RMS in the app show differencial correction, but the real is the precision of a single position, look like complicate to take a decision sometimes, when you not get a fix solution.

You are mixing 2 different things. The RMS in Reachview doesn’t say anything about the absolute position. It says about the spread of the current solution. Lack of spread in the RMS isn’t equal to high confidence in absolute positioning confidence.

Another thing is that even when fixed, you still need to add the receiver-deviation + ppm per baseline to your STD. At a baseline of 10 km that usually equates to low 1-digit cm Standard Deviation.

With RS+, you should only rely on the Fixed solution. In the survey-tab, keep an eye on the PDOP. If above 1.8-2, you are heading for trouble, if below 1.4-1.5, you are good to go (in general, “your milage may vary”). These numbers are quite low, and demand quite good sky-view.

If you only get a fixed solution 30% of times, you need to rethink your choice of positioning method/technology.
The RS+ shines in areas where you don’t have obstacles within ~30 deg (from the horizon) dome above the receiver.
If you primarily are working suburban or areas with (mild) tree-cover, you should consider the multifrequency RS2.
If you have heavy tree-cover, or lots of very tall buildings, even a multifrequency GNSS solution might not be enough for cm-accuracy. That would be total station territory.


Thank you Christian, I will check it. Do you know when will be the new firmware for work with UTM?.

Dear Christian,

I have attached a imagen of solutions for the same position, there are fix and float. The difference between fixes records are more than one meter and in elevation much more. The float solution is Ok., however the RMS for all is very good, all less of 5 cm. Could you help me with this problem. Maybe will be the new firmware…

Can you post some Pictures of your environment for these points?
Your raw-logs would also be very helpful!

This records was taken over the same physical point. The difference between fixes records was more of the meter.

Then you have false fixes due to poor SNR.

Can you provide the raw logs, then it is much easier to see what is going on?

Let me 5 minutes, thank you

However, I need the Rinex or .ubx file from the Logging tab, if you have them?

Only those can tell us about the SNR and so on.

I don´t have RINEX, because is a data RTK. I will do other test and will log the data. Thank you.

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I have the firmware : 2.20.8