The garbage characters still show up if I use either of those channels. My workaround has been if I just dont touch ttyGSM3 and immediately open cgps (or anything attached to gpsd) and dont close it, I wont have any issues. Makes me think it has something to do with gpsd letting go of serial channels when it doesn’t need them.
I’ve unfortunately been having other issues as well, though. One of the modules, the gps doesn’t find any satellites, it can get the starting list from assisted gps, but the signal to noise ratio stays at 0 for all of them, it will occasionally jump up to 10 or so then go back down, even after leaving it for a long time. The other module will find and connect in around 20 seconds in the same exact location. Im guessing it might be some kind of issue with the antenna? I tried swapping the gps antenna between the two, and that didn’t change anything, so Im thinking maybe a bad connection between antenna and gps module? I dont know how to verify/fix that though.
The other issue I am having is that the gyro data coming out of both of them is pretty noisy. The one with the gps issues has it fluctuate around +/- 5 deg/s on each of the axes, and the other one fluctuates around +/- 19 deg/s on the z axis and +/- 5 on the other two axes. Not really sure what could be causing that since the accelerometer and magnetometer are both putting out good data. I don’t think its a scaling issue, since if I rotate it 90 degrees, the corresponding gyro angle matches fairly closely. I am using the code straight from the github for this too. I tried changing the dps to +/- 500 (and swapped the gain to 0.0175 to match), but it was still pretty noisy at around +/- 4 deg/s on all axes.
Any advice on either of those issues would be appreciated, Im not sure on how to diagnose the gps issue, and Im not sure if that level of noise out of the gyro is normal or not.