Fix TCI TX Silent on Windows or Linux without PipeWire¶
TCI TX audio is routed through a dedicated dax_tx stream slot inside AetherSDR's TCI server, independent of the Windows SmartSDR DAX2 audio device path and independent of PipeWire. This means TCI TX should work on all platforms without any special configuration. This page helps you confirm the TCI server is set up correctly and the TX gain is not the cause of silence.
AetherSDR must be connected to the radio. The TCI applet requires an active radio connection.
The third-party application sending TCI TX audio (for example, a digital-mode program) must be configured to connect to AetherSDR's TCI server, not to SmartSDR DAX2 or any other audio device.
Make sure you are running AetherSDR v0.9.5.1 or later. Earlier versions had a platform-dependent TX audio policy that could block TX audio on Windows and Linux without PipeWire.
Click the TCI tray button on the right sidebar to open the TCI Server applet.
Check the server status label next to the Port field.
If it reads (stopped), click Enable to start the server.
If it reads (port in use), the chosen port is already bound by another process. Change the value in the Port field to a free port (valid range: 1024–65535; default: 50001), then press Enter and click Enable.
Confirm the status label shows :<port> (N clients) with at least one client connected. If your TX application is not shown as a connected client, check its TCI host and port settings and ensure they match the Port field value.
Look at the TX row in the applet. Check the slice-assignment label next to the TX meter.
If it shows —, no slice is currently designated as the TX slice. Use the radio's slice controls to assign a TX slice.
If it shows Slice <letter> (with the slice letter rendered in rich text, e.g., colored or styled), the TX path is active.
Drag the TX gain+meter slider to confirm it is not set to 0.0. The default is 0.5 (valid range: 0.0–1.0, persisted as TciTxGain). A value of 0.0 produces silence regardless of platform.
Key the transmitter from your third-party application and watch the TX gain+meter for level movement. If the meter shows activity, audio is reaching the server and the radio should be transmitting.
If you are using a digital mode that requires bit-exact tone fidelity, right-click the TX gain+meter slider to open the TX overflow handling menu. Select the desired mode to control how out-of-range (>1.0) samples from TCI clients are processed.
Right-click the TX gain+meter slider to open the TX overflow handling context menu. This controls how out-of-range (>1.0) samples from TCI digital-mode clients are processed before reaching the radio. The default is Clip to maintain backward compatibility.
Mode
Value
Description
Clip (saturating ±1.0)
0
Hard-clamp overshoots to ±1.0. Defensive default; introduces harmonics on overshoot but protects downstream int16 conversion.
NaN guard (zero NaN/Inf only)
1
Pass samples through bit-exact; only zero pathological NaN/Inf values. Preserves digital-mode tone fidelity; out-of-range floats reach the radio.
Measure only (true bypass)
2
Never mutate samples. Count overshoots for telemetry; the downstream int16 conversion still clamps in the radio-native DAX route.
Out-of-range port values snap back to 50001 automatically.
If you want the TCI server to start every time AetherSDR launches, enable Settings > Autostart TCI with AetherSDR. This sets the AutoStartTCI flag and also checks Enable on startup.
The TX meter uses fast attack and slow decay smoothing, so a brief transmission will keep the meter visibly elevated for a moment after audio stops. No movement at all during a keyed transmission confirms audio is not arriving from the client.
Slice assignment labels now support rich text rendering, so slice letters may appear with additional formatting (e.g., color) to indicate slice properties.
For digital modes requiring bit-exact tone fidelity, use NaN guard or Measure only modes to avoid harmonic distortion from clipping.
The applet container uses the theme system (applet/tci) for consistent styling across all themes.
The TCI server is explicitly torn down when AetherSDR closes to prevent a use-after-free condition, fixed in v0.9.7.
Status shows (port in use) and Enable snaps back to off — Another application is bound to that port. Enter a different port number in the Port field, press Enter, and click Enable again.
Status shows the correct port and client count, but the radio is not transmitting audio — Confirm the TX slice label in the TX row shows Slice <letter> and not —. If it shows —, designate a TX slice from the main UI. Also confirm the TX gain+meter is above 0.0.
Third-party application cannot connect — Verify the application is pointed at localhost (or AetherSDR's host IP) and the port number matches the Port field. Confirm no firewall rule is blocking the port.
TX meter shows no movement despite the client being connected and keyed — The client application may be sending audio to a system audio device rather than over the TCI WebSocket. Check the client's audio output or TCI audio routing settings. AetherSDR does not use the Windows DAX2 audio device for TCI TX; audio must arrive over the WebSocket connection.