Added SSTV image decoding functionality to RadarScreen

app/src/main/AndroidManifest.xml

@@ -11,6 +11,7 @@
     <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
     <uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.RECORD_AUDIO" />
 
     <application
         android:name=".MainApplication"

core/data/src/main/AndroidManifest.xml

@@ -11,5 +11,6 @@
     <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
     <uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.RECORD_AUDIO" />
 
 </manifest>

core/data/src/main/java/com/rtbishop/look4sat/core/data/injection/MainContainer.kt

@@ -1,3 +1,20 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package com.rtbishop.look4sat.core.data.injection
 
 import android.bluetooth.BluetoothManager
@@ -20,6 +37,8 @@ import com.rtbishop.look4sat.core.data.repository.SettingsRepo
 import com.rtbishop.look4sat.core.data.source.LocalSource
 import com.rtbishop.look4sat.core.data.source.RemoteSource
 import com.rtbishop.look4sat.core.data.usecase.AddToCalendar
+import com.rtbishop.look4sat.core.data.usecase.AudioCapture
+import com.rtbishop.look4sat.core.data.usecase.SaveImage
 import com.rtbishop.look4sat.core.data.usecase.ShowToast
 import com.rtbishop.look4sat.core.domain.repository.IDatabaseRepo
 import com.rtbishop.look4sat.core.domain.repository.IMainContainer
@@ -33,6 +52,8 @@ import com.rtbishop.look4sat.core.domain.repository.ISettingsRepo
 import com.rtbishop.look4sat.core.domain.source.ILocalSource
 import com.rtbishop.look4sat.core.domain.source.IRemoteSource
 import com.rtbishop.look4sat.core.domain.usecase.IAddToCalendar
+import com.rtbishop.look4sat.core.domain.usecase.IAudioCapture
+import com.rtbishop.look4sat.core.domain.usecase.ISaveImage
 import com.rtbishop.look4sat.core.domain.usecase.IShowToast
 import com.rtbishop.look4sat.core.domain.utility.DataParser
 import kotlinx.coroutines.CoroutineExceptionHandler
@@ -59,6 +80,10 @@ class MainContainer(private val context: Context) : IMainContainer {
 
     override fun provideShowToast(): IShowToast = ShowToast(context)
 
+    override fun provideAudioCapture(): IAudioCapture = AudioCapture()
+
+    override fun provideSaveImage(): ISaveImage = SaveImage(context)
+
     override fun provideBluetoothReporter(): IReporter {
         val manager = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
         val rc = settingsRepo.rcSettings.value

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

@@ -81,6 +81,7 @@ class SettingsRepo(
     private val keyUpdateTimestamp = "updateTimestamp"
     private val keyShouldSeeWarning = "shouldSeeWarning"
     private val keyShouldSeeWhatsNew = "shouldSeeWhatsNew_v$appVersionName"
+    private val keySstvMode = "sstvMode"
     private val keyUseCustomTle = "useCustomTle"
     private val keyUseCustomTransceivers = "useCustomTransceivers"
     private val keyTleUrl = "tleUrl"
@@ -333,6 +334,7 @@ class SettingsRepo(
                 putBoolean(keyStateOfNightMode, new.stateOfNightMode)
                 putBoolean(keyShouldSeeWarning, new.shouldSeeWarning)
                 putBoolean(keyShouldSeeWhatsNew, new.shouldSeeWhatsNew)
+                putString(keySstvMode, new.sstvMode)
             }
             new
         }
@@ -346,7 +348,8 @@ class SettingsRepo(
         stateOfLightTheme = preferences.getBoolean(keyStateOfLightTheme, false),
         stateOfNightMode = preferences.getBoolean(keyStateOfNightMode, false),
         shouldSeeWarning = preferences.getBoolean(keyShouldSeeWarning, true),
-        shouldSeeWhatsNew = preferences.getBoolean(keyShouldSeeWhatsNew, true)
+        shouldSeeWhatsNew = preferences.getBoolean(keyShouldSeeWhatsNew, true),
+        sstvMode = preferences.getString(keySstvMode, null) ?: "Auto"
     )
     //endregion
 

core/data/src/main/java/com/rtbishop/look4sat/core/data/usecase/AudioCapture.kt

@@ -0,0 +1,63 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.data.usecase
+
+import android.media.AudioFormat
+import android.media.AudioRecord
+import android.media.MediaRecorder
+import androidx.annotation.RequiresPermission
+import com.rtbishop.look4sat.core.domain.usecase.IAudioCapture
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.currentCoroutineContext
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.isActive
+
+class AudioCapture : IAudioCapture {
+
+    override val sampleRate: Int = 44100
+
+    private val channelConfig = AudioFormat.CHANNEL_IN_MONO
+    private val audioFormat = AudioFormat.ENCODING_PCM_FLOAT
+    private val bufferSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat)
+        .coerceAtLeast(sampleRate) // at least 1 second buffer
+
+    @RequiresPermission(android.Manifest.permission.RECORD_AUDIO)
+    override fun audioFlow(): Flow<FloatArray> = flow {
+        val recorder = AudioRecord(
+            MediaRecorder.AudioSource.MIC,
+            sampleRate,
+            channelConfig,
+            audioFormat,
+            bufferSize * 4 // bytes for float
+        )
+        try {
+            recorder.startRecording()
+            val chunkSize = sampleRate / 10 // ~100ms chunks
+            val buffer = FloatArray(chunkSize)
+            while (currentCoroutineContext().isActive) {
+                val read = recorder.read(buffer, 0, chunkSize, AudioRecord.READ_BLOCKING)
+                if (read > 0) emit(if (read == chunkSize) buffer.copyOf() else buffer.copyOfRange(0, read))
+            }
+        } finally {
+            recorder.stop()
+            recorder.release()
+        }
+    }.flowOn(Dispatchers.IO)
+}

core/data/src/main/java/com/rtbishop/look4sat/core/data/usecase/SaveImage.kt

@@ -0,0 +1,84 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.data.usecase
+
+import android.content.ContentValues
+import android.content.Context
+import android.graphics.Bitmap
+import android.os.Build
+import android.os.Environment
+import android.provider.MediaStore
+import com.rtbishop.look4sat.core.domain.usecase.ISaveImage
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import java.io.File
+import java.io.FileOutputStream
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
+
+//Saves images to the device gallery using MediaStore (API 29+) or direct file write (API < 29)
+class SaveImage(private val context: Context) : ISaveImage {
+
+    override suspend fun invoke(pixels: IntArray, width: Int, height: Int, modeName: String): Boolean {
+        return withContext(Dispatchers.IO) {
+            try {
+                val bitmap = Bitmap.createBitmap(pixels, width, height, Bitmap.Config.ARGB_8888)
+                val timestamp = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(Date())
+                val filename = "SSTV_${modeName}_$timestamp.png"
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                    saveWithMediaStore(bitmap, filename)
+                } else {
+                    saveToExternalStorage(bitmap, filename)
+                }
+                bitmap.recycle()
+                true
+            } catch (_: Exception) {
+                false
+            }
+        }
+    }
+
+    private fun saveWithMediaStore(bitmap: Bitmap, filename: String) {
+        val values = ContentValues().apply {
+            put(MediaStore.Images.Media.DISPLAY_NAME, filename)
+            put(MediaStore.Images.Media.MIME_TYPE, "image/png")
+            put(MediaStore.Images.Media.RELATIVE_PATH, "${Environment.DIRECTORY_PICTURES}/Look4Sat")
+            put(MediaStore.Images.Media.IS_PENDING, 1)
+        }
+        val resolver = context.contentResolver
+        val uri = resolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values)
+            ?: throw IllegalStateException("Failed to create MediaStore entry")
+        resolver.openOutputStream(uri)?.use { stream ->
+            bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream)
+        }
+        values.clear()
+        values.put(MediaStore.Images.Media.IS_PENDING, 0)
+        resolver.update(uri, values, null, null)
+    }
+
+    private fun saveToExternalStorage(bitmap: Bitmap, filename: String) {
+        val picturesDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES)
+        val dir = File(picturesDir, "Look4Sat")
+        if (!dir.exists()) dir.mkdirs()
+        val file = File(dir, filename)
+        FileOutputStream(file).use { stream ->
+            bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream)
+        }
+    }
+}

