feat: remember per-satellite doppler offset in calculator

Store the last entered offset (kHz) per satellite in SharedPreferences
via SettingsRepo, and restore it when the linear transponder calculator
is shown for that satellite.

Follows the project's MVI/clean architecture:
- ISettingsRepo: getSatelliteOffset / setSatelliteOffset
- SettingsRepo: backed by SharedPreferences
- RadarState: calculatorOffsetKHz field
- RadarAction: ChangeCalculatorOffset
- RadarViewModel: loads offset on SelectTransmitter, saves on change
- CalculatorPage/DopplerFrequencyCalculator: receive offset via params
instead of accessing SharedPreferences directly from the UI layer.

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/SatelliteRepo.kt

@@ -34,6 +34,7 @@ import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.withContext
 import java.util.TimeZone
@@ -64,19 +65,23 @@ class SatelliteRepo(
     override suspend fun getRadiosWithId(id: Int) = localStorage.getRadiosWithId(id)
 
     override suspend fun initRepository() = withContext(dispatcher) {
-        settingsRepo.selectedIds.collect { selectedIds ->
-            _satellites.update { localStorage.getEntriesWithIds(selectedIds) }
-            val settings = settingsRepo.passesSettings.value
-            calculatePasses(
-                time = System.currentTimeMillis(),
-                hoursAhead = settings.hoursAhead,
-                minElevation = settings.minElevation,
-                aosStartMinute = settings.aosStartMinute,
-                aosEndMinute = settings.aosEndMinute,
-                invertAosTimeWindow = settings.invertAosTimeWindow,
-                modes = settingsRepo.selectedSatModes.value
-            )
-        }
+        combine(
+            settingsRepo.selectedIds,
+            settingsRepo.stationPosition
+        ) { selectedIds, _ -> selectedIds }
+            .collect { selectedIds ->
+                _satellites.update { localStorage.getEntriesWithIds(selectedIds) }
+                val settings = settingsRepo.passesSettings.value
+                calculatePasses(
+                    time = System.currentTimeMillis(),
+                    hoursAhead = settings.hoursAhead,
+                    minElevation = settings.minElevation,
+                    aosStartMinute = settings.aosStartMinute,
+                    aosEndMinute = settings.aosEndMinute,
+                    invertAosTimeWindow = settings.invertAosTimeWindow,
+                    modes = settingsRepo.selectedSatModes.value
+                )
+            }
     }
 
     override suspend fun getPosition(sat: OrbitalObject, pos: GeoPos, time: Long): OrbitalPos {

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/SettingsRepo.kt

@@ -37,6 +37,7 @@ import com.rtbishop.look4sat.core.domain.utility.round
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.update
+import org.json.JSONObject
 
 class SettingsRepo(
     private val locationManager: LocationManager,
@@ -417,5 +418,27 @@ class SettingsRepo(
         baudRate = preferences.getInt(keyRadioBaudRate, 4800),
         splitMode = preferences.getBoolean(keyRadioSplitMode, false)
     )
-    //endregion
+
+    private val keySatelliteOffsets = "satelliteOffsets"
+
+    override fun getSatelliteOffset(catnum: Int): String {
+        val json = preferences.getString(keySatelliteOffsets, "{}") ?: "{}"
+        return try {
+            JSONObject(json).optString(catnum.toString(), "")
+        } catch (e: Exception) {
+            ""
+        }
+    }
+
+    override fun setSatelliteOffset(catnum: Int, offset: String) {
+        val json = preferences.getString(keySatelliteOffsets, "{}") ?: "{}"
+        val updated = try {
+            val obj = JSONObject(json)
+            if (offset.isEmpty()) obj.remove(catnum.toString()) else obj.put(catnum.toString(), offset)
+            obj.toString()
+        } catch (e: Exception) {
+            """{"$catnum": "$offset"}"""
+        }
+        preferences.edit { putString(keySatelliteOffsets, updated) }
+    }
 }

core/data/src/test/java/com/rtbishop/look4sat/core/data/repository/DatabaseRepoTest.kt

@@ -213,6 +213,10 @@ private class FakeSettingsRepo(dataSources: DataSourcesSettings = defaultDataSou
     }
 
     override fun updateRadioControlSettings(settings: RadioControlSettings) = Unit
+
+    override fun getSatelliteOffset(catnum: Int): String = ""
+
+    override fun setSatelliteOffset(catnum: Int, offset: String) = Unit
 }
 
 private fun defaultDataSourcesSettings(): DataSourcesSettings {

core/data/src/test/java/com/rtbishop/look4sat/core/data/repository/SelectionRepoTest.kt

@@ -167,6 +167,10 @@ class SelectionRepoTest {
         override fun updateDataSourcesSettings(settings: DataSourcesSettings) = Unit
 
         override fun updateRadioControlSettings(settings: RadioControlSettings) = Unit
+
+        override fun getSatelliteOffset(catnum: Int): String = ""
+
+        override fun setSatelliteOffset(catnum: Int, offset: String) = Unit
     }
 }
 

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/repository/ISettingsRepo.kt

@@ -75,4 +75,9 @@ interface ISettingsRepo {
     val radioControlSettings: StateFlow<RadioControlSettings>
     fun updateRadioControlSettings(settings: RadioControlSettings)
     //endregion
+
+    //region # Per-satellite calculator offset settings
+    fun getSatelliteOffset(catnum: Int): String
+    fun setSatelliteOffset(catnum: Int, offset: String)
+    //endregion
 }

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/utility/DopplerFrequencyCalculator.kt

@@ -112,11 +112,30 @@ object DopplerFrequencyCalculator {
         val modes = listOfNotNull(transponder.downlinkMode, transponder.uplinkMode)
             .joinToString(separator = " ")
             .lowercase(Locale.ENGLISH)
-        val hasLinearName = info.contains("linear")
+        val hasLinearName = info.contains("linear") || info.contains(" lin") || info.startsWith("lin")
         val hasTransponderName = info.contains("transponder") || info.contains("transp") ||
                 info.contains("xponder") || info.contains("xpdr")
         val hasLinearMode = listOf("ssb", "usb", "lsb", "cw").any { modes.contains(it) }
 
-        return (hasLinearName && hasTransponderName) || (hasTransponderName && hasLinearMode)
+        return (hasLinearName && hasTransponderName) || (hasTransponderName && hasLinearMode) ||
+                (hasLinearName && hasLinearMode)
+    }
+
+    /**
+     * Removes duplicate transponder entries that describe the same physical
+     * transponder with different mode labels (e.g. SatNOGS lists AO-7's Mode A
+     * as both "Lin SSB" and "Lin CW", and JO-97's U/V transponder as both
+     * "CW Transponder" and "SSB Transponder").
+     *
+     * Entries sharing the same uplink/downlink frequency range are considered
+     * the same transponder. The non-CW entry is preferred because its invert
+     * flag is more reliable (e.g. JO-97's CW entry wrongly has invert=false).
+     */
+    fun deduplicateTransponders(radios: List<SatRadio>): List<SatRadio> {
+        return radios.groupBy { radio ->
+            listOf(radio.uplinkLow, radio.uplinkHigh, radio.downlinkLow, radio.downlinkHigh)
+        }.values.map { group ->
+            group.firstOrNull { it.downlinkMode?.equals("CW", ignoreCase = true) != true } ?: group.first()
+        }
     }
 }

core/domain/src/test/java/com/rtbishop/look4sat/core/domain/DopplerFrequencyCalculatorTest.kt

@@ -13,6 +13,7 @@ import org.junit.Test
 class DopplerFrequencyCalculatorTest {
 
     private fun linearTransponder(
+        uuid: String = "linear",
         upLow: Long = 145_000_000L,
         upHigh: Long = 145_500_000L,
         downLow: Long = 435_000_000L,
@@ -22,7 +23,7 @@ class DopplerFrequencyCalculatorTest {
         downlinkMode: String? = "USB",
         uplinkMode: String? = "LSB"
     ) = SatRadio(
-        uuid = "linear", info = info, isAlive = true,
+        uuid = uuid, info = info, isAlive = true,
         downlinkLow = downLow, downlinkHigh = downHigh,
         downlinkMode = downlinkMode, uplinkLow = upLow, uplinkHigh = upHigh,
         uplinkMode = uplinkMode, isInverted = inverted, catnum = 12345
@@ -72,11 +73,93 @@ class DopplerFrequencyCalculatorTest {
         assertFalse(DopplerFrequencyCalculator.isNamedLinearTransponder(driftingRangeEntry))
     }
 
+    @Test
+    fun isNamedLinearTransponder_returnsTrueForAbbreviatedLinName() {
+        // AO-7 style: "Mode V/A (A) Lin SSB" — "Lin" abbreviation, no "transponder" word
+        val ao7Entry = linearTransponder(info = "Mode V/A (A) Lin SSB", downlinkMode = "USB", uplinkMode = "USB")
+        assertTrue(DopplerFrequencyCalculator.isNamedLinearTransponder(ao7Entry))
+        val ao7CwEntry = linearTransponder(info = "Mode V/A (A) Lin CW", downlinkMode = "CW", uplinkMode = "CW")
+        assertTrue(DopplerFrequencyCalculator.isNamedLinearTransponder(ao7CwEntry))
+        val ao7ModeBEntry = linearTransponder(info = "Mode U/V (B) Lin", downlinkMode = "USB", uplinkMode = "LSB")
+        assertTrue(DopplerFrequencyCalculator.isNamedLinearTransponder(ao7ModeBEntry))
+    }
+
+    @Test
+    fun isNamedLinearTransponder_returnsTrueForLinearWithoutTransponderWord() {
+        // AO-73 style: "Mode U/V Linear" — has "Linear" but no "transponder"
+        val ao73Entry = linearTransponder(info = "Mode U/V Linear", downlinkMode = "USB", uplinkMode = "LSB")
+        assertTrue(DopplerFrequencyCalculator.isNamedLinearTransponder(ao73Entry))
+    }
+
+    @Test
+    fun isNamedLinearTransponder_returnsFalseForDownlinkContainingLinInsideWord() {
+        // "Downlink" contains "lin" but is not a linear-transponder name
+        val downlinkEntry = linearTransponder(info = "Mode U Downlink", downlinkMode = "FM", uplinkMode = "FM")
+        assertFalse(DopplerFrequencyCalculator.isNamedLinearTransponder(downlinkEntry))
+    }
+
     @Test
     fun isNamedLinearTransponder_returnsFalseForFmRepeater() {
         assertFalse(DopplerFrequencyCalculator.isNamedLinearTransponder(fmTransponder()))
     }
 
