gnss bundle - part one

src/field/external_gps/index.md

@@ -52,7 +52,7 @@ It is strongly recommended to use the direct connection in the <MobileAppNameSho
 3. Tap on the **Manage GPS receivers** option. Here, you can see the currently used receiver.
 
    Tap on the **Connect new receiver** button.
-   ![Select GPS receiver](./mobile-app-connect-gps-receiver.jpg "Select GPS receiver")
+   ![Select GPS receiver](./mobile-app-connect-gps-receiver.webp "Select GPS receiver")
 
 4. Choose your GPS receiver from the list of Bluetooth devices. 
 
@@ -67,8 +67,11 @@ It is strongly recommended to use the direct connection in the <MobileAppNameSho
    ![GPS info from external GPS in Mergin Maps mobile app](./mobile-app-external-gps-info.jpg "GPS info from external GPS in Mergin Maps mobile app") 
 
 ### How to connect external GPS receiver in Android via mock location
-:::warning
-Mock location should be only used if you are unable to connect the external GPS directly in the <MobileAppNameShort /> .
+
+:::warning Mock location and Internal (fused) GPS provider
+Mock location should be only used if you are unable to connect the external GPS directly in the <MobileAppNameShort />. 
+
+When setting up external GPS receiver on Android via mock location, we recommend using the *Internal (fused)* receiver option in [GPS Settings](../mobile-app-ui/#gps-settings) as this will show if mocked location is detected in the [GPS info](../mobile-app-ui/#current-position-and-gps-info) panel.
 :::
 
 External GPS can be connected and configured in Android to provide mock location using GPS apps (e.g. [Bluetooth GPS](https://play.google.com/store/apps/details?id=de.pilablu.gpsconnector) or apps from specific GPS manufacturers) as a source of GPS signal. the <MobileAppNameShort /> and other apps in your device will get the GPS position from the external GPS. 
@@ -93,6 +96,10 @@ External GPS can be connected to your iOS device via Bluetooth. Depending on the
 
 ![iOS GPS receiver](./external-gps-ios.jpg "iOS GPS receiver")
 
+::: tip Internal GPS provider
+When setting up external GPS receiver on iOS, we recommend using the *Internal* receiver option in [GPS Settings](../mobile-app-ui/#gps-settings) as this will show if mocked location is detected in the [GPS info](../mobile-app-ui/#current-position-and-gps-info) panel.
+:::
+
 ## External GPS troubleshooting
 If you encounter issues with external GPS in the <MobileAppNameShort /> , make sure that:
 - your Bluetooth is turned on

src/field/gps_accuracy/index.md

@@ -15,7 +15,7 @@ Current GPS accuracy is displayed above the bottom navigation panel in the <Mobi
 The colour of the **GPS** button denotes the accuracy threshold that can be set in the [GPS settings](../mobile-app-ui/#gps-settings) in the <MobileAppNameShort />. By default, it is set to 10 m. The indicator is green when the accuracy threshold is met, otherwise it turns yellow.
 
 Tapping the GPS button opens the [GPS info panel](../mobile-app-ui/#current-position-and-gps-info), which contains information about the horizontal and vertical accuracy, as well as number of satellites in use.
-![GPS accuracy and GPS info in Mergin Maps mobile app](../mobile-app-ui/mobile-app-gps-info.jpg "GPS accuracy and GPS info in Mergin Maps mobile app")
+![GPS accuracy and GPS info in Mergin Maps mobile app](../mobile-app-ui/mobile-app-gps-info.webp "GPS accuracy and GPS info in Mergin Maps mobile app")
 
 If you'd like to have higher accuracy, you can wait for your device to acquire a better GPS signal. For precise measurements, you may need to connect your device to an [external GPS](../external_gps/).
 

src/field/mobile-app-ui/index.md

@@ -99,18 +99,25 @@ Tapping the **location button** in the right bottom corner of the screen centres
 In the left bottom corner of the screen, there is a **GPS** button that displays the GPS accuracy as reported by your mobile device. The colour of the button denotes the accuracy threshold set in [GPS settings](#gps-settings) in the <MobileAppNameShort />.
 
 Tapping the GPS accuracy button opens the GPS info panel:
-![GPS info panel](./mobile-app-gps-info.jpg "GPS info panel") 
+![GPS info panel](./mobile-app-gps-info.webp "GPS info panel") 
 
-- **Source**: internal GPS of the mobile device or [external](../external_gps/) GPS receiver connected via Bluetooth
+- **Source**
+   - *Internal* for the GPS of the mobile device
+   - the name of the receiver for [external GPS](../external_gps/) receiver connected via Bluetooth
+   - *Mocked position provider* if the use of [mocked location](../external_gps/#how-to-connect-external-gps-receiver-in-android-via-mock-location) is detected
 - **Longitude, Latitude**: current position
-- **X, Y**: current position in project's coordinate reference system
+- **X, Y**: current position in the project's coordinate reference system
 - **Horizontal** and **Vertical accuracy** of the GPS position
-- **Altitude**: ellipsoidal height if internal GPS is used. [External GPS](../external_gps/) devices usually return orthometric heights (ellipsoid with the geoid separation applied).
+- **Altitude**: orthometric height
+   - for internal GPS, it is calculated from the ellipsoidal height using the <NoSpellcheck id="EGM96" /> geoid model by adding the geoid height (undulation) 
+   - for [external GPS](../external_gps/), it is the orthometric height as reported by the external GPS
 - **Satellites (in use/view)**: number of satellites
 - **Speed**
 - **Last fix**: time of the last received GPS position
 - **GPS antenna height** that can be set in [GPS settings](#gps-settings)
-
+- **Geoid separation**: geoid height (undulation)
+   - calculated from the <NoSpellcheck id="EGM96" /> geoid model for internal GPS receivers
+   - as reported by the [external GPS](../external_gps/)
 
 ### Sync
 The **Sync** button can be used to synchronise changes during the field survey. 
@@ -162,7 +169,7 @@ To open the **Settings**, tap the **More** button. In Settings, you can find [GP
 
 ### GPS settings
 - **GPS accuracy threshold**: value used to change the colour of GPS accuracy indicator to yellow
-- **Manage GPS receivers**: option to switch between internal GPS and external GPS receiver connected via Bluetooth. See [External GPS](../external_gps/) for more details.
+- **Manage GPS receivers**: option to switch between internal, internal (fused) and external GPS receiver connected via Bluetooth. See [External GPS](../external_gps/) for more details.
 - **GPS antenna height**: option to enter the height of a GPS antenna (e.g. when a surveying pole is used)
 
 ![Mergin Maps mobile app GPS Settings](./mobile-app-gps-settings.jpg "Mergin Maps mobile app GPS settings")

src/layer/variables/index.md

@@ -43,7 +43,9 @@ Following variables are supported:
  - `@position_coordinate` - A point with the coordinates in WGS84.
  - `@position_latitude` - Latitude
  - `@position_longitude` - Longitude
- - `@position_altitude` - Altitude
+ - `@position_altitude` - Orthometric or normal height
+ - `@position_altitude_ellipsoidal` - Ellipsoidal height
+ - `@position_geoid_separation` - Geoid or quasi-geoid height (undulation)
  - `@position_direction` - The bearing measured in degrees clockwise from true north to the direction of travel.
  - `@position_ground_speed` - The ground speed, in meters/sec.
  - `@position_vertical_speed` - The vertical speed, in meters/sec.