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/model/Settings.kt

@@ -56,7 +56,8 @@ data class OtherSettings(
     val stateOfLightTheme: Boolean,
     val stateOfNightMode: Boolean = false,
     val shouldSeeWarning: Boolean,
-    val shouldSeeWhatsNew: Boolean
+    val shouldSeeWhatsNew: Boolean,
+    val sstvMode: String = "Auto"
 )
 
 data class DataSourcesSettings(

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

@@ -1,6 +1,25 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package com.rtbishop.look4sat.core.domain.repository
 
 import com.rtbishop.look4sat.core.domain.usecase.IAddToCalendar
+import com.rtbishop.look4sat.core.domain.usecase.IAudioCapture
+import com.rtbishop.look4sat.core.domain.usecase.ISaveImage
 import com.rtbishop.look4sat.core.domain.usecase.IShowToast
 import kotlinx.coroutines.CoroutineScope
 
@@ -10,6 +29,7 @@ interface IMainContainer {
     val selectionRepo: ISelectionRepo
     val satelliteRepo: ISatelliteRepo
     val databaseRepo: IDatabaseRepo
+    val radioTrackingService: IRadioTrackingService
     fun provideAddToCalendar(): IAddToCalendar
     fun provideShowToast(): IShowToast
     fun provideBluetoothReporter(): IReporter
@@ -17,7 +37,8 @@ interface IMainContainer {
     fun provideSensorsRepo(): ISensorsRepo
     fun provideTxRadioController(): IRadioController
     fun provideRxRadioController(): IRadioController
-    val radioTrackingService: IRadioTrackingService
+    fun provideAudioCapture(): IAudioCapture
+    fun provideSaveImage(): ISaveImage
 }
 
