RTCM3 MSM QZSS signal 3 mapping

[ourairquality]

Notice at least some of the Trimble stations in the network are putting out a RTCM3 MSM QZSS signal id 3 which has no mapping in Ginan, e.g. PKVL00AUS0. This is seen on J04 and J08 and at a guess this is L1C/B (rinex 1E). See https://qzss.go.jp/en/overview/services/sv03_signals.html

Could you look into the origin of this mapping and if appropriate could Ginan including the mapping for this signal. An entry in rtcmDecoder.cpp sysIdSignalMapMap adding {3, {3, F1, E_ObsCode::L1E}} if that is the correct mapping.

[ourairquality]

Also noted the Septentrio PolaRx5 5.7.0 release notes: "It is now possible to enable observables from the QZSS L1C/B signal in RTCM MSM output messages." There are a lot of these on the network too, some already running 5.7.0 but have not spotted one with a likely L1C/B signal, so still in the dark as to the MSM signal id allocation used and hopefully it is the same as Trimble are using.

[ourairquality]

The VIC GPSnet have also enabled the QZSS L1C/B signal on the PolaRx5 receivers and I can confirm that the RTMC3 MSM stream signal index is the same as for the Trimble Alloy receiver streams, see for example MVIL00AUS0.

[seballgeyer]

We agree the observed mapping is likely correct in practice, but Ginan should follow the RTCM signal table rather than receiver-specific behaviour. We will implement this once RTCM publishes the relevant amendment.

[ourairquality]

Fwiw BNC accepted this and commented on the provenance see https://software.rtcm-ntrip.org/ticket/221 and it might be coming out of the RTCM standard process.

Would add that the L1C/B signal appears to use the same hardware path as Galileo so it might be a small step to see it available on low end gnss receivers, L1-L5 receivers. Noted that uBlox has also added support for this signal for their X20, it's in the raw data format, but have not checked their RTCM3 stream. Whereas don't see the L1L signal widely supported, might need a new hardware path, so L1C/B - L5 QZSS might be around for a while.