+    @Test
+    fun deduplicateTransponders_mergesSameFrequencyRange() {
+        // AO-7's Mode A: same range, SSB and CW entries
+        val ssb = linearTransponder(
+            uuid = "ssb-uuid", info = "Mode V/A (A) Lin SSB",
+            downlinkMode = "USB", uplinkMode = "USB"
+        )
+        val cw = linearTransponder(
+            uuid = "cw-uuid", info = "Mode V/A (A) Lin CW",
+            downlinkMode = "CW", uplinkMode = "CW"
+        )
+        val modeB = linearTransponder(
+            uuid = "modeb-uuid", info = "Mode U/V (B) Lin",
+            upLow = 432_125_000L, upHigh = 432_175_000L,
+            downLow = 145_925_000L, downHigh = 145_975_000L,
+            downlinkMode = "USB", uplinkMode = "LSB"
+        )
+        val result = DopplerFrequencyCalculator.deduplicateTransponders(listOf(ssb, cw, modeB))
+        assertEquals(2, result.size)
+        // SSB entry should be preferred over CW (same range)
+        assertEquals("ssb-uuid", result[0].uuid)
+        assertEquals("modeb-uuid", result[1].uuid)
+    }
+
+    @Test
+    fun deduplicateTransponders_prefersNonCwEntry() {
+        // JO-97: CW entry has invert=false (wrong), SSB has invert=true (correct)
+        val cw = linearTransponder(
+            uuid = "cw-uuid", info = "U/V CW Transponder",
+            downlinkMode = "CW", uplinkMode = "CW",
+            upLow = 435_100_000L, upHigh = 435_120_000L,
+            downLow = 145_855_000L, downHigh = 145_875_000L
+        )
+        val ssb = linearTransponder(
+            uuid = "ssb-uuid", info = "U/V SSB Transponder",
+            downlinkMode = "USB", uplinkMode = "LSB",
+            upLow = 435_100_000L, upHigh = 435_120_000L,
+            downLow = 145_855_000L, downHigh = 145_875_000L,
+            inverted = true
+        )
+        val result = DopplerFrequencyCalculator.deduplicateTransponders(listOf(cw, ssb))
+        assertEquals(1, result.size)
+        assertEquals("ssb-uuid", result[0].uuid)
+        // Verify the correct invert flag is preserved
+        assertTrue(result[0].isInverted)
+    }
+
+    @Test
+    fun deduplicateTransponders_preservesUniqueEntries() {
+        val t1 = linearTransponder(uuid = "t1", upLow = 145_000_000L, upHigh = 145_500_000L,
+            downLow = 435_000_000L, downHigh = 435_500_000L)
+        val t2 = linearTransponder(uuid = "t2", upLow = 435_000_000L, upHigh = 435_500_000L,
+            downLow = 145_000_000L, downHigh = 145_500_000L)
+        val result = DopplerFrequencyCalculator.deduplicateTransponders(listOf(t1, t2))
+        assertEquals(2, result.size)
+    }
+
     @Test
     fun computeUplinkFromDownlink_linear_noDoppler() {
         val xpdr = linearTransponder()

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarScreen.kt

@@ -198,7 +198,8 @@ private fun PagerCard(
                         transceivers = uiState.transceivers.transmitters,
                         selectedUuid = uiState.transceivers.selectedUuid,
                         orbitalPos = uiState.orbitalPos,
-                        onAction = onAction
+                        onAction = onAction,
+                        calculatorOffsetKHz = uiState.calculatorOffsetKHz
                     )
                     RadarPage.Sstv -> SstvPage(
                         sstv = uiState.sstv,

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarState.kt

@@ -63,7 +63,8 @@ data class RadarState(
     val moonPosition: CelestialComputer.MoonPosition? = null,
     val transceivers: TransceiverSubState = TransceiverSubState(),
     val radioControl: RadioControlSubState = RadioControlSubState(),
-    val sstv: SstvSubState = SstvSubState()
+    val sstv: SstvSubState = SstvSubState(),
+    val calculatorOffsetKHz: String = ""
 )
 
 enum class SstvStatus { Idle, Recording }
@@ -97,4 +98,7 @@ sealed interface RadarAction {
     data object SstvReset : RadarAction
     data class SstvSelectMode(val modeName: String) : RadarAction
     data class SstvPermissionResult(val granted: Boolean) : RadarAction
+
+    // Calculator actions
+    data class ChangeCalculatorOffset(val offsetKHz: String) : RadarAction
 }

