§ 005. Convert RTCM3 corrections to RINEX

Intro

Let's consider practical use-case when we have RTCM3 corrections in hands but RINEX observables are needed. Typically it is need for rover and base data post-processing (PPK). For instance, TOPAZ PPK operates w/ RINEX files only.

Concrete file w/ binary RTCM3 corrections used in the article is streamed from http://euref-ip.net NTRIP Caster, mountpoint BELL00ESP0.

Example of how to convert RTCM3 corrections to RINEX

RINEX Tools online service will be used. Besides merging / editing RINEX and converting UBLOX UBX, it also able to convert RTCM3 (including MSM messages) to RINEX observables. Choose Convert RTCM3 to RINEX option at first step.

Next choose RTCM3 file. Also, please specify GPS date when corrections are started to be logged. Information about date is vital since RINEX epoch must be tagged to full date and time while RTCM3 epoch operates w/ time withing week w/o date.

In fact, there are some RTCM3 messages which may help to get idea of date. These messages are: 1013 (System Parameters) and/or ephemeris (1019, 1020, 1042, 1044-1046). However, usually these messages are missed in the stream.

At next step, you could specify output RINEX version (RINEX2, RINEX3 and RINEX4 are supported). Also decimation and GNSS filter may be used. Once converting is completed, RINEX observation file is downloaded automatically in ZIP form.

Summary

Many of PPK and PPP post-processing software operate w/ RINEX only (or do internal converting to RINEX). That is why sometimes it is needed to convert RTCM3 log to RINEX. The article provides example of how to convert RTCM3 binary corrections (including MSM messages) into RINEX observables w/ help of RINEX Tools service.