 interface IContainerProvider {

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/sstv/SstvDecoder.kt

@@ -0,0 +1,573 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.domain.sstv
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.channels.BufferOverflow
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.SharedFlow
+import kotlinx.coroutines.withContext
+import kotlin.math.abs
+import kotlin.math.round
+import kotlin.math.sqrt
+
+class SstvFrame(
+    val imagePixels: IntArray?,
+    val imageWidth: Int,
+    val imageHeight: Int,
+    val modeName: String
+)
+
+class SstvDecoder(
+    sampleRate: Int = 44100,
+    scopeWidth: Int = 320,
+    scopeHeight: Int = 256,
+    private val channelSelect: Int = 0
+) {
+    private val scopeBuffer = PixelBuffer(scopeWidth, scopeHeight * 2)
+    private val imageBuffer = PixelBuffer(scopeWidth, scopeHeight)
+    private val decoder = DecoderEngine(scopeBuffer, imageBuffer, "Raw", sampleRate)
+    private val _frames = MutableSharedFlow<SstvFrame>(
+        replay = 1,
+        onBufferOverflow = BufferOverflow.DROP_OLDEST
+    )
+    val frames: SharedFlow<SstvFrame> = _frames
+    val supportedModes: List<String> = buildList {
+        add("Raw"); add("HF Fax"); decoder.allModes.mapTo(this) { it.name }
+    }
+
+    suspend fun feedSamples(samples: FloatArray) = withContext(Dispatchers.Default) {
+        val hasNewLines = decoder.process(samples, channelSelect)
+        if (hasNewLines) emitFrame()
+    }
+
+    fun lockMode(modeName: String) = decoder.setMode(modeName)
+
+    fun clearPixels() {
+        imageBuffer.line = -1
+        imageBuffer.pixels.fill(0)
+    }
+
+    private fun emitFrame() {
+        val imagePixels = if (imageBuffer.line > 0) imageBuffer.pixels.copyOf() else null
+        val imageWidth = imageBuffer.width
+        val imageHeight = imageBuffer.height
+        val modeName = decoder.currentMode.name
+        _frames.tryEmit(SstvFrame(imagePixels, imageWidth, imageHeight, modeName))
+    }
+}
+
+internal enum class SyncPulseWidth { FiveMs, NineMs, TwentyMs }
+
+internal class SyncPulseDetector(sampleRate: Int) {
+
+    companion object {
+        const val SYNC_FREQ = 1200.0
+        const val BLACK_FREQ = 1500.0
+        const val WHITE_FREQ = 2300.0
+    }
+
+    var detectedWidth: SyncPulseWidth = SyncPulseWidth.NineMs; private set
+    var pulseOffset: Int = 0; private set
+    var freqOffset: Float = 0f; private set
+
+    private val bandwidth = WHITE_FREQ - BLACK_FREQ
+    private val fm = FmDemodulator(bandwidth, sampleRate.toDouble())
+    private val min5ms: Int = round(0.0025 * sampleRate).toInt()
+    private val max5ms: Int = round(0.007 * sampleRate).toInt()
+    private val max9ms: Int = round(0.0145 * sampleRate).toInt()
+    private val max20ms: Int = round(0.025 * sampleRate).toInt()
+    private val filterDelay: Int
+    private val avgFilter: MovingAverage
+    private val delayLine: Delay
+    private val lowPass: ComplexFirFilter
+    private val oscillator: Phasor
+    private val syncFreqValue: Float
+    private val syncFreqTolerance: Float
+    private val trigger: SchmittTrigger
+    private var counter = 0
+    private var baseBand = Complex()
+
+    init {
+        val filterLen = round(0.0025 * sampleRate).toInt() or 1
+        filterDelay = (filterLen - 1) / 2
+        avgFilter = MovingAverage(filterLen)
+        delayLine = Delay(filterLen)
+        val loFreq = 1000.0
+        val hiFreq = 2800.0
+        val cutoff = (hiFreq - loFreq) / 2
+        val lpLen = round(0.002 * sampleRate).toInt() or 1
+        lowPass = ComplexFirFilter(lpLen)
+        for (i in 0 until lpLen)
+            lowPass.taps[i] = (WindowFunctions.kaiser(2.0, i, lpLen) * WindowFunctions.sinc(
+                cutoff,
+                sampleRate.toDouble(),
+                i,
+                lpLen
+            )).toFloat()
+        val center = (loFreq + hiFreq) / 2
+        oscillator = Phasor(-center, sampleRate.toDouble())
+        syncFreqValue = ((SYNC_FREQ - center) * 2 / bandwidth).toFloat()
+        syncFreqTolerance = (50 * 2 / bandwidth).toFloat()
+        val porchFreq = 1500.0
+        val hiThresh = (SYNC_FREQ + porchFreq) / 2
+        val loThresh = (SYNC_FREQ + hiThresh) / 2
+        trigger = SchmittTrigger(
+            ((loThresh - center) * 2 / bandwidth).toFloat(),
+            ((hiThresh - center) * 2 / bandwidth).toFloat()
+        )
+    }
+
+    fun process(buffer: FloatArray, channelSelect: Int): Boolean {
+        var detected = false
+        val channels = if (channelSelect > 0) 2 else 1
+        for (i in 0 until buffer.size / channels) {
+            when (channelSelect) {
+                1 -> baseBand.set(buffer[2 * i])
+                2 -> baseBand.set(buffer[2 * i + 1])
+                3 -> baseBand.set(buffer[2 * i] + buffer[2 * i + 1])
+                4 -> baseBand.set(buffer[2 * i], buffer[2 * i + 1])
+                else -> baseBand.set(buffer[i])
+            }
+            baseBand = lowPass.filter(baseBand.mul(oscillator.rotate()))
+            val freq = fm.demodulate(baseBand)
+            val avg = avgFilter.avg(freq)
+            val delayed = delayLine.push(avg)
+            buffer[i] = freq
+            if (!trigger.process(avg)) {
+                ++counter
+            } else if (counter !in min5ms..max20ms || abs(delayed - syncFreqValue) > syncFreqTolerance) {
+                counter = 0
+            } else {
+                detectedWidth = when {
+                    counter < max5ms -> SyncPulseWidth.FiveMs
+                    counter < max9ms -> SyncPulseWidth.NineMs
+                    else -> SyncPulseWidth.TwentyMs
+                }
+                pulseOffset = i - filterDelay
+                freqOffset = delayed - syncFreqValue
+                detected = true
+                counter = 0
+            }
+        }
+        return detected
+    }
+}
+
+internal class DecoderEngine(
+    private val scopeBuffer: PixelBuffer,
+    private val imageBuffer: PixelBuffer,
+    rawName: String,
+    sampleRate: Int
+) {
+    private val pixelBuffer = PixelBuffer(800, 2)
+    private val detector = SyncPulseDetector(sampleRate)
+    private val pulseFilter: MovingAverage
+    private val pulseFilterDelay: Int
+    private val scanLineBuffer: FloatArray
+    private val scratch: FloatArray
+    private val sync5ms = IntArray(5)
+    private val sync9ms = IntArray(5)
+    private val sync20ms = IntArray(5)
+    private val lines5ms = IntArray(4)
+    private val lines9ms = IntArray(4)
+    private val lines20ms = IntArray(4)
+    private val offsets5ms = FloatArray(5)
+    private val offsets9ms = FloatArray(5)
+    private val offsets20ms = FloatArray(5)
+    private val visFreqs = FloatArray(10)
+    private val scanLineMin: Int
+    private val syncTolerance: Int
+    private val lineTolerance: Int
+    private val leaderLen: Int
+    private val leaderTol: Int
+    private val transition: Int
+    private val visBitLen: Int
+    private val visLen: Int
+    private val rawMode: SstvMode
+    private val hfFaxMode: SstvMode
+    private val modes5ms: ArrayList<SstvMode>
+    private val modes9ms: ArrayList<SstvMode>
+    private val modes20ms: ArrayList<SstvMode>
+
+    var currentMode: SstvMode; private set
+    val allModes: List<SstvMode> get() = modes5ms + modes9ms + modes20ms
+
+    private var lockMode = false
+    private var sample = 0
+    private var leaderBreak = 0
+    private var lastSync = 0
+    private var curLineSamples: Int
+    private var lastOffset = 0f
+
+    init {
+        imageBuffer.line = -1
+        val pfLen = round(0.0025 * sampleRate).toInt() or 1
+        pulseFilterDelay = (pfLen - 1) / 2
+        pulseFilter = MovingAverage(pfLen)
+        scanLineBuffer = FloatArray(round(7.0 * sampleRate).toInt())