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarViewModel.kt

@@ -260,7 +260,17 @@ class RadarViewModel(
                 // Compute toggle state before the update so we don't read post-update value
                 val isTogglingOff = _uiState.value.transceivers.selectedUuid == action.uuid
                 val newUuid = if (isTogglingOff) null else action.uuid
-                _uiState.update { it.copy(transceivers = it.transceivers.copy(selectedUuid = newUuid)) }
+                // Load the saved offset for the newly selected satellite
+                val offsetKHz = if (!isTogglingOff) {
+                    transponders.find { it.uuid == action.uuid }
+                        ?.catnum?.let { settingsRepo.getSatelliteOffset(it) } ?: ""
+                } else ""
+                _uiState.update {
+                    it.copy(
+                        transceivers = it.transceivers.copy(selectedUuid = newUuid),
+                        calculatorOffsetKHz = offsetKHz
+                    )
+                }
                 // Only update the tracking service when selecting a different transponder to
                 // avoid resetting a user-adjusted TX base on re-expand
                 if (!isTogglingOff) {
@@ -309,6 +319,15 @@ class RadarViewModel(
                 sstvDecoder?.clearPixels()
                 _uiState.update { it.copy(sstv = it.sstv.copy(currentFrame = null)) }
             }
+            is RadarAction.ChangeCalculatorOffset -> {
+                val catnum = _uiState.value.transceivers.selectedUuid?.let { uuid ->
+                    transponders.find { it.uuid == uuid }?.catnum
+                }
+                if (catnum != null) {
+                    settingsRepo.setSatelliteOffset(catnum, action.offsetKHz)
+                }
+                _uiState.update { it.copy(calculatorOffsetKHz = action.offsetKHz) }
+            }
         }
     }
 

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/TransceiversPage.kt

@@ -21,14 +21,18 @@ import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.expandVertically
 import androidx.compose.animation.shrinkVertically
 import androidx.compose.foundation.background
+import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.interaction.MutableInteractionSource
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.FlowRow
+import androidx.compose.foundation.layout.IntrinsicSize
+import androidx.compose.foundation.layout.PaddingValues
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
@@ -39,16 +43,20 @@ import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.text.BasicTextField
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material3.FilterChip
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Slider
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
@@ -59,6 +67,7 @@ import androidx.compose.ui.draw.rotate
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.text.style.TextAlign
@@ -68,6 +77,7 @@ import androidx.compose.ui.unit.sp
 import com.rtbishop.look4sat.core.domain.model.SatRadio
 import com.rtbishop.look4sat.core.domain.predict.OrbitalPos
 import com.rtbishop.look4sat.core.domain.utility.DopplerFrequencyCalculator
+import com.rtbishop.look4sat.core.domain.utility.TransponderMapper
 import com.rtbishop.look4sat.core.presentation.CardButton
 import com.rtbishop.look4sat.core.presentation.R
 import com.rtbishop.look4sat.core.presentation.formatFrequency
@@ -118,10 +128,12 @@ fun CalculatorPage(
     selectedUuid: String?,
     orbitalPos: OrbitalPos?,
     onAction: (RadarAction) -> Unit,
+    calculatorOffsetKHz: String = "",
     modifier: Modifier = Modifier
 ) {
     val calculatorTransceivers = remember(transceivers) {
         transceivers.filter(DopplerFrequencyCalculator::isNamedLinearTransponder)
+            .let(DopplerFrequencyCalculator::deduplicateTransponders)
     }
     val selectedTransceiver = remember(calculatorTransceivers, selectedUuid) {
         calculatorTransceivers.firstOrNull { it.uuid == selectedUuid }
@@ -166,9 +178,11 @@ fun CalculatorPage(
         }
 
         item {
-            DopplerCalculatorPanel(
+            DopplerFrequencyCalculator(
                 transponder = selectedTransceiver,
                 orbitalPos = orbitalPos,
+                offsetKHz = calculatorOffsetKHz,
+                onOffsetChange = { onAction(RadarAction.ChangeCalculatorOffset(it)) },
                 modifier = Modifier.fillMaxWidth()
             )
         }
@@ -504,108 +518,362 @@ private fun ExpandedRadioControl(
     }
 }
 
+private enum class EditedField { TX, PASSBAND, RX }
+
 @Composable
-private fun DopplerCalculatorPanel(
+private fun DopplerFrequencyCalculator(
     transponder: SatRadio,
     orbitalPos: OrbitalPos?,
+    offsetKHz: String = "",
+    onOffsetChange: (String) -> Unit = {},
     modifier: Modifier = Modifier
 ) {
     if (orbitalPos == null || !DopplerFrequencyCalculator.isLinearTransponder(transponder)) return
 
