Can't parse MSM3 messages

[juffe84]

Hello.
I have one stream what I can't parse with rtklib.
Snip show like this.

RTKNAVI and strsvr cant parse it. What is problem?

MSM3.txt

Here is also RAW file from strsvr. Couple of seconds.

[ourairquality]

There is no MSM3 support, but these messages should be skipped properly. Can you use MSM4,5,6 or 7.

[juffe84]

No. I can't change message types. Too many user with MSM3 in this stream. 😁

Only what I need to do is convert this stream to legacy rtcm3.0 that I can use also Trimble R8.

[ourairquality]

The later trimble R8 models might support MSM7. Are you wanting to receive a MSM3 stream for a RTKLIB based rover, and where the available base streams are MSM3? MSM3 is limited, modulo 1ms ranges, needs clock steering, and clocks need to be close, and a lot of lower end receivers might not be suitable. If just wishing to pass through the MSM3 data then can it just be handled as raw data without parsing it.

[ourairquality]

Btw RTKLIB does have MSM1,2,3 encoding support, but still not sure how well that would work with the low end receivers that jump the clock.

[juffe84]

I'm sure that my R8 (model2?) only support legacy RTCM 3.0 and Its only GPS, Glo receiver. But pretty good 😁.

[juffe84]

I want to use my R8 on the place where is only MSM3 signal. MSM3 signal is coming from high end receiver. But what we need that we can get decode_msm3 function? Is it complicated to code? So I want to decode and then encode MSM3 to legacy RTCM3.0 with strsvr

[ourairquality]

The complexity is filling in the missing rough range, as MSM1,2,3 have only the modulo 1ms range and don't encode enough data to decode a complete range, so it would need to compute the satellite ranges from the base position and satellite ephemeris.