I can confirm that this is definitely coming as part of RM3, probably at the end of this year/early next.
In the example in this post, headings were calculated by taking the difference of the positions logged by two separate Emlid reach units - this is a method sometimes used in commercial a "gps compass" and gives very accurate results. It is a shame that Emlid haven't done more with the IMU in the Reach - it would have been nice to be able to run with one unit, and also to see if pitch/roll could have been useful. Of course, these things can be separately logged with extra sensors, which is something we might also take a look at.

That is great news! Please PM/Email me if there is an opportunity to provide testing of RM3 in advance of the release.

Also, Is there a feature list for RM3? I'm looking at a new sonar unit specifically for working with RM to produce side-scan mosaics and charts. I'd like to know if there are upcoming changes that may impact the choice of sonar brand or model.

I'm planning to use a windows laptop with RM for data acquisition in the field, so direct sensors into the laptop may also be an option vs a plotter. Any detail would be helpful. The laptop also has its own internal IMU which can be accessed through Windows - this may also be an option for RM3.

Thanks!

I thought I'd update this thread with some information I came across reading the Emlid Reach RTK GPS and it's internal IMU. It looks like the IMU data is now accessible within the Emild Reach RS2, Reach and RS+:

https://community.emlid.com/t/imu-data-from-reach-kit/1743/75

However, further software needs to be run on the reach (Rs2) to output this as a NMEA sentence or to log:

https://community.emlid.com/t/ihttps://github.com/87yj/EmlidIMUmu-data-from-reach-kit/1743/75

It would be great if Reefmaster would integrate with the Emild units, either real-time, or for post processing.