+        scratch = FloatArray(round(1.1 * sampleRate).toInt())
+        leaderLen = round(0.3 * sampleRate).toInt()
+        leaderTol = round(0.06 * sampleRate).toInt()
+        transition = round(0.0005 * sampleRate).toInt()
+        visBitLen = round(0.03 * sampleRate).toInt()
+        visLen = round(0.3 * sampleRate).toInt()
+        scanLineMin = round(0.05 * sampleRate).toInt()
+        syncTolerance = round(0.03 * sampleRate).toInt()
+        lineTolerance = round(0.001 * sampleRate).toInt()
+        rawMode = RawMode(rawName, sampleRate)
+        hfFaxMode = HfFaxMode(sampleRate)
+        val robot36 = Robot36Mode(sampleRate)
+        currentMode = robot36
+        curLineSamples = robot36.scanLineSamples
+        modes5ms = arrayListOf(
+            RgbMode.wraaseSc2180(sampleRate),
+            RgbMode.martin("1", 44, 0.146432, sampleRate),
+            RgbMode.martin("2", 40, 0.073216, sampleRate)
+        )
+        modes9ms = arrayListOf(
+            robot36, Robot72Mode(sampleRate),
+            RgbMode.scottie("1", 60, 0.138240, sampleRate),
+            RgbMode.scottie("2", 56, 0.088064, sampleRate),
+            RgbMode.scottie("DX", 76, 0.3456, sampleRate)
+        )
+        modes20ms = arrayListOf(
+            PdMode("50", 93, 320, 256, 0.09152, sampleRate),
+            PdMode("90", 99, 320, 256, 0.17024, sampleRate),
+            PdMode("120", 95, 640, 496, 0.1216, sampleRate),
+            PdMode("160", 98, 512, 400, 0.195584, sampleRate),
+            PdMode("180", 96, 640, 496, 0.18304, sampleRate),
+            PdMode("240", 97, 640, 496, 0.24448, sampleRate),
+            PdMode("290", 94, 800, 616, 0.2288, sampleRate)
+        )
+    }
+
+    fun process(recordBuffer: FloatArray, channelSelect: Int): Boolean {
+        var newLines = false
+        val detected = detector.process(recordBuffer, channelSelect)
+        var syncIdx = sample + detector.pulseOffset
+        val channels = if (channelSelect > 0) 2 else 1
+        for (j in 0 until recordBuffer.size / channels) {
+            if (sample >= scanLineBuffer.size) {
+                shift(curLineSamples)
+                syncIdx -= curLineSamples
+                if (sample >= scanLineBuffer.size) sample = scanLineBuffer.size - 1
+            }
+            scanLineBuffer[sample++] = recordBuffer[j]
+        }
+        if (detected) {
+            when (detector.detectedWidth) {
+                SyncPulseWidth.FiveMs -> newLines = processPulse(modes5ms, offsets5ms, sync5ms, lines5ms, syncIdx)
+                SyncPulseWidth.NineMs -> {
+                    leaderBreak = syncIdx; newLines = processPulse(modes9ms, offsets9ms, sync9ms, lines9ms, syncIdx)
+                }
+
+                SyncPulseWidth.TwentyMs -> {
+                    leaderBreak = syncIdx; newLines = processPulse(modes20ms, offsets20ms, sync20ms, lines20ms, syncIdx)
+                }
+            }
+        } else if (handleHeader()) {
+            newLines = true
+        } else if (sample > lastSync + (curLineSamples * 5) / 4) {
+            copyLines(
+                currentMode.decodeScanLine(
+                    pixelBuffer,
+                    scratch,
+                    scanLineBuffer,
+                    scopeBuffer.width,
+                    lastSync,
+                    curLineSamples,
+                    lastOffset
+                )
+            )
+            lastSync += curLineSamples; newLines = true
+        }
+        return newLines
+    }
+
+    fun setMode(name: String) {
+        if (rawMode.name == name) {
+            lockMode = true; imageBuffer.line = -1; currentMode = rawMode; return
+        }
+        var mode = allModes.firstOrNull { it.name == name }
+        if (mode == null && hfFaxMode.name == name) mode = hfFaxMode
+        if (mode == currentMode) {
+            lockMode = true; return
+        }
+        if (mode != null) {
+            lockMode = true; imageBuffer.line = -1; currentMode = mode; curLineSamples = mode.scanLineSamples; return
+        }
+        lockMode = false
+    }
+
+    private fun mean(a: IntArray): Double = a.sumOf { it.toDouble() } / a.size
+    private fun stdDev(a: IntArray, m: Double): Double {
+        var s = 0.0; for (v in a) s += (v - m) * (v - m); return sqrt(s / a.size)
+    }
+
+    private fun meanF(a: FloatArray): Float {
+        var s = 0f; for (v in a) s += v; return s / a.size
+    }
+
+    private fun detectMode(modes: ArrayList<SstvMode>, samples: Int): SstvMode {
+        var best: SstvMode = rawMode
+        var bestD = Int.MAX_VALUE
+        for (m in modes) {
+            val d = abs(samples - m.scanLineSamples); if (d <= lineTolerance && d < bestD) {
+                bestD = d; best = m
+            }
+        }
+        return best
+    }
+
+    private fun copyUnscaled() {
+        val w = minOf(scopeBuffer.width, pixelBuffer.width)
+        for (row in 0 until pixelBuffer.height) {
+            val line = scopeBuffer.width * scopeBuffer.line
+            pixelBuffer.pixels.copyInto(scopeBuffer.pixels, line, row * pixelBuffer.width, row * pixelBuffer.width + w)
+            scopeBuffer.pixels.fill(0, line + w, line + scopeBuffer.width)
+
+            scopeBuffer.pixels.copyInto(
+                scopeBuffer.pixels,
+                scopeBuffer.width * (scopeBuffer.line + scopeBuffer.height / 2),
+                line,
+                line + scopeBuffer.width
+            )
+            scopeBuffer.line = (scopeBuffer.line + 1) % (scopeBuffer.height / 2)
+        }
+    }
+
+    private fun copyScaled(scale: Int) {
+        for (row in 0 until pixelBuffer.height) {
+            val line = scopeBuffer.width * scopeBuffer.line
+            for (col in 0 until pixelBuffer.width) for (i in 0 until scale) scopeBuffer.pixels[line + col * scale + i] =
+                pixelBuffer.pixels[pixelBuffer.width * row + col]
+            scopeBuffer.pixels.fill(0, line + pixelBuffer.width * scale, line + scopeBuffer.width)
+
+            scopeBuffer.pixels.copyInto(
+                scopeBuffer.pixels,
+                scopeBuffer.width * (scopeBuffer.line + scopeBuffer.height / 2),
+                line,
+                line + scopeBuffer.width
+            )
+            scopeBuffer.line = (scopeBuffer.line + 1) % (scopeBuffer.height / 2)
+            repeat(scale - 1) {
+
+                scopeBuffer.pixels.copyInto(
+                    scopeBuffer.pixels, scopeBuffer.width * scopeBuffer.line, line, line + scopeBuffer.width
+                )
+
+                scopeBuffer.pixels.copyInto(
+                    scopeBuffer.pixels,
+                    scopeBuffer.width * (scopeBuffer.line + scopeBuffer.height / 2),
+                    line,
+                    line + scopeBuffer.width
+                )
+                scopeBuffer.line = (scopeBuffer.line + 1) % (scopeBuffer.height / 2)
+            }
+        }
+    }
+
+    private fun copyLines(ok: Boolean) {
+        if (!ok) return
+        var finish = false
+        if (imageBuffer.line in 0 until imageBuffer.height && imageBuffer.width == pixelBuffer.width) {
+            val w = imageBuffer.width
+            for (row in 0 until pixelBuffer.height) {
+                if (imageBuffer.line >= imageBuffer.height) break
+                pixelBuffer.pixels.copyInto(imageBuffer.pixels, imageBuffer.line * w, row * w, row * w + w)
+                imageBuffer.line++
+            }
+            finish = imageBuffer.line == imageBuffer.height
+        }
+        val scale = scopeBuffer.width / pixelBuffer.width
+        if (scale <= 1) copyUnscaled() else copyScaled(scale)
+        if (finish) drawLines(0xff000000.toInt(), 10)
+    }
+
+    private fun drawLines(color: Int, count: Int) {
+        repeat(count) {
+            scopeBuffer.pixels.fill(
+                color,
