Allow signed RSSI values for telemetry links as input power will almost certainly be below 0 dBm

src/comm/MAVLinkProtocol.h

@@ -275,7 +275,7 @@ signals:
      * @param noise background noise level
      * @param remnoise remote background noise level
      */
-    void radioStatusChanged(LinkInterface* link, unsigned rxerrors, unsigned fixed, unsigned rssi, unsigned remrssi,
+    void radioStatusChanged(LinkInterface* link, unsigned rxerrors, unsigned fixed, int rssi, int remrssi,
     unsigned txbuf, unsigned noise, unsigned remnoise);
     
     /// @brief Emitted when a temporary log file is ready for saving

src/ui/toolbar/MainToolBarController.cc

@@ -52,8 +52,8 @@ MainToolBarController::MainToolBarController(QObject* parent)
 
     // RSSI (didn't like standard connection)
     connect(qgcApp()->toolbox()->mavlinkProtocol(),
-        SIGNAL(radioStatusChanged(LinkInterface*, unsigned, unsigned, unsigned, unsigned, unsigned, unsigned, unsigned)), this,
-        SLOT(_telemetryChanged(LinkInterface*, unsigned, unsigned, unsigned, unsigned, unsigned, unsigned, unsigned)));
+        SIGNAL(radioStatusChanged(LinkInterface*, unsigned, unsigned, int, int, unsigned, unsigned, unsigned)), this,
+        SLOT(_telemetryChanged(LinkInterface*, unsigned, unsigned, int, int, unsigned, unsigned, unsigned)));
 
     connect(qgcApp()->toolbox()->multiVehicleManager(), &MultiVehicleManager::activeVehicleChanged, this, &MainToolBarController::_activeVehicleChanged);
 }
@@ -96,7 +96,7 @@ void MainToolBarController::_activeVehicleChanged(Vehicle* vehicle)
     }
 }
 
-void MainToolBarController::_telemetryChanged(LinkInterface*, unsigned, unsigned, unsigned rssi, unsigned remrssi, unsigned, unsigned, unsigned)
+void MainToolBarController::_telemetryChanged(LinkInterface*, unsigned, unsigned, int rssi, int remrssi, unsigned, unsigned, unsigned)
 {
     if((unsigned)_telemetryLRSSI != rssi) {
         // According to the Silabs data sheet, the RSSI value is 0.5db per bit

src/ui/toolbar/MainToolBarController.h

@@ -80,7 +80,7 @@ signals:
 private slots:
     void _activeVehicleChanged          (Vehicle* vehicle);
     void _setProgressBarValue           (float value);
-    void _telemetryChanged              (LinkInterface* link, unsigned rxerrors, unsigned fixed, unsigned rssi, unsigned remrssi, unsigned txbuf, unsigned noise, unsigned remnoise);
+    void _telemetryChanged              (LinkInterface* link, unsigned rxerrors, unsigned fixed, int rssi, int remrssi, unsigned txbuf, unsigned noise, unsigned remnoise);
     void _delayedShowToolBarMessage     (void);
 
 private: