Adjust TCI RX gain per channel¶

The TCI Server applet provides a gain slider for each of its four RX channels. Adjusting these lets you match the audio level that TCI clients (such as Log4OM or SunSDR tools) receive from each slice.

Before you start¶

The radio must be connected. The TCI applet requires an active radio connection.
The TCI Server applet must be visible. If the applet panel is not showing, click the TCI tray button on the right sidebar to reveal it.

Steps¶

Click the TCI tray button on the right sidebar to open the TCI Server applet.
Locate the RX1, RX2, RX3, or RX4 row for the channel you want to adjust. The slice assignment label next to the channel name (for example, Slice A) shows which slice is driving that channel. A — means no slice is currently assigned.
Drag the meter/slider for that row left or right to set the gain. The value is saved immediately.
Repeat for any other RX channels you want to adjust.

Enable the TCI server¶

The Enable button starts or stops the TCI server.

In the TCI Server applet, locate the Enable button. It displays Disabled when the server is off and Enabled when the server is running.
Click Enable to start the server. The button text changes to Enabled.
To stop the server, click Enable again. The button text changes to Disabled.
If the server fails to bind to the specified port, the button text reverts to Disabled and the status indicator shows (port in use) in red.

The Enable button state is initialized from the AutoStartTCI setting. If AutoStartTCI is set to True, the button starts as Enabled and the server starts automatically when the applet loads.

Set the TCI port¶

The Port field sets the TCP port the TCI server listens on.

In the TCI Server applet, locate the Port text field.
Enter a port number between 1024 and 65535.
If you change the port while the server is running, the server restarts automatically on the new port.
Out-of-range values snap to 50001.

The Port field has an accessible name of "TCI port" with a description of "TCP port the TCI server listens on".

What each control does¶

Control	Default	Valid range
RX1 gain meter/slider	0.5	0.0 – 1.0
RX2 gain meter/slider	0.5	0.0 – 1.0
RX3 gain meter/slider	0.5	0.0 – 1.0
RX4 gain meter/slider	0.5	0.0 – 1.0
TX gain+meter	Drags set the TCI TX gain and emit tciTxGainChanged. Right-click opens TX overflow-mode picker (Clip / NaNGuard / Measure).	TciServer::setTxGain persists TciTxGain internally; UI mirrors the stored value. TCI TX audio is always allowed regardless of platform or hosted-DAX availability (evaluateDaxTxPolicy now unconditionally allows DaxTxRequestReason::TciTxAudio, v0.9.5.1, #2276). Right-click menu lets users choose how out-of-range (>1.0) samples from digital-mode clients are handled: Clip (saturating ±1.0, legacy default), NaNGuard (pass-through, only zero NaN/Inf), or Measure (true bypass with clip counting). Default is Clip so existing users see no behavior change (#3065).
Slice assignment label	—	— or `Slice <letter>`
TX overflow mode (right-click)	Clip	Clip, NaNGuard, Measure
Enable button	Disabled (or Enabled if `AutoStartTCI` = True)	Disabled or Enabled
Port field	50001	1024 – 65535
Server status indicator	(stopped)	(stopped), `:<port> (N clients)`, or (port in use)

Each meter/slider also displays a live RX or TX level using exponential smoothing — fast attack, slow decay — so the bar reflects signal activity on that channel while the drag position sets the gain.

The slice assignment labels now render slice letters with rich text formatting (#2606). This allows external slice indicators (for example, a colored or styled marker on the slice letter) to display correctly in the status label. The label text is generated using SliceLabel::richText() instead of a raw letter, ensuring any HTML formatting embedded in the slice's representation is preserved.

Each meter/slider has an accessible name set for screen reader compatibility. The RX gain sliders are named "TCI RX 1 gain" through "TCI RX 4 gain", and the TX gain slider is named "TCI TX gain". The Enable button has an accessible name of "TCI server enable" with a description of "Start or stop the TCI server".

Right-click the TX gain for overflow handling¶

The TX gain meter/slider has a right-click context menu that lets you choose how out-of-range (>1.0) audio samples from TCI clients are handled before they reach the radio.

Right-click anywhere on the TX gain+meter slider.
Select one of three overflow-handling modes:
Clip (saturating ±1.0) — Hard-clamp overshoots to ±1.0. This is the legacy default and introduces harmonic distortion on overshoots but protects downstream int16 conversion.
NaN guard (zero NaN/Inf only) — Pass samples through bit-exact; only zero pathological NaN/Inf values. Preserves digital-mode tone fidelity; out-of-range floats still reach the radio.
Measure only (true bypass) — Never mutate samples. Counts overshoots for telemetry; the downstream int16 conversion still clamps in the radio-native DAX route.

The selected mode is persisted as the TciTxOverflowMode setting (value 0, 1, or 2) and restored on next startup. Default is Clip so existing users see no behavior change (#3065).

What each TX overflow mode does¶

Mode	Value	Behavior
Clip	0	Saturates samples at ±1.0. Defensive default; introduces harmonics.
NaNGuard	1	Passes samples through unchanged except zeroing NaN/Inf. Bit-exact for digital tones.
Measure	2	True bypass — never mutates samples. Counts overshoots for telemetry.

Server status indicator¶

The server status indicator shows the current state of the TCI server:

(stopped) — The server is not running.
: (N clients) — The server is running on the specified port with N connected clients.
(port in use) — The selected port is already in use by another application. The status text appears in red.

Tips¶

The slice assignment labels (for example, Slice A) follow the DAX channel mapping. If a slice's DAX channel assignment changes, the label updates automatically.
Gain values are persisted as two-decimal floats (for example, 0.75). They are restored the next time AetherSDR starts.
The TX overflow mode is particularly useful for digital modes where out-of-range samples must be preserved without clipping for bit-exact tone fidelity. Use NaN guard for digital-mode operation and Measure for diagnostic telemetry.

Troubleshooting¶

A channel shows — and passes no audio to the TCI client — No slice is assigned to that DAX channel. Assign a slice to the corresponding DAX channel in your radio setup so TCI RX audio is routed to that channel.
TX overflow mode selection does not persist — Check that AetherSDR has write permission to its settings file. The TciTxOverflowMode setting is stored in the application settings.
Server status shows (port in use) — The selected port is occupied by another application. Choose a different port number in the Port field.
Enable button does not start the server — Verify that the port number is valid (1024-65535). If the port is in use, the button reverts to Disabled and the status shows (port in use).