-    var txInputMHz by remember(transponder.uuid) { mutableStateOf("") }
-    var rxInputMHz by remember(transponder.uuid) { mutableStateOf("") }
-    var offsetKHz by remember(transponder.uuid) { mutableStateOf("") }
-    var lastEditedBy by remember(transponder.uuid) { mutableStateOf(EditedField.TX) }
+    var lastEditedField by remember { mutableStateOf(EditedField.TX) }
+    var txFrequencyHz by remember { mutableStateOf(0L) }
+    var rxFrequencyHz by remember { mutableStateOf(0L) }
+    var passbandPosition by remember { mutableStateOf(0.5f) }
+    var stepSizeKHz by remember { mutableIntStateOf(1) }
 
-    fun offsetHz(text: String): Long = text.toDoubleOrNull()?.let { (it * 1000).toLong() } ?: 0L
-    fun formatHz(hz: Long): String = String.format(Locale.ENGLISH, "%.6f", hz / 1_000_000.0)
-    fun mhzToHz(text: String): Long? = text.toDoubleOrNull()
-        ?.takeIf { it > 0.0 }
-        ?.let { (it * 1_000_000).toLong() }
+    val offsetHz = offsetKHz.toDoubleOrNull()?.let { it * 1000 }?.toLong() ?: 0L
 
-    fun calculateDownlink(txText: String, offsetText: String): String? {
-        val txHz = mhzToHz(txText) ?: return null
-        return DopplerFrequencyCalculator.computeDownlinkFromUplinkWithOffset(
-            uplinkHz = txHz,
-            transponder = transponder,
-            orbitalPos = orbitalPos,
-            offsetHz = offsetHz(offsetText)
-        )?.let(::formatHz)
+    val txLow = transponder.uplinkLow ?: return
+    val txHigh = transponder.uplinkHigh ?: return
+    val rxLow = transponder.downlinkLow ?: return
+    val rxHigh = transponder.downlinkHigh ?: return
+    val txRange = txHigh - txLow
+    val rxRange = rxHigh - rxLow
+    if (txRange <= 0L || rxRange <= 0L) return
+
+    // 原始转发器值（逆转多普勒），用于 passband 映射计算
+    val rawTxLow = orbitalPos.getDownlinkFreq(txLow)
+    val rawTxHigh = orbitalPos.getDownlinkFreq(txHigh)
+    val rawRxLow = orbitalPos.getUplinkFreq(rxLow)
+    val rawRxHigh = orbitalPos.getUplinkFreq(rxHigh)
+    val rawTxRange = rawTxHigh - rawTxLow
+    val rawRxRange = rawRxHigh - rawRxLow
+    val rawTransponder = transponder.copy(
+        uplinkLow = rawTxLow, uplinkHigh = rawTxHigh,
+        downlinkLow = rawRxLow, downlinkHigh = rawRxHigh
+    )
+
+    // 初始化
+    LaunchedEffect(Unit) {
+        if (txFrequencyHz == 0L) {
+            txFrequencyHz = txLow + txRange / 2
+            rxFrequencyHz = DopplerFrequencyCalculator.computeDownlinkFromUplinkWithOffset(
+                txFrequencyHz, rawTransponder, orbitalPos, offsetHz
+            ) ?: (rxLow + rxRange / 2)
+        }
     }
 
-    fun calculateUplink(rxText: String, offsetText: String): String? {
-        val rxHz = mhzToHz(rxText) ?: return null
-        return DopplerFrequencyCalculator.computeUplinkFromDownlinkWithOffset(
-            downlinkHz = rxHz,
-            transponder = transponder,
-            orbitalPos = orbitalPos,
-            offsetHz = offsetHz(offsetText)
-        )?.let(::formatHz)
+    // 实时重算：卫星移动时，锚点侧不变，重算另一侧
+    LaunchedEffect(orbitalPos) {
+        if (lastEditedField == EditedField.TX) {
+            // TX 是锚点，不变；重算 RX
+            rxFrequencyHz = DopplerFrequencyCalculator.computeDownlinkFromUplinkWithOffset(
+                txFrequencyHz, rawTransponder, orbitalPos, offsetHz
+            ) ?: rxFrequencyHz
+        } else if (lastEditedField == EditedField.RX) {
+            // RX 是锚点，不变；重算 TX
+            txFrequencyHz = DopplerFrequencyCalculator.computeUplinkFromDownlinkWithOffset(
+                rxFrequencyHz, rawTransponder, orbitalPos, offsetHz
+            ) ?: txFrequencyHz
+        } else if (lastEditedField == EditedField.PASSBAND) {
+            // 相对位置不变（passbandPosition），TX 用地面频率，RX 经 Transceiver 完整路径计算
+            txFrequencyHz = txLow + (passbandPosition * txRange).toLong()
+            rxFrequencyHz = DopplerFrequencyCalculator.computeDownlinkFromUplinkWithOffset(
+                txFrequencyHz, rawTransponder, orbitalPos, offsetHz
+            ) ?: rxFrequencyHz
+        }
     }
 
