S100 and German SAPOS

Dear all,

I have already had a thorough look at the troubleshooting section of the S100 manual, nevertheless, I am unable to obtain a FIXED RTK solution using the German SAPOS correction service.

The S100 is up-to-date; SAPOS data is cross-checked using a STONEX S10 and a TRIMBLE R8; VRS mount point (distance approx. 4,7km) is selected, etc. pp.

50cm accuracy is the most I can get with the S100; the other devices range from 8mm to 1.2cm DRMS HZ.

Any further suggestions on what to do? Cold start of the RTK engine: already done.

Regards and many thanks.


The same question was replied back in October 27, 2020. What happened in-between? Why now?


It simply doesn’t work reliably. Every now and then RTK FLOAT switches over to RTK FIXED, but almost instantly reverts back to RTK FLOAT.

Please make sure you are using SAPOS-HEPS service VRS_3_2G mountpoint, which should be the easiest way to use S100 in Germany.

With VRS service, the baseline distance should only be couple meters. Your seeing 4.7Km baseline distance imply not using the suggested SAPOS-HEPS service, which would need to choose proper mountpoint as section 7 of S100 User Guide describes. Choosing incorrect mountpoint unsupported format RTCM data stream will result in unstable RTK operation that you observed.

Attached you will find the SOURCETABLE I can select mount points from.

It might have something to do with the fact that SAPOS in the federal state I live in only corrects GPS + GLO.

VRS_3_2G_SL is the one to use.

VRS_3_3G_Test appears should work, but since it has the word “test” in the mountpoint, meaning test phase, wouldn’t be surprised if it doesn’t work.

I will give it another try. Photos and a video will be taken.

Hi GPS+GLONASS only mount points will not give you an RTK Fixed solution with the S100. You need a full GNSS subscription (Beidu, Galileo, etc included) with the frequencies that the S100 works with on a proper RTCM format, as described in the manual. Ein nur GPS + GLONASS-Abonnement funktioniert nicht mit dem S100. Ich hatte das gleiche Problem.

Oder Oder vielleicht braucht man - bei einem nur GPS+Glonass Abo - eine große Anzahl von Satelliten für eine RTK Fixed Lösung, weiß ich nicht genau (hängt auch von den passenden Frequenzen ab, glaube ich).

Although I do not dare challenge Jackson.Lee (he is the expert), I am not sure VRS_3_2G_SL will work either, or it will work with a large number of satellites under a good PDOP condition…

Hi George,

Many thanks for your input.

Fact is, that in the Saar region of Germany these are the only mount points I can get. As you may have seen, the implementation of Galileo is in a test phase. Sooner or later it should become available for everyday use.

This morning, before the rain came in, I mounted the S100 on a carbon rod, 2 meters high, made sure that it had unobstructed views of the sky and let SAPOS do it’s magic for 5 minutes.

RTK FLOAT and FIXED back and forth. :weary:

In a couple of days, as announced, I will give it another try; this time with a full documentation of all steps taken.



RTK correction service in most parts of the world is GPS/GLONASS dual frequency only. Didn’t hear customer have problem using them. Below is an example of a customer using Nearest Station type of RTK correction service, RTCM3_NEAR, which would be at much larger distance than the SAPOS VRS. Would be quite baffling if unable to work with VRS_3_2G_SL. Best to provide log files for analysis as mentioned in S100 User Guide Appendix A-3 if unable to get stable RTK Fix. In case the phone is running Android 11, the LeFebure NTRIP Client no longer able to store files correctly on latest Android 11, will need to wait for the Polaris Connect App update that’ll come out before end of June that supports problem report logging.

El mismo problema tenemos en Ecuador, bastante inestable hacer ntrip con la red nacional del pais IGM.
Ellos usan Trimble 58900 scs GPS+GLONASS en RTCM 3 y RTCM 3.2 supuestamente los mensajes son compatibles pero nada y no han aportado con mucha ayuda

Please check with Ecuador reseller below about your issue. They sold a lot of S100 RTK receivers in Ecuador. Didn’t hear mentioning any problem.


Pues aquĂ­ todos los usuarios de Polaris tenemos el mismo problema y estamos a la espera a ver si existe alguna actualizaciĂłn con correcciĂłn de esos problemas, la Ăşnica forma de trabajar adecuadamente es con polaris base, con otras bases no funciona bien es muy intermitente el fix

I don’t know what your intension is here.

We declined your request to be our Ecuador reseller. Pointed you to check with our Ecuador reseller, https://www.allien-gnss.com/, who (1) sold many S100 to Ecuador customers without hearing any issue, (2) is the expert that administers, installed REGME-IP CORS, and provide REGME-IP NTRIP service that you complain S100 having problem with.

Yet you don’t contact our reseller who is the expert with REGME-IP that you’re using, who could help resolve your mentioned issue most efficiently, but writes flammatory comments doubting if S100 rover could only work well with S100 base.

If there is really problem with S100 working with REGME-IP CORS, why do you even ask to be our reseller?

What is your true intension here?


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Ninguna intención los equipos me parecen excelente para el precio que tiene simplemente que no están funcionando adecuadamente es muy intermitente el fix en este caso particular, no es comentario inflamatorio es simplemente un usuario que desea encontrar una razón técnica de lo que sucede y también somo expertos en conexiones cors, hemos montado estaciones propias desde hace mucho y con varias marcas la finalidad es llegar a un óptimo rendimiento del equipo sin necesidad de tener que comunicarse con medio planeta

Pdta adjunto una captura de gente que comparte lo que digo y si quería la distribución de sus equipos es por que me gusta, pero eso no quiere decir que me conforme con las respuestas que tu me das especialmente. NUploading: Screenshot_20210709_194245_com.whatsapp.jpg…

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2021.07.08 version 1.19 S100 User Guide has updated Appendix A-3 on Problem Reporting using the new 2021.07.04 version 1.56 Polaris Connect App. Can follow the procedure to provide base and rover log files to find out cause of problem.

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