+                scopeBuffer.line * scopeBuffer.width,
+                (scopeBuffer.line + 1) * scopeBuffer.width
+            )
+            scopeBuffer.pixels.fill(
+                color,
+                (scopeBuffer.line + scopeBuffer.height / 2) * scopeBuffer.width,
+                (scopeBuffer.line + 1 + scopeBuffer.height / 2) * scopeBuffer.width
+            )
+            scopeBuffer.line = (scopeBuffer.line + 1) % (scopeBuffer.height / 2)
+        }
+    }
+
+    private fun adjust(pulses: IntArray, shift: Int) {
+        for (i in pulses.indices) pulses[i] -= shift
+    }
+
+    private fun shift(amount: Int) {
+        if ((amount <= 0) || (amount > sample)) return
+        sample -= amount; leaderBreak -= amount; lastSync -= amount
+        adjust(sync5ms, amount); adjust(sync9ms, amount); adjust(sync20ms, amount)
+        scanLineBuffer.copyInto(scanLineBuffer, 0, amount, amount + sample)
+    }
+
+    private fun handleHeader(): Boolean {
+        if (leaderBreak < visBitLen + leaderTol || sample < leaderBreak + leaderLen + leaderTol + visLen + visBitLen) return false
+        val bp = leaderBreak; leaderBreak = 0
+        var preFreq = 0f
+        for (i in 0 until leaderTol) preFreq += scanLineBuffer[bp - visBitLen - leaderTol + i]
+        val toneFreq = 1900f
+        val center = 1900f
+        val tol = 50f
+        val halfBw = 400f
+        preFreq = preFreq * halfBw / leaderTol + center
+        if (abs(preFreq - toneFreq) > tol) return false
+        var ldrFreq = 0f
+        for (i in transition until leaderLen - leaderTol) ldrFreq += scanLineBuffer[bp + i]
+        val ldrOffset = ldrFreq / (leaderLen - transition - leaderTol)
+        ldrFreq = ldrOffset * halfBw + center
+        if (abs(ldrFreq - toneFreq) > tol) return false
+        val stopFreq = 1200f
+        val pulseThr = ((stopFreq + toneFreq) / 2 - center) / halfBw
+        var vBegin = bp + leaderLen - leaderTol
+        val vEnd = bp + leaderLen + leaderTol + visBitLen
+        repeat(pulseFilter.length) { pulseFilter.avg(scanLineBuffer[vBegin++] - ldrOffset) }
+        while (++vBegin < vEnd) if (pulseFilter.avg(scanLineBuffer[vBegin] - ldrOffset) < pulseThr) break
+        if (vBegin >= vEnd) return false
+        vBegin -= pulseFilterDelay
+        val visEnd = vBegin + visLen
+        visFreqs.fill(0f)
+        for (j in 0 until 10) for (i in transition until visBitLen - transition) visFreqs[j] += scanLineBuffer[vBegin + visBitLen * j + i] - ldrOffset
+        for (i in 0 until 10) visFreqs[i] = visFreqs[i] * halfBw / (visBitLen - 2 * transition) + center
+        if (abs(visFreqs[0] - stopFreq) > tol || abs(visFreqs[9] - stopFreq) > tol) return false
+        for (i in 1 until 9) if (abs(visFreqs[i] - 1100f) > tol && abs(visFreqs[i] - 1300f) > tol) return false
+        var vis = 0
+        for (i in 0 until 8) vis = vis or ((if (visFreqs[i + 1] < stopFreq) 1 else 0) shl i)
+        var chk = true; for (i in 0 until 8) chk = chk xor ((vis and (1 shl i)) != 0)
+        vis = vis and 127; if (!chk) return false
+        val syncThr = ((1200f + 1500f) / 2 - center) / halfBw
+        var sIdx = visEnd - visBitLen
+        val sMax = visEnd + visBitLen
+        repeat(pulseFilter.length) { pulseFilter.avg(scanLineBuffer[sIdx++] - ldrOffset) }
+        while (++sIdx < sMax) if (pulseFilter.avg(scanLineBuffer[sIdx] - ldrOffset) > syncThr) break
+        if (sIdx >= sMax) return false
+        sIdx -= pulseFilterDelay
+        val mode: SstvMode
+        val pulses: IntArray
+        val lines: IntArray
+        val f5 = modes5ms.firstOrNull { it.visCode == vis }
+        val f9 = modes9ms.firstOrNull { it.visCode == vis }
+        val f20 = modes20ms.firstOrNull { it.visCode == vis }
+        when {
+            f5 != null -> {
+                mode = f5; pulses = sync5ms; lines = lines5ms
+            }
+
+            f9 != null -> {
+                mode = f9; pulses = sync9ms; lines = lines9ms
+            }
+
+            f20 != null -> {
+                mode = f20; pulses = sync20ms; lines = lines20ms
+            }
+
+            else -> {
+                if (!lockMode) drawLines(0xffff0000.toInt(), 8); return false
+            }
+        }
+        if (lockMode && mode != currentMode) return false
+        mode.resetState()
+        imageBuffer.width = mode.width; imageBuffer.height = mode.height
+        imageBuffer.pixels = IntArray(mode.width * mode.height); imageBuffer.line = 0
+        currentMode = mode
+        lastSync = sIdx + mode.firstSyncPulseIndex; curLineSamples = mode.scanLineSamples; lastOffset = ldrOffset
+        var oldest = lastSync - (pulses.size - 1) * curLineSamples
+        if (mode.firstSyncPulseIndex > 0) oldest -= curLineSamples
+        for (i in pulses.indices) pulses[i] = oldest + i * curLineSamples
+        lines.fill(curLineSamples)
+        shift(lastSync + mode.firstPixelSampleIndex)
+        drawLines(0xff00ff00.toInt(), 8); drawLines(0xff000000.toInt(), 10)
+        return true
+    }
+
+    private fun processPulse(
+        modes: ArrayList<SstvMode>,
+        freqOffs: FloatArray,
+        syncPulses: IntArray,
+        lineLen: IntArray,
+        latest: Int
+    ): Boolean {
+        for (i in 1 until syncPulses.size) syncPulses[i - 1] = syncPulses[i]
+        syncPulses[syncPulses.size - 1] = latest
+        for (i in 1 until lineLen.size) lineLen[i - 1] = lineLen[i]
+        lineLen[lineLen.size - 1] = syncPulses.last() - syncPulses[syncPulses.size - 2]
+        for (i in 1 until freqOffs.size) freqOffs[i - 1] = freqOffs[i]
+        freqOffs[freqOffs.size - 1] = detector.freqOffset
+        if (lineLen[0] == 0) return false
+        val m = mean(lineLen)
+        val lineSamples = round(m).toInt()
+        if (lineSamples < scanLineMin || lineSamples > scratch.size) return false
+        if (stdDev(lineLen, m) > lineTolerance) return false
+        var changed = false
+        if (lockMode || imageBuffer.line in 0 until imageBuffer.height) {
+            if (currentMode != rawMode && abs(lineSamples - currentMode.scanLineSamples) > lineTolerance) return false
+        } else {
+            val prev = currentMode; currentMode = detectMode(modes, lineSamples)
+            changed =
+                currentMode != prev || abs(curLineSamples - lineSamples) > lineTolerance || abs(lastSync + lineSamples - syncPulses.last()) > syncTolerance
+        }
+        if (changed) {
+            drawLines(0xff000000.toInt(), 10); drawLines(0xff00ffff.toInt(), 8); drawLines(0xff000000.toInt(), 10)
+        }
+        val offset = meanF(freqOffs)
+        if (syncPulses[0] >= lineSamples && changed) {
+            val end = syncPulses[0]
+            val extra = end / lineSamples
+            val first = end - extra * lineSamples
+            var p = first; while (p < end) {
+                copyLines(
+                    currentMode.decodeScanLine(
+                        pixelBuffer,
+                        scratch,
+                        scanLineBuffer,
+                        scopeBuffer.width,
+                        p,
+                        lineSamples,
+                        offset
+                    )
+                ); p += lineSamples
+            }
+        }
+        val start = if (changed) 0 else lineLen.size - 1
+        for (i in start until lineLen.size) copyLines(
+            currentMode.decodeScanLine(
+                pixelBuffer,
+                scratch,
+                scanLineBuffer,
+                scopeBuffer.width,
+                syncPulses[i],
+                lineLen[i],
+                offset
+            )
+        )
+        lastSync = syncPulses.last(); curLineSamples = lineSamples; lastOffset = offset
+        shift(lastSync + currentMode.firstPixelSampleIndex)
+        return true
+    }
+}