-    LaunchedEffect(orbitalPos, transponder.uuid) {
-        if (lastEditedBy == EditedField.TX) {
-            calculateDownlink(txInputMHz, offsetKHz)?.let { rxInputMHz = it }
-        } else {
-            calculateUplink(rxInputMHz, offsetKHz)?.let { txInputMHz = it }
+    val txSliderValue = if (lastEditedField == EditedField.PASSBAND) {
+        passbandPosition
+    } else {
+        ((txFrequencyHz - txLow).toFloat() / txRange).coerceIn(0f, 1f)
+    }
+    val rxSliderValue = if (lastEditedField == EditedField.PASSBAND) {
+        ((rxFrequencyHz - rxLow).toFloat() / rxRange).coerceIn(0f, 1f)
+    } else {
+        ((rxFrequencyHz - rxLow).toFloat() / rxRange).coerceIn(0f, 1f)
+    }
+
+    fun updateTx(newTxHz: Long) {
+        when (lastEditedField) {
+            EditedField.PASSBAND -> {
+                // Passband 模式：滑块位置 → passbandPosition → 地面频率，RX 经 Transceiver 计算
+                val pos = ((newTxHz - txLow).toFloat() / txRange).coerceIn(0f, 1f)
+                passbandPosition = pos
+                txFrequencyHz = txLow + (pos * txRange).toLong()
+                rxFrequencyHz = DopplerFrequencyCalculator.computeDownlinkFromUplinkWithOffset(
+                    txFrequencyHz, rawTransponder, orbitalPos, offsetHz
+                ) ?: rxFrequencyHz
+            }
+            else -> {
+                txFrequencyHz = newTxHz.coerceIn(txLow, txHigh)
+                rxFrequencyHz = DopplerFrequencyCalculator.computeDownlinkFromUplinkWithOffset(
+                    txFrequencyHz, rawTransponder, orbitalPos, offsetHz
+                ) ?: rxFrequencyHz
+            }
+        }
+    }
+
+    fun updateRx(newRxHz: Long) {
+        when (lastEditedField) {
+            EditedField.PASSBAND -> {
+                // Passband 模式：从 RX 反推 TX 位置，TX 用地面频率
+                val pos = ((newRxHz - rxLow).toFloat() / rxRange).coerceIn(0f, 1f)
+                val txFromRx = TransponderMapper.mapDownlinkToUplink(newRxHz, rawTransponder)
+                passbandPosition = if (txFromRx != null) {
+                    ((txFromRx - rawTxLow).toFloat() / rawTxRange).coerceIn(0f, 1f)
+                } else pos
+                txFrequencyHz = txLow + (passbandPosition * txRange).toLong()
+                rxFrequencyHz = DopplerFrequencyCalculator.computeDownlinkFromUplinkWithOffset(
+                    txFrequencyHz, rawTransponder, orbitalPos, offsetHz
+                ) ?: rxFrequencyHz
+            }
+            else -> {
+                rxFrequencyHz = newRxHz.coerceIn(rxLow, rxHigh)
+                txFrequencyHz = DopplerFrequencyCalculator.computeUplinkFromDownlinkWithOffset(
+                    rxFrequencyHz, rawTransponder, orbitalPos, offsetHz
+                ) ?: txFrequencyHz
+            }
         }
     }
 
