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Filter untracked GNSS satellites and mark unknown geometry #26

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Merged
thomasbuilds merged 1 commit into from
Jul 19, 2026
Merged

Filter untracked GNSS satellites and mark unknown geometry #26

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21 changes: 16 additions & 5 deletions app/src/main/java/dev/thomasbuilds/spectre/scanner/gnss/GnssScanner.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,8 @@ class GnssScanner(
object : GnssStatus.Callback() {
override fun onSatelliteStatusChanged(status: GnssStatus) {
val now = SystemClock.elapsedRealtime()
// The HAL also lists satellites it is merely searching for, reporting C/N0 as 0 with no
// flag to tell them apart. Only tracked satellites are received signals; keep those.
val raw =
List(status.satelliteCount) { i ->
RawSatelliteEntry(
Expand All @@ -100,7 +102,7 @@ class GnssScanner(
hasAlmanac = status.hasAlmanacData(i),
carrierHz = if (status.hasCarrierFrequencyHz(i)) status.getCarrierFrequencyHz(i) else null
)
}
}.filter { it.cn0DbHz > 0f || it.usedInFix }

val rateUnavailable =
!measurementsSupported || (!driftSeen && syncedNoDriftEpochs >= SYNCED_NO_DRIFT_EPOCHS)
Expand All @@ -109,9 +111,12 @@ class GnssScanner(
val bandsByCn0 = group.sortedByDescending { it.cn0DbHz }
val bestBand = bandsByCn0.first()

// Elevation/azimuth stay at 0 until the receiver knows the orbit; exactly (0°, 0°)
// from a live satellite means "not computed yet", not a bearing.
val geometryKnown = bestBand.elevationDeg != 0f || bestBand.azimuthDeg != 0f
val phoneLoc = lastLocation
val subPoint =
phoneLoc?.let {
phoneLoc?.takeIf { geometryKnown }?.let {
CelestialGeometry.compute(
phoneLatDeg = it.latitude,
phoneLonDeg = it.longitude,
Expand All @@ -125,8 +130,8 @@ class GnssScanner(
val details =
buildList {
add(DetailEntry("Constellation", bestBand.constellation.label))
add(DetailEntry("Elevation", "${"%.1f".format(bestBand.elevationDeg)}°"))
add(DetailEntry("Azimuth", "${"%.1f".format(bestBand.azimuthDeg)}°"))
add(DetailEntry("Elevation", if (geometryKnown) "${"%.1f".format(bestBand.elevationDeg)}°" else "Unknown"))
add(DetailEntry("Azimuth", if (geometryKnown) "${"%.1f".format(bestBand.azimuthDeg)}°" else "Unknown"))
val rateText =
if (rateUnavailable) {
"Unavailable"
Expand All @@ -144,7 +149,13 @@ class GnssScanner(
add(DetailEntry("Slant range", "${"%.0f".format(subPoint.slantRangeM / 1000.0)} km"))
add(DetailEntry("Orbital altitude", "${"%.0f".format(subPoint.altitudeAboveEarthM / 1000.0)} km"))
} else {
add(DetailEntry("Position", if (phoneLoc == null) "Pending" else "Below horizon"))
val positionText =
when {
!geometryKnown -> "Unknown"
phoneLoc == null -> "Pending"
else -> "Below horizon"
}
add(DetailEntry("Position", positionText))
}
add(DetailEntry("Ephemeris data", if (bestBand.hasEphemeris) "Yes" else "No"))
add(DetailEntry("Almanac data", if (bestBand.hasAlmanac) "Yes" else "No"))
Expand Down
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