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/sstv/SstvDsp.kt

@@ -0,0 +1,216 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.domain.sstv
+
+import kotlin.math.PI
+import kotlin.math.atan2
+import kotlin.math.cos
+import kotlin.math.pow
+import kotlin.math.round
+import kotlin.math.sin
+import kotlin.math.sqrt
+
+internal class Complex(var real: Float = 0f, var imag: Float = 0f) {
+
+    fun set(real: Float, imag: Float): Complex {
+        this.real = real; this.imag = imag; return this
+    }
+
+    fun set(real: Float): Complex = set(real, 0f)
+
+    fun abs(): Float = sqrt(real * real + imag * imag)
+    fun arg(): Float = atan2(imag, real)
+
+    fun mul(other: Complex): Complex {
+        val tmp = real * other.real - imag * other.imag
+        imag = real * other.imag + imag * other.real
+        real = tmp
+        return this
+    }
+
+    fun div(value: Float): Complex {
+        real /= value; imag /= value; return this
+    }
+}
+
+internal object WindowFunctions {
+
+    fun sinc(cutoff: Double, rate: Double, n: Int, nN: Int): Double {
+        val f = 2 * cutoff / rate
+        val x = n - (nN - 1) / 2.0
+        val fx = f * x
+        return if (fx == 0.0) f else f * sin(PI * fx) / (PI * fx)
+    }
+
+    fun kaiser(a: Double, n: Int, nN: Int): Double {
+        fun square(v: Double) = v * v
+        fun i0(x: Double): Double {
+            val terms = DoubleArray(35)
+            terms[0] = 1.0
+            var v = 1.0
+            for (m in 1 until 35) {
+                v *= x / (2 * m); terms[m] = square(v)
+            }
+            terms.sort()
+            var sum = 0.0; for (m in 34 downTo 0) sum += terms[m]
+            return sum
+        }
+        return i0(PI * a * sqrt(1 - square((2.0 * n) / (nN - 1) - 1))) / i0(PI * a)
+    }
+}
+
+internal open class MovingSum(val length: Int) {
+    private val tree = FloatArray(2 * length)
+    private var leaf = length
+
+    fun add(input: Float) {
+        tree[leaf] = input
+        var child = leaf
+        var parent = leaf / 2
+        while (parent > 0) {
+            tree[parent] = tree[child] + tree[child xor 1]; child = parent; parent /= 2
+        }
+        if (++leaf >= tree.size) leaf = length
+    }
+
+    fun sum(): Float = tree[1]
+    fun sum(input: Float): Float {
+        add(input); return sum()
+    }
+}
+
+internal class MovingAverage(length: Int) : MovingSum(length) {
+    fun avg(input: Float): Float = sum(input) / length
+}
+
+internal class Ema {
+    private var alpha: Float = 1f
+    private var prev: Float = 0f
+
+    fun process(input: Float): Float {
+        prev = prev * (1 - alpha) + alpha * input; return prev
+    }
+
+    fun setCutoff(freq: Double, rate: Double, order: Int = 1) {
+        alpha = computeAlpha(freq, rate, order)
+    }
+
+    fun reset() {
+        prev = 0f
+    }
+
+    companion object {
+
+        fun computeAlpha(freq: Double, rate: Double, order: Int = 1): Float {
+            val x = cos(2 * PI * (freq.coerceAtMost(rate * 0.499)) / rate)
+            val discriminant = (x * (x - 4) + 3).coerceAtLeast(0.0)
+            return (x - 1 + sqrt(discriminant)).coerceIn(0.0, 1.0).pow(1.0 / order).toFloat()
+        }
+
+        fun withCutoff(freq: Double, rate: Double, order: Int = 1): Ema {
+            return Ema().also { it.setCutoff(freq, rate, order) }
+        }
+    }
+}
+
+internal class Phasor(freq: Double, rate: Double) {
+    private val value = Complex(1f, 0f)
+    private val delta: Complex = run {
+        val omega = 2 * PI * freq / rate
+        Complex(cos(omega).toFloat(), sin(omega).toFloat())
+    }
+
+    fun rotate(): Complex = value.div(value.mul(delta).abs())
+}
+
+internal class FmDemodulator(bandwidth: Double, sampleRate: Double) {
+    private val scale = (sampleRate / (bandwidth * PI)).toFloat()
+    private val pi = PI.toFloat()
+    private val twoPi = (2 * PI).toFloat()
+    private var prev = 0f
+
+    fun demodulate(input: Complex): Float {
+        val phase = input.arg()
+        var delta = phase - prev; prev = phase
+        if (delta < -pi) delta += twoPi else if (delta > pi) delta -= twoPi
+        return scale * delta
+    }
+}
+
+internal class ComplexFirFilter(val length: Int) {
+    private val real = FloatArray(length)
+    private val imag = FloatArray(length)
+    private val sum = Complex()
+    private var pos = 0
+
+    val taps = FloatArray(length)
+
+    fun filter(input: Complex): Complex {
+        real[pos] = input.real; imag[pos] = input.imag
+        if (++pos >= length) pos = 0
+        sum.real = 0f; sum.imag = 0f
+        for (tap in taps) {
+            sum.real += tap * real[pos]; sum.imag += tap * imag[pos]; if (++pos >= length) pos = 0
+        }
+        return sum
+    }
+}
+
+internal class Delay(val length: Int) {
+    private val buf = FloatArray(length)
+    private var pos = 0
+
+    fun push(input: Float): Float {
+        val tmp = buf[pos]; buf[pos] = input; if (++pos >= length) pos = 0; return tmp
+    }
+}
+
+internal class SchmittTrigger(private val low: Float, private val high: Float) {
+    private var state = false
+
+    fun process(input: Float): Boolean {
+        if (state) {
+            if (input < low) state = false
+        } else {
+            if (input > high) state = true
+        }
+        return state
+    }
+}
+
+internal object ColorConverter {
+
+    private fun clamp(v: Int) = v.coerceIn(0, 255)
+    private fun toInt(level: Float) = clamp(round(255 * level).toInt())
+    private fun compress(level: Float) = toInt(sqrt(level.coerceIn(0f, 1f)))
+
+    private fun yuv2rgb(yY: Int, uU: Int, vV: Int): Int {
+        val y = yY - 16
+        val u = uU - 128
+        val v = vV - 128
+        val r = clamp((298 * y + 409 * v + 128) shr 8)
+        val g = clamp((298 * y - 100 * u - 208 * v + 128) shr 8)
+        val b = clamp((298 * y + 516 * u + 128) shr 8)
+        return 0xff000000.toInt() or (r shl 16) or (g shl 8) or b
+    }
+
+    fun gray(level: Float): Int = 0xff000000.toInt() or (0x00010101 * compress(level))
+    fun rgb(r: Float, g: Float, b: Float): Int = 0xff000000.toInt() or (toInt(r) shl 16) or (toInt(g) shl 8) or toInt(b)
+    fun yuv2rgb(yY: Float, uU: Float, vV: Float): Int = yuv2rgb(toInt(yY), toInt(uU), toInt(vV))
+    fun yuv2rgb(packed: Int): Int = yuv2rgb((packed shr 16) and 0xff, (packed shr 8) and 0xff, packed and 0xff)
+}

