can not get FIX solution with NEO-M8T

[bszdev]

Dear all, I try to use a NEO-M8T module with an Ntrip base server but i can't get the FIX solution in the rtknavi. I get the SINGLE solution only.

I connect the device via USB port and I use a high performance active GPS antenna. I set the following things: u-center

• RXM-RAWX
• RXM-SFRBX
• USB protocol out: UBX+NMEA

rtknavi

• Rover: serial port, u-blox format without commands
• Base station: NTRIP client, RTCM3 format
• Position mode is static, L1

I don't know what is the best configuration settings.

In the error/warning list i receive continuously the "no base station observation data for rtk" and the "point pos error (chi-square error nv=9 vv=xx.x cs=xx.x)" messages.

What do i do wrong?

Thank you!

[SaBe]

Nice to hear that someone else is working on NEO-M8T as well as I haven't yet managed to get anything out of it. Neither on Linux desktop or using RTKGPS+ on my phone. Use u-blox format and no commands as well. The RTKGPS on Android gives me orange status bar and message "timeout" on the screen. Haven't yet got any furhter debugging this. Close but no sigar!

[DavidKelleySCSC]

Here are the actual lines of code (see rtkpos.c) /* check number of data of base station and age of differential */ if (nr==0) { errmsg(rtk,"no base station observation data for rtk\n"); outsolstat(rtk); return 1; } That seem to reinforce that you have not base station observations. But first... A perhaps silly question. Do you in fact get single mode fixes out of it? [See if you can see decoded measurement data changing in RTKNAVI]

I was under the impression that the M8T provided ONLY the new "RAWX" message and not the RAW message which is used in the older 6T units. And that is not yet decoded by RTKLIB. Hence, for anyone using RTKLIB for this you were out of luck until one of us put a RAWX parser into the RTKLIB code base.

[tomojitakasu]

The parser of RXM-RAWX is already implemented in 2.4.2 p10. See No. 119 of the support info:

http://www.rtklib.com/rtklib_support.htm

Anyway, The "no base station observation data for rtk" implies a problem of the RTCM3 stream. Please check it by RTKNAVI: RTK Monitor - (1) Rover". The "point pos error (chi-square error nv=9 vv=xx.x cs=xx.x)" indicates bad sky-view. At first, test it in open-sky environment.

Tomoji Takasu.

[SaBe]

I got single solution working now that I updated my RTKLIB source tree. Thanks for pointing this out.s

Unfortunately, the current release of RTKGPS+ for Android seems to be based on p9 version, so it takes a bit of hacking to get that right.

Br, Sampo

On Sat, Jan 16, 2016 at 3:53 AM, Tomoji Takasu notifications@github.com wrote:

The parser of RXM-RAWX is already implemented in 2.4.2 p10. See No. 119 of the support info:

http://www.rtklib.com/rtklib_support.htm

Anyway, The "no base station observation data for rtk" implies a problem of the RTCM3 stream. Please check it by RTKNAVI: RTK Monitor - (1) Rover". The "point pos error (chi-square error nv=9 vv=xx.x cs=xx.x)" indicates bad sky-view. At first, test it in open-sky environment.

Tomoji Takasu.

— Reply to this email directly or view it on GitHub https://github.com/tomojitakasu/RTKLIB/issues/121#issuecomment-172145502 .

[viconnex]

Hi there, bszdev, could you "fix" your problem? I'm actually facing the same difficulties with my M8P receiver, which doesn't seem to get RTCM3 stream. I only get a SINGLE solution. I'm confused because the rover does received them when using ucenter. What would be the settings to apply on RTKnavi? Thanks! Mansouris

[bszdev]

Hi Mansouris, i couldn't fix my FIX solution problem. I couldn't deal with it nowadays.

Bszdev

[denniswu-conetec]

@victorbrun @bszdev Here is a video about getting started with RTK on ublox NEO M8P. RTKLIB starts at 3:34. Hope it helps.

[bszdev]

@victorbrun @bszdev Here is a video about getting started with RTK on ublox NEO M8P. RTKLIB starts at 3:34. Hope it helps.

Excellent!

Thank you so much!