Subscribe to MQTT topics and toggle panadapter display¶
Add MQTT topic subscriptions and control whether each topic's latest value is shown as an overlay on the panadapter. This lets you monitor station telemetry — such as antenna rotator position, weather data, or amplifier status — directly on the spectrum display.
Before you start¶
- You must have a working MQTT broker accessible from your AetherSDR machine.
- The MQTT applet must be visible (toggle the MQTT tray button on the right sidebar if it is hidden).
Steps¶
- Open the MQTT Settings dialog: go to Settings > MQTT... or click Settings... in the MQTT applet header.
- Click the Subscriptions tab.
- Click Add to insert a new row in the topic table.
- Double-click the Topic cell and type the full MQTT topic string (e.g.
rotator/azimuth). - Under the Display column, check the box to show the topic's latest value as an overlay on the panadapter. Leave it unchecked to subscribe without displaying.
- Click Apply to save the subscription list without closing the dialog, or Ok to save and close.
- In the MQTT applet, click Off to toggle to On and connect to the broker.
What each control does¶
| Control | Purpose | Default |
|---|---|---|
| Topic table | List of subscribed MQTT topics. Each row is one topic. | (empty) |
| Display checkbox | When checked, the topic's latest received value appears as an overlay on the panadapter. | Unchecked |
| Add | Inserts a new blank row in the topic table. | — |
| Remove | Deletes the selected row(s) from the topic table. | — |
| Internal AetherSDR Topics | Read-only list of topics subscribed automatically (e.g. antenna alias updates). These cannot be removed. | See the read-only list in the dialog |
| Settings... | Opens the MQTT Settings dialog (MqttSettingsDialog) for broker connection, subscriptions, and publish button configuration. | New in v26.5.3. Replaces the inline Host/Port/User/Pass/TLS/Topics fields. |
| Publish buttons | Click publishes the configured payload to the configured topic via MqttClient::publish. Buttons are configured in the MQTT Settings dialog. | Only active while connected. Configured via MqttSettingsDialog Publish Buttons tab. |
| Message log | Displays received messages as 'topic: value' lines, and transmitted messages as 'TX topic: payload' lines. Also processes antenna alias updates from MQTT. | Capped to 50 entries. |
| Enable (Off/On) | Connects or disconnects from the broker using settings from MqttSettings. Emits connectRequested / disconnectRequested and saves connection enabled state. | Password is loaded from system keychain on first enable. If keychain password is not yet loaded, shows 'Waiting for keychain' status. |
| Status label | Shows connection state: green "Connected", grey "Disconnected", or default color error message. | "Disconnected" |
Tips¶
- The panadapter overlay shows the value of the most recently received message for each topic with Display enabled. Overlay labels are truncated to fit, so keep topic names short.
- A topic is subscribed immediately when you connect to the broker (toggle On in the applet). You do not need to reconnect after changing subscriptions — toggle Off then On to apply changes.
- If the status label shows "Waiting for keychain", the system keychain password has not yet been loaded. Toggle Off then On again to trigger keychain retrieval.
- The message log now also shows transmitted messages with a "TX" prefix, helping you confirm that publish buttons are working.