[Help needed] GPredict, ICOM-910h and M2-RC2800Px problems

Hello All!
I work at the International Space University in Strasbourg, and amongst other things am responsible for our ground station here. One of the tasks I have been trying to implement recently is upgrading the software control of the GS to use GPredict for radio and rotator control.

Our set-up is:

  • Rotator controllers: M2-RC2800px (El90/Azi360, North Stop)
  • Radio: ICOM910h (set to splitmode)
  • GPredict + Hamlib (latest version for Ubuntu)
    (We have edited GPredict to not update the frequency from the dial, to stop the freq drift issue)
  • We are trying to receive in UHF and transmit in UHF (same freq before doppler correction).
  • We have the communications set up (I think ok) - it all checks out with Hamlib

I have been running into a number of problems though with this set-up
With GPredict/Hamlib and the ICOM910h

  1. The receive frequency will set and update with the doppler correction from gpredict
  2. The transmit frequency will not be set on the radio
  3. In hamlib, I have observed a error in setting F and I sequentially, eg I can set F (ok), set F (ok), set F (Ok), set I (get error), set I (Ok),… Although from what I understand this should not be a problem for U/U in split mode as we are not using the second band.

With GPredict/Hamlib and the M2-2800Px rotators:

  1. Generally the position can be set fine via hamlib or GPredict
  2. Every now and then (usually once or twice a pass) the Azi rotator gets sent to zero and back again. This seems to be not linked to a particular Azi… I have seem it at 135deg, 40 deg, etc… Our software and hard stops are 0/360 deg.

My default config is Sat32PC_ISS and Nova for Windows, which is clunky, but does not give any problems currently

Any help or insight would be greatly appreciated!


Hi @barnaby

Did you try selecting the different radio types in gpredict? By default the IC-910 is used as full duplex and it is indeed this operating mode that is believed to be broken. It may work in simplex mode though. Simplex here means “half duplex” - need to fix that also :grinning:

Can you confirm that you are using the latest code from the git repository?

I have access to a radio now, but I don’t know when I can find some time to analyse and this issue. Moreover, as you may have seen from other discussions, there is much needed work being done rewriting the radio and rotator controllers and it makes no sense to work on specific radio support before that work is done.

So, the best I can recommend for now is to stand by until we get closer to have something that can be tested.

Hi, I’m working on this project now at ISU as well, and was wondering if progess ever got made on the duplex issue @csete?