I wanted Gpredict to drive my IC-7100 automatically during satellite passes, handling both Doppler correction and mode switching without me riding the VFO by hand. Gpredict doesn’t talk to radios directly; it hands rig control off to Hamlib’s rigctld, which sits between Gpredict and the radio over CI-V. Here’s how I got the two talking on Linux.
Find the Hamlib model number Link to heading
Hamlib needs to know which model you’re using. List the supported rigs and grep for the IC-7100:
rigctl -l | grep -i 7100
Start rigctld Link to heading
The IC-7100 is Hamlib model 3070. With the radio connected via USB, start rigctld:
rigctld -m 3070 -r /dev/ttyUSB0 -s 9600 -t 4532
| Flag | Description |
|---|---|
-m 3070 |
IC-7100 Hamlib model |
-r /dev/ttyUSB0 |
serial device |
-s 9600 |
baud rate (match the CI-V baud rate set on the radio; try 19200 or 115200 if 9600 doesn’t work) |
-t 4532 |
TCP port Gpredict connects to (4532 is the default) |
rigctld will keep running in the foreground, listening for TCP connections and translating them into CI-V commands for the radio.
Configure Gpredict Link to heading
With rigctld running, point Gpredict at it:
- Open Edit > Preferences > Interfaces, then the Rigs tab
- Click Add new and set Host to
localhostand Port to4532
- Save the configuration, then open the radio control toolbar in the satellite tracking window and hit Engage to connect
Once engaged, Gpredict streams Doppler-corrected downlink and uplink frequencies to rigctld, which forwards them to the IC-7100 in real time as the satellite moves through its pass.
Fix permission errors on /dev/ttyUSB0 Link to heading
If rigctld can’t open the serial device, it’s almost always a permissions issue. Add your user to the dialout group:
sudo usermod -aG dialout $USER
Log out and back in for the group change to take effect.