SatelliteInfo (QML) | Qt Positioning 6.5.1
Description: The SatelliteInfo example shows the available satellites using Sky View or RSSI View and the user's current position. The satellites currently contributing to the GPS fix are marked as pink.

- Qt 6.5
- Qt Positioning
- SatelliteInfo (QML)
- Qt 6.5.1 Reference Documentation

# SatelliteInfo (QML)

The SatelliteInfo example shows the available satellites using Sky View or RSSI View and the user's current position. The satellites currently contributing to the GPS fix are marked as pink.

This example demonstrates the usage of Qt Positioning QML API:

- PositionSource
- SatelliteSource

The example shows satellite information in two different tabs. The data is taken from the SatelliteSource::satellitesInView and SatelliteSource::satellitesInUse properties.

The Sky View tab shows the relative satellite positions using the `Azimuth` and `Elevation` attributes.

The RSSI View tab shows the signal strength of satellites in view using the signalStrength property.

In both cases, the displayed numbers are the individual satellite identifiers. The satellites that are currently used to calculate the GPS fix are marked pink.

The Current Position block below the satellite information uses PositionSource::position property to show the current latitude and longitude.

The Status block shows the current mode or the last error.

The application operates in three different modes:

Application mode | Description
--- | ---
Running | The application continuously queries the system for satellite and position updates. When new data is available it will be displayed.
Stopped | The application stops updating the satellite and position information.
Single | The application makes a single satellite and position update request.

The application automatically switches into a simulation mode if the platform does not provide satellite or position information. The simulation mode uses an NMEA plugin with pre-recorded NMEA data.

#### Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

#### Retrieving Current Position

The current position is retrieved from the PositionSource QML object. The `onPositionChanged` handler is used to receive position updates. The string representations of latitude and longitude are extracted from the coordinate property.

     PositionSource {
         id: positionSource
         name: root.simulation ? "nmea" : ""
         onPositionChanged: {
             let posData = position.coordinate.toString().split(", ")
             positionAndStatus.latitudeString = posData[0]
             positionAndStatus.longitudeString = posData[1]
         }
     }

#### Retrieving Satellite Information

Similarly to the position, the current satellite information is retrieved from the SatelliteSource QML object. The `onSatellitesInViewChanged` and `onSatellitesInUseChanged` handlers are used to get the updated satellites in view and satellites in use respectively. The data is then combined into a single model, which is passed to both Sky View and RSSI View tabs.

     SatelliteSource {
         id: satelliteSource
         name: root.simulation ? "nmea" : ""
         onSatellitesInViewChanged: root.updateModel()
         onSatellitesInUseChanged: {
             root.inUseIds.clear()
             for (var i = 0; i < satellitesInUse.length; ++i)
                 root.inUseIds.add(satellitesInUse[i].satelliteIdentifier)

             root.updateModel()
         }
     }

#### QML Module Registration

##### CMake Build

For a CMake-based build, we need to add the following to the `CMakeLists.txt`:

     qt_add_qml_module(satelliteinfo
         URI SatelliteInformation
         VERSION 1.0
         QML_FILES
             Button.qml
             Main.qml
             RssiView.qml
             PositionAndStatus.qml
             SkyView.qml
             ViewSwitch.qml
     )

##### qmake Build

For a qmake build, we need to modify the `satelliteinfo.pro` file in the following way:

     qml_resources.files = \
         qmldir \
         Button.qml \
         Main.qml \
         RssiView.qml \
         PositionAndStatus.qml \
         SkyView.qml \
         ViewSwitch.qml

     qml_resources.prefix = /qt/qml/SatelliteInformation

     RESOURCES += qml_resources

Example project @ code.qt.io