     Column(
-        modifier = modifier,
-        verticalArrangement = Arrangement.spacedBy(8.dp)
+        modifier = modifier.fillMaxWidth().padding(top = 16.dp),
+        verticalArrangement = Arrangement.spacedBy(12.dp)
     ) {
-        OutlinedTextField(
-            value = offsetKHz,
-            onValueChange = { newValue ->
-                offsetKHz = newValue
-                if (lastEditedBy == EditedField.TX) {
-                    calculateDownlink(txInputMHz, newValue)?.let { rxInputMHz = it }
-                } else {
-                    calculateUplink(rxInputMHz, newValue)?.let { txInputMHz = it }
+            Row(
+                modifier = Modifier.fillMaxWidth().height(IntrinsicSize.Min),
+                verticalAlignment = Alignment.CenterVertically,
+                horizontalArrangement = Arrangement.spacedBy(6.dp)
+            ) {
+                // 左半边: TX + RX 按钮
+                Row(
+                    modifier = Modifier.weight(1f),
+                    horizontalArrangement = Arrangement.spacedBy(4.dp),
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    FilterChip(
+                        selected = lastEditedField == EditedField.TX,
+                        onClick = {
+                            when (lastEditedField) {
+                                EditedField.TX -> {
+                                    passbandPosition = ((txFrequencyHz - txLow).toFloat() / txRange).coerceIn(0f, 1f)
+                                    lastEditedField = EditedField.PASSBAND
+                                    rxFrequencyHz = DopplerFrequencyCalculator.computeDownlinkFromUplinkWithOffset(
+                                        txFrequencyHz, rawTransponder, orbitalPos, offsetHz
+                                    ) ?: rxFrequencyHz
+                                }
+                                EditedField.PASSBAND -> { lastEditedField = EditedField.TX }
+                                else -> { lastEditedField = EditedField.TX }
+                            }
+                        },
+                        label = {
+                            Text("TX", fontSize = 13.sp, textAlign = TextAlign.Center,
+                                modifier = Modifier.fillMaxWidth())
+                        },
+                        modifier = Modifier.weight(1f).fillMaxHeight()
+                    )
+                    FilterChip(
+                        selected = lastEditedField == EditedField.RX,
+                        onClick = {
+                            when (lastEditedField) {
+                                EditedField.RX -> {
+                                    txFrequencyHz = DopplerFrequencyCalculator.computeUplinkFromDownlinkWithOffset(
+                                        rxFrequencyHz, rawTransponder, orbitalPos, offsetHz
+                                    ) ?: txFrequencyHz
+                                    passbandPosition = ((txFrequencyHz - txLow).toFloat() / txRange).coerceIn(0f, 1f)
+                                    lastEditedField = EditedField.PASSBAND
+                                }
+                                EditedField.PASSBAND -> {
+                                    lastEditedField = EditedField.RX
+                                    txFrequencyHz = DopplerFrequencyCalculator.computeUplinkFromDownlinkWithOffset(
+                                        rxFrequencyHz, rawTransponder, orbitalPos, offsetHz
+                                    ) ?: txFrequencyHz
+                                }
+                                else -> { lastEditedField = EditedField.RX }
+                            }
+                        },
+                        label = {
+                            Text("RX", fontSize = 13.sp, textAlign = TextAlign.Center,
+                                modifier = Modifier.fillMaxWidth())
+                        },
+                        modifier = Modifier.weight(1f).fillMaxHeight()
+                    )
                 }
-            },
-            label = { Text(stringResource(R.string.radar_doppler_offset_hint)) },
-            singleLine = true,
-            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Text),
-            modifier = Modifier.fillMaxWidth()
-        )
+                // 右半边: Offset 输入框（带细线边框）
+                Box(
+                    modifier = Modifier
+                        .weight(1f)
+                        .height(48.dp)
+                        .border(1.dp, MaterialTheme.colorScheme.outline, MaterialTheme.shapes.small),
+                    contentAlignment = Alignment.Center
+                ) {
+                    BasicTextField(
+                        value = offsetKHz,
+                        onValueChange = onOffsetChange,
+                        singleLine = true,
+                        textStyle = TextStyle(
+                            fontSize = 16.sp,
+                            textAlign = TextAlign.Center,
+                            color = MaterialTheme.colorScheme.onSurface
+                        ),
+                        decorationBox = { innerTextField ->
+                            if (offsetKHz.isEmpty()) {
+                                Text(
+                                    text = "Offset (kHz)",
+                                    fontSize = 16.sp,
+                                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                                )
+                            }
+                            innerTextField()
+                        }
+                    )
+                }
+            }
 
-        Row(
-            horizontalArrangement = Arrangement.spacedBy(8.dp),
-            modifier = Modifier.fillMaxWidth()
-        ) {
-            OutlinedTextField(
-                value = txInputMHz,
-                onValueChange = { newValue ->
-                    txInputMHz = newValue
-                    lastEditedBy = EditedField.TX
-                    rxInputMHz = calculateDownlink(newValue, offsetKHz) ?: if (newValue.isEmpty()) "" else rxInputMHz
-                },
-                label = { Text(stringResource(R.string.radar_doppler_tx_hint)) },
-                singleLine = true,
-                keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
-                modifier = Modifier.weight(1f)
+            // TX 行
+            Column(modifier = Modifier.fillMaxWidth()) {
+                Row(verticalAlignment = Alignment.CenterVertically) {
+                    OutlinedButton(
+                        onClick = { updateTx(txFrequencyHz - stepSizeKHz * 1000L) },
+                        modifier = Modifier.width(32.dp).height(28.dp),
+                        contentPadding = PaddingValues(0.dp),
+                        shape = MaterialTheme.shapes.extraSmall
+                    ) { Text("−", fontSize = 14.sp) }
+
+                    Slider(
+                        value = txSliderValue,
+                        onValueChange = { norm ->
+                            val rawFreq = txLow + (txRange * norm).toLong()
+                            val snapped = ((rawFreq + 500) / 1000L) * 1000L
+                            updateTx(snapped.coerceIn(txLow, txHigh))
+                        },
+                        valueRange = 0f..1f,
+                        modifier = Modifier.weight(1f).height(20.dp).padding(horizontal = 4.dp)
+                    )
+
+                    OutlinedButton(
+                        onClick = { updateTx(txFrequencyHz + stepSizeKHz * 1000L) },
+                        modifier = Modifier.width(32.dp).height(28.dp),
+                        contentPadding = PaddingValues(0.dp),
+                        shape = MaterialTheme.shapes.extraSmall
+                    ) { Text("+", fontSize = 14.sp) }
+                }
+                Row(
+                    modifier = Modifier.fillMaxWidth().padding(horizontal = 4.dp),
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    Text(
+                        text = String.format(Locale.ENGLISH, "%.4f", txLow / 1_000_000.0),
+                        fontSize = 12.sp,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.weight(1f)
+                    )
+                    Row(
+                        verticalAlignment = Alignment.CenterVertically,
+                        horizontalArrangement = Arrangement.Center
+                    ) {
+                        Text(
+                            text = String.format(Locale.ENGLISH, "%.6f", txFrequencyHz / 1_000_000.0),
+                            fontSize = 20.sp,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.primary
+                        )
+                        Text(
+                            text = " MHz",
+                            fontSize = 20.sp,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.primary
+                        )
+                    }
+                    Text(
+                        text = String.format(Locale.ENGLISH, "%.4f", txHigh / 1_000_000.0),
+                        fontSize = 12.sp,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.weight(1f),
+                        textAlign = TextAlign.End
+                    )
+                }
+            }
+
+            HorizontalDivider(
+                thickness = 0.5.dp,
+                color = MaterialTheme.colorScheme.outline.copy(alpha = 0.3f)
             )
 
