Connect your radio to Open Signal
Point Open Signal at your rig's USB audio codec, choose a PTT method (VOX, serial RTS/DTR or CAT), and optionally add CAT frequency readout.
Open Signal talks to your radio the way every soundcard digital mode does: audio in, audio out, and (optionally) a serial line for keying and frequency control. All of it lives in Settings (the gear icon at the bottom of the left rail).
1. Audio — the essential part
Pick your radio’s USB audio codec as both the capture (radio → computer) and playback (computer → radio) device. For a rig with a built-in USB soundcard (FT-991A, IC-7300 and friends), it appears as something like “USB Audio CODEC”.
The RX LEVEL tile on the Receive screen should twitch when the band is open — that’s your proof the capture side works.
2. PTT — how transmit gets keyed
Choose one in Settings:
- VOX — the rig keys itself when audio arrives. Zero wiring, works everywhere; just set the rig’s VOX to respond to the data/USB input.
- Serial RTS / DTR — classic keying via a serial line.
- CAT command — keying over the rig-control protocol (Kenwood-style CAT or Icom CI-V), using the serial port and baud rate you set.
3. CAT frequency (optional but nice)
With a rig driver selected, the FREQUENCY tile shows the rig’s real dial and follows when you spin the VFO. Without CAT, the app uses the frequency you set in Settings — everything still works.
Rig-specific notes
- Yaesu FT-991A: use the rear USB; set the mode to DATA-FM for 2 m work and menu 071 (DATA MOD SOURCE) to USB — otherwise the rig keys but sends no audio.
- Keep the Windows sound “enhancements” off for the radio codec, and don’t let Windows use it as the default speaker.
If a direction fails to open, the status chips at the bottom of the rail go red — see Troubleshooting audio.
New to Open Signal?
Start with the overview — what it does, the honest status, and how the pieces fit together.