Third party base(south gnss) corrections to simpleRTK2B V1

Q&A forumCategory: QuestionsThird party base(south gnss) corrections to simpleRTK2B V1
lall asked 7 months ago

Is possible to fed corrections from a third party(gnss)?
Configuration:
Base: south gnss g1
   output: serial RTCM3.2
Rover: simpleRTK2B V1
input: by the Differential GNSS interface in u-center:
UBX-RXM-RTCM:

In GNGGA: The field for “Age of DGNSS Corr” is empty.
I also tested:
base -> rover
ardusimple to ardusimple : no problems fix in < 45sec
south to south: no problems fix in < 30 sec
is there another way to debug other than rxm-rtcm?
Thanks

2 Answers
clive1 answered 7 months ago

I’d inspect the message content..
Guessing the MSM4 messages contain only L1 data, or have a different subset of satellites.
Not sure the GLONASS message will be accepted absent a 1230 bias message.
Perhaps you can look at what UBX-NAV-SIG reports in terms of RTCM/SBAS data for each SV and band, and if that is enough to do anything with at a carrier level.

lall answered 7 months ago

After a second test, I saw 1124(MSM4 Beidou) RTCM message being send by the south base when it got a single one Beidou in the sky view. a few seconds after that reach FIXED mode.
when, I disable the 1124 from the corrections(using SNIP) FIXED mode is lost(tested several times).
1124_fixed
snip decoder:
snip_decoder_RTCM
Also beidu satellites are not used on the carrier solution.

There is a way to avoid the need for a 1124 RTCM message in F9P configuration?, why does the f9p need it?

clive1 replied 7 months ago

1230 allows it to understand the base receiver’s handling of the Glonass frequencies (satellites each have a different carrier frequency)
Really don’t know if BEIDOU is helping, you could select GPS+GLONASS or GPS Only via the uBlox Series 9 Configuration.
If the receiver keeps reverting to Float is can be because the observations it gets from the Base are noisy, or counterproductive.