-            OutlinedTextField(
-                value = rxInputMHz,
-                onValueChange = { newValue ->
-                    rxInputMHz = newValue
-                    lastEditedBy = EditedField.RX
-                    txInputMHz = calculateUplink(newValue, offsetKHz) ?: if (newValue.isEmpty()) "" else txInputMHz
-                },
-                label = { Text(stringResource(R.string.radar_doppler_rx_hint)) },
-                singleLine = true,
-                keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
-                modifier = Modifier.weight(1f)
-            )
+            // RX 行
+            Column(modifier = Modifier.fillMaxWidth()) {
+                Row(verticalAlignment = Alignment.CenterVertically) {
+                    OutlinedButton(
+                        onClick = { updateRx(rxFrequencyHz - stepSizeKHz * 1000L) },
+                        modifier = Modifier.width(32.dp).height(28.dp),
+                        contentPadding = PaddingValues(0.dp),
+                        shape = MaterialTheme.shapes.extraSmall
+                    ) { Text("−", fontSize = 14.sp) }
+
+                    Slider(
+                        value = rxSliderValue,
+                        onValueChange = { norm ->
+                            val rawFreq = rxLow + (rxRange * norm).toLong()
+                            val snapped = ((rawFreq + 500) / 1000L) * 1000L
+                            updateRx(snapped.coerceIn(rxLow, rxHigh))
+                        },
+                        valueRange = 0f..1f,
+                        modifier = Modifier.weight(1f).height(20.dp).padding(horizontal = 4.dp)
+                    )
+
+                    OutlinedButton(
+                        onClick = { updateRx(rxFrequencyHz + stepSizeKHz * 1000L) },
+                        modifier = Modifier.width(32.dp).height(28.dp),
+                        contentPadding = PaddingValues(0.dp),
+                        shape = MaterialTheme.shapes.extraSmall
+                    ) { Text("+", fontSize = 14.sp) }
+                }
+                Row(
+                    modifier = Modifier.fillMaxWidth().padding(horizontal = 4.dp),
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    Text(
+                        text = String.format(Locale.ENGLISH, "%.4f", rxLow / 1_000_000.0),
+                        fontSize = 12.sp,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.weight(1f)
+                    )
+                    Row(
+                        verticalAlignment = Alignment.CenterVertically,
+                        horizontalArrangement = Arrangement.Center
+                    ) {
+                        Text(
+                            text = String.format(Locale.ENGLISH, "%.6f", rxFrequencyHz / 1_000_000.0),
+                            fontSize = 20.sp,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.primary
+                        )
+                        Text(
+                            text = " MHz",
+                            fontSize = 20.sp,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.primary
+                        )
+                    }
+                    Text(
+                        text = String.format(Locale.ENGLISH, "%.4f", rxHigh / 1_000_000.0),
+                        fontSize = 12.sp,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.weight(1f),
+                        textAlign = TextAlign.End
+                    )
+                }
+            }
         }
-    }
 }
 
-private enum class EditedField { TX, RX }
-
 @Composable
 private fun FrequencyText(frequency: Long?, modifier: Modifier = Modifier) {
     val text = frequency?.let {
@@ -629,3 +897,4 @@ private fun transceiverTitle(radio: SatRadio): String {
 
 private val FREQ_ADJUSTMENTS =
     listOf(-10_000L to "-10k", -1_000L to "-1k", -100L to "-100", 100L to "+100", 1_000L to "+1k", 10_000L to "+10k")
+