mckero a37fb8f773 feat(domain): support 6/8/10-char Maidenhead grid square conversion
Port the 8-char (4-pair) Maidenhead grid algorithm from the
"QTH定位器 2.0" app (com.us1pm.gridsquarelocator) into QthConverter
so locator precision matches common grid tools instead of being
truncated to 6 chars.

Previously positionToQth() emitted only 6-char locators and
qthToPosition() discarded everything past the 6th character via
take(6), losing the finer 30" x 15" resolution carried by 8-char
grid squares.

What changed:
- positionToQth(lat, lon, precision = 8) now emits 8-char locators
  by default; precision = 6 / 10 available for backwards
  compatibility and maximum resolution (1.25" x 0.625").
- qthToPosition() parses 6/8/10-char locators and returns the center
  of the finest encoded cell (30" x 15" for 8-char, 1.25" x 0.625"
  for 10-char) instead of the 6-char cell center.
- Locator validation regex tightened: 6/8/10 chars accepted,
  4-char strings like "JN58" are now rejected as invalid.
- Boundary clamping added so lat = 90 / lon = 180 no longer overflow
  the A-R / 0-9 / a-x alphabet (previously produced invalid chars).

Also fixed a pre-existing compile error in RadarView.kt: a delegated
property was assigned after declaration ("by" on an already declared
val). Converted the sweep angle to an if/else expression.

Verification:
- QthConverterTest extended to 5 test cases covering 6/8/10-char
  roundtrips, invalid input, boundary coordinates and roundtrip
  stability.
- Cross-checked against a Python reference model of the decompiled
  APK algorithm: 20k random roundtrips at 8 and 10 chars, 0 failures.
- :core:domain:test green; :app:compileDebugKotlin passes.
2026-08-03 07:25:31 +00:00

Look4Sat: Satellite tracker

Look4Sat CI

Get it on Google Play Get it on F-Droid

Radio satellite tracker and pass predictor for Android, inspired by Gpredict

Track satellite passes with ease!

Thanks to Celestrak and SatNOGS you have access to over 9000 active satellites.
You can search the entire database by NORAD Catalog Number or the satellite's name.

Orbital positions and passes are calculated relative to your location.
To get reliable data make sure to set the station position via the app Settings.

The application is built using Kotlin, Coroutines, Jetpack Compose and Navigation.
It is now and always will be completely ad-free and open-source.

Main features:

  • Predicting satellite positions and passes for up to 10 days
  • Showing the list of currently active and upcoming satellite passes
  • Showing the active pass progress, polar trajectory and transceivers info
  • Showing the satellite positional data, footprint and ground track on the map
  • Custom TLE satellite data import is available via Three Line Element .txt files
  • Offline first: calculations are made offline. Weekly TLE data update is recommended.

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