RTCM/VOTER Updated Firmware

I am not going to get in to the politics of the Github repo. I forked the RTCM/VOTER firmware part, prior to things going sideways, so I could do some development.

You can find my current work at: https://github.com/ve7fet/voter

If you look through the Releases, you will see I have made a bunch of changes to the code. Up to you, if you want to experiment. I have run them all on through-hole (VOTER) board, as well as on RTCM’s.

Lots of comments have been added to the code, after going over it for hours, and staring at the datasheets to figure out what is going on (I know specifically why Jim used 9.6MHz now, even though he mentioned it in the past to me).

Everything newer than v1.61 contains the mktime fixes that David Maciorowski, WA1JHK did to work around the mktime bug.

Since then, I’ve tweaked some of the GPS diags, added some support for fudging time by arbitrary amounts (if desired).

The latest (3.00) adds the ability to remotely adjust the squelch. You can select to use the hardware pot, or adjust it in software (nice if your RTCM is on a mountain top in winter). It also exposes the “hysteresis” tunable that existed in the source, but required re-compiling to change. Note that if you use this version, after you load it, you will need to set the Hysteresis manually to 24 (default)… minor bug I have to fix.

We’re pretty much out of space in the PIC now (had to delete the diagnostic cable display to make this latest version go).

That said, still on the road map is further investigation of how the squelch code operates, to see if there is some work there to make the squelch action better. I’ve graphed the functions it uses to calculate the squelch action, and I’m not thrilled with how it looks.

I also believe it is possible to change the code to use 9.8304MHz as the reference, instead of the current 9.6MHz crystal. 9.8304MHz is also known as “CDMA 8x Chip”, and is conveniently available on many surplus Nortel CDMA GPSTM modules… which also have a 10MHz GPSDO. This could make messing with simulcast a lot easier, as it is already well known that the 9.6MHz crystal won’t cut it for simulcast ops. I’ll need to do some hardware and software testing with this to see if it works (also need to see if the bootloader needs 9.6MHz to boot… that could be an issue).

Anyways, if you want to mess around, the firmware binaries are attached to each Release, which also explains the changes.

Cheers!

Lee

1 Like

Excelent! Thanks for your work on the RTCM code. I’ll give 3.0 a try soon.