Reach RINEX conversion feature request

matt1973 · April 11, 2016, 12:17pm

I have been working on post-processing Reach output, with some good results, and have been in communication with the author of this excellent blog on using RTKLib. Having sent him some of my Reach data to play with, he commented on the fact the default RINEX conversion performed by the Reach module is not including the .nav files for any system other than GPS (e.g. gnav for Glonass). Without them, the extra satellites data recorded when e.g. logging GPS + Glonass are not used by RTKLib. Of course, you can convert the .ubx files yourself again to get these files but it would be very useful if the default Reach conversion would generate nav files for each system that was logged.

There is some other useful stuff that could be included in the conversion that isn’t - I’ll quote from my correspondence with the blog author here - could this also be made default?

Your observation files are missing doppler and SNR data. They will be included if you use the -od and -os options with CONVBIN. Doppler is used by RTKLIB if it is available to estimate receiver clock bias and velocity so it’s always best to have it if you can. SNR is not used with the default settings, but can be used by RTKLIB for filtering out lower quality data and provides insight when looking at the results, so I suggest you turn it on as well.

You did not include the .gnav files files in your RINEX folders. They are the equivalent of the .nav files for the GLONASS satellites so you will need them if you want to process the GLONASS satellites. That might explain why you did not see any improvement with the GPS/GLONASS data. It’s also possible you didn’t have the config file set properly to use them. You need to set “pos1-navsys” to “5” to enable use of GLONASS and “pos2-gloarmode” to “off” to disable ambiguity resolution for GLONASS.

thanks!

igor.vereninov · April 11, 2016, 1:00pm

Have you tried different Rinex version? In version 3 all systems data should be in .nav .

matt1973 · April 11, 2016, 1:13pm

No I will give it a go on my next logs…
Are you also exporting the doppler information in RINEX v3?

igor.vereninov · April 11, 2016, 1:14pm

It should be there, there is the rtkconv (CLI version of convbin) doing the conversion on Reach. If you spot the difference between doing something in convbin vs on Reach, with the same Rinex version please let us know.

matt1973 · April 11, 2016, 1:17pm

OK thanks Igor - my bad ! I believe that you do need to specify an extra command line option when using convbin, to get the doppler - I will check it when I next make a log.

igor.vereninov · April 11, 2016, 2:18pm

By the way, we have already included some fixes from rtklibexplorer into latest Reach update

matt1973 · April 12, 2016, 10:00pm

FYI Igor my logs were produced with RINEX 3.01. Have now changed that to 3.02 and will be logging some more data tomorrow, so I will see what happens during the conversion.

matt1973 · April 13, 2016, 2:30pm

Hi Igor,
What I can confirm is that - even if RINEX v3 contains all nav data in a single .nav file - RTKLIB does not use anything other than GPS satellites when post-processing Reach-converted data. If I convert manually and get separate nav/gnav files, then RTKLIB does use Glonass, and my solution improves. I’m not sure whether this is a conversion issue or an RTKLIB issue. If I get time, I may look into it further but for now my advice is to convert manually (using convbin 2.4.3). This is producing better results for me.

egor.fedorov · April 21, 2016, 4:31pm

Fixed in v0.3.2

matt1973 · April 21, 2016, 5:40pm

Thanks Igor. Do you know what the issue was? Is it now producing multiple .nav files or is all the nav data contained within one?

egor.fedorov · April 21, 2016, 5:49pm

It depends on the RINEX version you have selected. RINEX 3 contains all the data in the .nav file. RINEX 2 has separate files for different GNSS

matt1973 · April 21, 2016, 5:56pm

So are you confirming that there was an issue with the v3 export from Reach? Also - do you include the doppler information now? (-od option).

matt1973 · April 21, 2016, 5:57pm

So are you confirming that there was an issue with the v3 export from Reach? Also - do you include the doppler information now? (-od option).

egor.fedorov · April 21, 2016, 10:46pm

Yeah, it’s also in the newly converted logs