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/sstv/SstvModes.kt

@@ -0,0 +1,474 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.domain.sstv
+
+import kotlin.math.round
+
+internal class PixelBuffer(var width: Int, var height: Int) {
+    var pixels = IntArray(width * height)
+    var line = 0
+}
+
+internal sealed interface SstvMode {
+    val name: String
+    val visCode: Int
+    val width: Int
+    val height: Int
+    val firstPixelSampleIndex: Int
+    val firstSyncPulseIndex: Int
+    val scanLineSamples: Int
+
+    fun resetState() {}
+
+    fun decodeScanLine(
+        pixelBuffer: PixelBuffer,
+        scratch: FloatArray,
+        scanLine: FloatArray,
+        scopeWidth: Int,
+        syncPulseIndex: Int,
+        lineSamples: Int,
+        freqOffset: Float
+    ): Boolean
+}
+
+internal class RgbMode(
+    override val name: String,
+    override val visCode: Int,
+    private val hPixels: Int,
+    private val vPixels: Int,
+    override val firstSyncPulseIndex: Int,
+    override val scanLineSamples: Int,
+    override val firstPixelSampleIndex: Int,
+    private val redBegin: Int,
+    private val redLen: Int,
+    private val greenBegin: Int,
+    private val greenLen: Int,
+    private val blueBegin: Int,
+    private val blueLen: Int,
+    private val endSamples: Int,
+) : SstvMode {
+    override val width get() = hPixels
+    override val height get() = vPixels
+    private val ema = Ema.withCutoff(hPixels.toDouble(), (2 * greenLen).toDouble(), 2)
+
+    override fun decodeScanLine(
+        pixelBuffer: PixelBuffer,
+        scratch: FloatArray,
+        scanLine: FloatArray,
+        scopeWidth: Int,
+        syncPulseIndex: Int,
+        lineSamples: Int,
+        freqOffset: Float
+    ): Boolean {
+        val begin = firstPixelSampleIndex
+        if (syncPulseIndex + begin < 0 || syncPulseIndex + endSamples > scanLine.size) return false
+        ema.reset()
+        for (i in 0 until endSamples - begin) scratch[i] = ema.process(scanLine[syncPulseIndex + begin + i])
+        ema.reset()
+        for (i in endSamples - begin - 1 downTo 0) scratch[i] = freqToLevel(ema.process(scratch[i]), freqOffset)
+        for (i in 0 until hPixels) {
+            val r = redBegin + (i * redLen) / hPixels
+            val g = greenBegin + (i * greenLen) / hPixels
+            val b = blueBegin + (i * blueLen) / hPixels
+            pixelBuffer.pixels[i] = ColorConverter.rgb(scratch[r], scratch[g], scratch[b])
+        }
+        pixelBuffer.width = hPixels; pixelBuffer.height = 1
+        return true
+    }
+
+    companion object {
+        fun martin(variant: String, code: Int, channelSec: Double, sampleRate: Int): RgbMode {
+            val sync = 0.004862
+            val sep = 0.000572
+            val scanLine = sync + sep + 3 * (channelSec + sep)
+            val gEnd = sep + channelSec
+            val bBegin = gEnd + sep
+            val bEnd = bBegin + channelSec
+            val rBegin = bEnd + sep
+            val rEnd = rBegin + channelSec
+            return fromSeconds(
+                name = "Martin $variant",
+                code = code,
+                firstSyncSec = 0.0,
+                scanLineSec = scanLine,
+                beginSec = sep,
+                rBeginSec = rBegin,
+                rEndSec = rEnd,
+                gBeginSec = sep,
+                gEndSec = gEnd,
+                bBeginSec = bBegin,
+                bEndSec = bEnd,
+                endSec = rEnd,
+                sr = sampleRate
+            )
+        }
+
+        fun scottie(variant: String, code: Int, channelSec: Double, sampleRate: Int): RgbMode {
+            val sync = 0.009
+            val sep = 0.0015
+            val firstSync = sync + 2 * (sep + channelSec)
+            val scanLine = sync + 3 * (channelSec + sep)
+            val bEnd = -sync
+            val bBegin = bEnd - channelSec
+            val gEnd = bBegin - sep
+            val gBegin = gEnd - channelSec
+            val rEnd = sep + channelSec
+            return fromSeconds(
+                name = "Scottie $variant",
+                code = code,
+                firstSyncSec = firstSync,
+                scanLineSec = scanLine,
+                beginSec = gBegin,
+                rBeginSec = sep,
+                rEndSec = rEnd,
+                gBeginSec = gBegin,
+                gEndSec = gEnd,
+                bBeginSec = bBegin,
+                bEndSec = bEnd,
+                endSec = rEnd,
+                sr = sampleRate
+            )
+        }
+
+        fun wraaseSc2180(sampleRate: Int): RgbMode {
+            val sync = 0.0055225
+            val porch = 0.0005
+            val ch = 0.235
+            val scanLine = sync + porch + 3 * ch
+            val rEnd = porch + ch
+            val gEnd = rEnd + ch
+            val bEnd = gEnd + ch
+            return fromSeconds(
+                name = "Wraase SC2-180",
+                code = 55,
+                firstSyncSec = 0.0,
+                scanLineSec = scanLine,
+                beginSec = porch,
+                rBeginSec = porch,
+                rEndSec = rEnd,
+                gBeginSec = rEnd,
+                gEndSec = gEnd,
+                bBeginSec = gEnd,
+                bEndSec = bEnd,
+                endSec = bEnd,
+                sr = sampleRate
+            )
+        }
+
+        private fun fromSeconds(
+            name: String, code: Int, w: Int = 320, h: Int = 256,
+            firstSyncSec: Double, scanLineSec: Double, beginSec: Double,
+            rBeginSec: Double, rEndSec: Double, gBeginSec: Double, gEndSec: Double,
+            bBeginSec: Double, bEndSec: Double, endSec: Double, sr: Int
+        ): RgbMode {
+            val begin = round(beginSec * sr).toInt()
+            return RgbMode(
+                name = name, visCode = code, hPixels = w, vPixels = h,
+                firstSyncPulseIndex = round(firstSyncSec * sr).toInt(),
+                scanLineSamples = round(scanLineSec * sr).toInt(),
+                firstPixelSampleIndex = begin,
+                redBegin = round(rBeginSec * sr).toInt() - begin,
+                redLen = round((rEndSec - rBeginSec) * sr).toInt(),
+                greenBegin = round(gBeginSec * sr).toInt() - begin,
+                greenLen = round((gEndSec - gBeginSec) * sr).toInt(),
+                blueBegin = round(bBeginSec * sr).toInt() - begin,
+                blueLen = round((bEndSec - bBeginSec) * sr).toInt(),
+                endSamples = round(endSec * sr).toInt()
+            )
+        }
+    }
+}
+
+internal class Robot36Mode(sampleRate: Int) : SstvMode {
