Cat-relay is a tool to turn your SDR into a band scope/panadapter for your radio. It does this by synchronizing the frequencies and modes between your SDR software and your radio transceiver.
Please go to Release Page to download latest version of Cat-Relay. Mac and Windows versions don't require any installation, you can unzip it and double click to run. Linux users can download the source code version. In some Linux systems, you might have to install libxcb-cursor0.
Cat-relay was written in Python3 (3.13+) and can run on Mac, Windows and Linux. Ready to use executable files are available for Mac and Windows platforms.
Currently, Cat-Relay supports two SDR software - SDR++ and SDRconnect (SDR Play), both are cross-platform.
Cat-Relay may also work with other SDR software if it provide a Hamlib/Rigctl compatible TCP server. Choose 'SDR++' in that case.
Cat-Relay supports following radio control software:
- RUMlogNG (Mac)
- Flrig (cross platform)
- DXLab Commander (Windows)
- N1MM+ (Windows)
- QLog (cross platform)
Cat-Relay may also work with other radio control software if they provide one of 3 interfaces:
- DXLab Commander compatible TCP interface.
- Flrig compatible XML/RPC server.
- Hamlib/rigctld compatible TCP interface. Choose QLog in that case.
At this moment, only SDR++, SDRconnect, RUMlogNG, DXLab Commander, Flrig, N1MM+ and QLog are tested. MacLoggerDX may also work, except changing modes on SDR is not supported by MacLoggerDX.
To change settings, click the "Settings" button on the main window.
Most settings are self-explanatory. Here are some useful tips:
Make sure "SDR Port" matches the port number in SDR++'s "Rigctl Server" panel. Port number for SDRconnect is fixed to 5454 and not configurable (limitation of SDRconnect)
Make sure "CAT Port" matches the port number in your radio control software.
If you use N1MM+, make sure "CAT Port" matches the "radio" port in N1MM+'s "Broadcast Data" configuration page. For example, if the "Radio" box has "127.0.0.1:12060", put "12060" in Cat-Relay's "CAT Port" box.
On N1MM+ side, make sure the ip address in the "Radio" box matches the computer that runs Cat-Relay. If Cat-Relay runs on the same computer as N1MM+, it should be 127.0.0.1.
If you run all the software on the same computer (most people do), keep "SDR running on" and "CAT running on" as "This computer". If you run some software on another computer, then make sure you choose "Another computer", and put in the correct IP address.
Number of seconds before retry a failed connection. The default (10 seconds) should work fine in most cases.
Number of seconds between Cat-Relay syncs your SDR and radio. The default (0.1 seconds) should work fine in most cases. Increase this number if you notice your computer is not very responsive. It is not recommended to set this to less than 0.05.
Cat-Relay writes rotating log files named cat-relay.log. Messages are logged to this file and, when standard output is
available (for example when you run from a terminal), to the console as well. If you want to report an issue, attaching
the current cat-relay.log helps with diagnosis. Location of the logs is displayed on the bottom of the Settings window.
For Mac and Windows users, please go to Release Page to download latest binary version of Cat-Relay. If you are using Linux or you prefer running source code, here are some steps you can follow.
The easiest way to run Cat-Relay is using uv. After installing uv, open a terminal, go to the folder that contains Cat-Relay and runn following command:
uv run src/app.py
To install dependencies (you only need to do this once), open a terminal, go to the folder that contains Cat-Relay and run following command:
pip3 install -r requirements.txt
Open a terminal, go to the folder that contains Cat-Relay, and run following command:
python3 src/app.py
Don't close the terminal window, you can minimize it if you'd like to.
See How to Contribute for guidelines, especially when adding or changing SDR/CAT clients.