Post-processing RINEX 2.11 *.obs file with apps gdps

I’m trying to post-process readings acquired with one single REACH RTk (the older version).
I’ve tried to upload my *.obs file to
but it seems the system cannot process it:
“Sorry, APPS failed to process your request”
yet it is a supposedly compatible RINEX 2.11 file,
Any idea why could it be?
Any alternative?

My test file:


Hi @alobo,

Have you tried to convert obs file to Rinex 2.11? You can do in RTKConv software, just choose Rinex 2.11 in Options.

Is not my obs file a Rinex 2.11 file? This file was within
the file downloaded from REACH using ReachView:, along
with raw_201902161205.nav and raw_201902161205.gnav


I’ve tried to reproduce.

It seems the Single Frequency option isn’t available:

Which option did you choose?

You are right, no L1 option is available with apps gdgps…
Do you know of another solution?


If this service doesn’t accept L1-only, I’m afraid, there is no other solution.
Have you tried to reach out to their support to make sure it doesn’t work with Single frequency?

I mean if you can advise another service, I have confirmed that apps gdgps cannot process data
from L1-only devices


I hardly can advise any certain service. Hope somebody from our users will help you with this question.

By the way, it might be of interest to you to take a look at our GPS Post-Processing guide in RTKLib software.

Have you tried NRCAN?

PPP will only give you a rough estimate of the position with L1 and short observation time.
raw_201902161205.pdf (920.5 KB)

Many thanks for the useful advice. I thought apps gdps and/or the Canadian service you mentioned were using the closest publically-available GNSS station.
Is there a way to use the rinex files from an official base station located at 18km that I can download?
Would I need to use rtklib for this?
What accuracy would I have in that case, assuming ~20 min readings?
I have a second REACH RTK unit (the older model, not the M+), that I understand can be set as base. Would I then improve the accuracy? Would this be better than using the official GNSS station?
Please note I’m always referring to post-processing, not to real-time positioning. My purpose is getting ~6 GCPs with as much accuracy as possible.

Hi @alobo,

Sure, you can process Reach raw data with this RINEX file in RTKLib.

With such a baseline, you should gain centimeter-level accuracy.

I don’t think there will be a difference in accuracy. The baseline in 18 km is good for post-processing. So, if you’re going to use PPK, you don’t need to set up the local base in your case.

no these services just apply the more accurate ephemeris provided by IGS. as TB_RTK stated try the NRCAN service they will do just L1.

but from what i have tried and read i would not expect cm level accuracy, this may be helpfull…

Very helpful and instructive document.
Thank you all. I will take the rtklib path

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I am trying to post process with an old version of Topcon Tools. I managed import a Rinex 2.12 version file into Topcon and it loads ok and established vectors to the Base station. But it won’t post process. Do I have to enter antenna parameters into Topcon as there is no antenna type/specs for Reach RS. Any suggestion would be helpful. Torre

Hi @ecoscience,

Reach RS+ is an L1 receiver, it doesn’t require antenna calibration.
Have you tried to contact Topcon support? I think they can provide you with more efficient recommendations regarding this question.

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