Position variables not available/populated (@position_vertical_speed, @position_magnetic_variation); on iOS satellites info missing and “-1” values

[RastoHu]

Description

• In feature forms, the position variables @position_vertical_speed and @position_magnetic_variation are not available/populated for both internal and external GPS on Android and iOS.
• On iOS, the GPS info dialog does not show “Visible satellites” and “Used satellites” for Internal and External (Mock). In feature forms, satellite variables return -1 (e.g., @position_visible_satellites, @position_used_satellites).
• iOS: if External (Mock) provider is set, Horizontal accuracy and Vertical accuracy shows constant values:
  -> Horizontal accuracy: 5.00 m (constant)
  -> Vertical accuracy: 9.50 m (constant)
• Reproduced with internal GPS and with an external (mock) GNSS receiver.
• Network position provider - Satellites in use and in view are the same, e.g. 7/7
• Projects used: tester-ws-1/test_orthometric_heights or test_external_receiver

Related (for context): #1743 (vertical speed), #1753 (external GNSS satellite info). Those do not cover magnetic variation nor the iOS -1 counts with internal GNSS.

Environment
PROD

Application (+ app version, build, operating system)

• Actual Android app version: 2025.6.0
• Samsung Galaxy A53 5G, Android 15
• Actual iOS app version: 2025.5.0
• iOS 18.5, iPhone

Steps to reproduce

1. Open project tester-ws-1/test_external_receiver.
2. Ensure GPS has a fix.
3. Internal GPS: add new feature in GPS_data layer; in the form, observe fields:
   • @position_vertical_speed
   • @position_magnetic_variation
   • @position_visible_satellites
   • @position_used_satellites
4. External GPS: connect an external GNSS receiver, set it as the position provider, and repeat step 3.
5. On iOS, open the GPS info dialog and verify “Visible satellites”, “Used satellites”, “Horizontal accuracy” and “Vertical accuracy”.
6. Repeat for network position provider.

Actual results

• @position_vertical_speed and @position_magnetic_variation are not available/populated in the form (internal and external GPS; Android and iOS).
• iOS GPS info dialog: “Satellites (in use/view)” display N/A

• iOS GPS info dialog: “Horizontal accuracy” and “Vertical accuracy” display constant values (5.00 m/ 9.50 m).
• iOS feature form: @position_visible_satellites and @position_used_satellites evaluate to -1.
• iOS/Android: If the network position provider is configured, the number of used satellites is the same as satellites in view.

Expected results

• @position_vertical_speed and @position_magnetic_variation are available and populated when measurable (null only when not available).
• iOS GPS info dialog shows “Visible satellites” and “Used satellites”.
• iOS GPS info dialog shows “Horizontal accuracy” and “Vertical accuracy” or N/A ❓
• Satellite variables return 0 or positive counts (not -1) when a fix is available.

Screenshots or logs

Conclusion
Created by GitHub Copilot and supervised by a human test analyst.

[Withalion]

Some more info from testing: #4360

[Withalion]

1. @position_vertical_speed and @position_magnetic_variation - the values are missing because pretty much no provider supplies this information, maybe we should discuss if we even want to make it available
2. iOS API doesn't support information about satellites. We should probably return NULL instead of -1
3. should be fixed in Reset missing position data if missing #4670
4. network position provider satellites - we are reading the data correctly, looks like this issue is in the RTK. For testing I used Emlid RS+, Emlid flow app showed 24 satellites in view (not sure if we can find what satellites are used), corrections had 15 satellites in view. The actual data that was passed to Mergin Maps via NMEA GSV sentences informed us only about 8-10 satellites and all were used for positioning. That's what we showed users.