+    override val name = "Robot 36 Color"
+    override val visCode = 8
+    override val width = 320
+    override val height = 240
+    override val firstSyncPulseIndex = 0
+    override val scanLineSamples: Int
+    override val firstPixelSampleIndex: Int
+
+    private val lumSamples: Int
+    private val sepSamples: Int
+    private val chromSamples: Int
+    private val lumBegin: Int
+    private val sepBegin: Int
+    private val chromBegin: Int
+    private val end: Int
+    private val ema: Ema
+    private var lastEven = false
+
+    init {
+        val syncPorch = 0.003
+        val lum = 0.088
+        val sep = 0.0045
+        val porch = 0.0015
+        val chrom = 0.044
+        scanLineSamples = round((0.009 + syncPorch + lum + sep + porch + chrom) * sampleRate).toInt()
+        lumSamples = round(lum * sampleRate).toInt(); sepSamples = round(sep * sampleRate).toInt()
+        chromSamples = round(chrom * sampleRate).toInt()
+        lumBegin = round(syncPorch * sampleRate).toInt(); firstPixelSampleIndex = lumBegin
+        sepBegin = round((syncPorch + lum) * sampleRate).toInt()
+        chromBegin = round((syncPorch + lum + sep + porch) * sampleRate).toInt()
+        end = round((syncPorch + lum + sep + porch + chrom) * sampleRate).toInt()
+        ema = Ema.withCutoff(width.toDouble(), (2 * lumSamples).toDouble(), 2)
+    }
+
+    override fun resetState() {
+        lastEven = false
+    }
+
+    override fun decodeScanLine(
+        pixelBuffer: PixelBuffer,
+        scratch: FloatArray,
+        scanLine: FloatArray,
+        scopeWidth: Int,
+        syncPulseIndex: Int,
+        lineSamples: Int,
+        freqOffset: Float
+    ): Boolean {
+        if (syncPulseIndex + firstPixelSampleIndex < 0 || syncPulseIndex + end > scanLine.size) return false
+        var sep = 0f
+        for (i in 0 until sepSamples) sep += scanLine[syncPulseIndex + sepBegin + i]
+        sep = sep / sepSamples - freqOffset
+        var even = sep < 0
+        if (sep < -1.1f || (sep > -0.9f && sep < 0.9f) || sep > 1.1f) even = !lastEven
+        lastEven = even
+        ema.reset()
+        for (i in firstPixelSampleIndex until end) scratch[i] = ema.process(scanLine[syncPulseIndex + i])
+        ema.reset()
+        for (i in end - 1 downTo firstPixelSampleIndex) scratch[i] = freqToLevel(ema.process(scratch[i]), freqOffset)
+        for (i in 0 until width) {
+            val lPos = lumBegin + (i * lumSamples) / width
+            val cPos = chromBegin + (i * chromSamples) / width
+            if (even) {
+                pixelBuffer.pixels[i] = ColorConverter.rgb(scratch[lPos], 0f, scratch[cPos])
+            } else {
+                val evenYuv = pixelBuffer.pixels[i]
+                val oddYuv = ColorConverter.rgb(scratch[lPos], scratch[cPos], 0f)
+                pixelBuffer.pixels[i] = ColorConverter.yuv2rgb((evenYuv and 0x00ff00ff) or (oddYuv and 0x0000ff00))
+                pixelBuffer.pixels[i + width] =
+                    ColorConverter.yuv2rgb((oddYuv and 0x00ffff00) or (evenYuv and 0x000000ff))
+            }
+        }
+        pixelBuffer.width = width; pixelBuffer.height = 2
+        return !even
+    }
+}
+
+internal class Robot72Mode(sampleRate: Int) : SstvMode {
+    override val name = "Robot 72 Color"
+    override val visCode = 12
+    override val width = 320
+    override val height = 240
+    override val firstSyncPulseIndex = 0
+    override val scanLineSamples: Int
+    override val firstPixelSampleIndex: Int
+
+    private val lumSamples: Int
+    private val chromSamples: Int
+    private val yBegin: Int
+    private val vBegin: Int
+    private val uBegin: Int
+    private val end: Int
+    private val ema: Ema
+
+    init {
+        val syncPorch = 0.003
+        val lum = 0.138
+        val sep = 0.0045
+        val porch = 0.0015
+        val chrom = 0.069
+        scanLineSamples = round((0.009 + syncPorch + lum + 2 * (sep + porch + chrom)) * sampleRate).toInt()
+        lumSamples = round(lum * sampleRate).toInt(); chromSamples = round(chrom * sampleRate).toInt()
+        yBegin = round(syncPorch * sampleRate).toInt(); firstPixelSampleIndex = yBegin
+        vBegin = round((syncPorch + lum + sep + porch) * sampleRate).toInt()
+        uBegin = round((syncPorch + lum + sep + porch + chrom + sep + porch) * sampleRate).toInt()
+        end = round((syncPorch + lum + 2 * (sep + porch + chrom)) * sampleRate).toInt()
+        ema = Ema.withCutoff(width.toDouble(), (2 * lumSamples).toDouble(), 2)
+    }
+
+    override fun decodeScanLine(
+        pixelBuffer: PixelBuffer,
+        scratch: FloatArray,
+        scanLine: FloatArray,
+        scopeWidth: Int,
+        syncPulseIndex: Int,
+        lineSamples: Int,
+        freqOffset: Float
+    ): Boolean {
+        if (syncPulseIndex + firstPixelSampleIndex < 0 || syncPulseIndex + end > scanLine.size) return false
+        ema.reset()
+        for (i in firstPixelSampleIndex until end) scratch[i] = ema.process(scanLine[syncPulseIndex + i])
+        ema.reset()
+        for (i in end - 1 downTo firstPixelSampleIndex) scratch[i] = freqToLevel(ema.process(scratch[i]), freqOffset)
+        for (i in 0 until width) {
+            val yP = yBegin + (i * lumSamples) / width
+            val uP = uBegin + (i * chromSamples) / width
+            val vP = vBegin + (i * chromSamples) / width
+            pixelBuffer.pixels[i] = ColorConverter.yuv2rgb(scratch[yP], scratch[uP], scratch[vP])
+        }
+        pixelBuffer.width = width; pixelBuffer.height = 1
+        return true
+    }
+}
+
+internal class PdMode(
+    variant: String,
+    override val visCode: Int,
+    private val hPixels: Int,
+    private val vPixels: Int,
+    channelSec: Double,
+    sampleRate: Int
+) : SstvMode {
+    override val name = "PD $variant"
+    override val width get() = hPixels
+    override val height get() = vPixels
+    override val firstSyncPulseIndex = 0
+    override val scanLineSamples: Int
+    override val firstPixelSampleIndex: Int
+
+    private val chSamples: Int
+    private val yEvenBegin: Int
+    private val vAvgBegin: Int
+    private val uAvgBegin: Int
+    private val yOddBegin: Int
+    private val end: Int
+    private val ema: Ema
+
+    init {
+        val syncPorch = 0.00208
+        scanLineSamples = round((0.02 + syncPorch + 4 * channelSec) * sampleRate).toInt()
+        chSamples = round(channelSec * sampleRate).toInt()
+        yEvenBegin = round(syncPorch * sampleRate).toInt(); firstPixelSampleIndex = yEvenBegin
+        vAvgBegin = round((syncPorch + channelSec) * sampleRate).toInt()
+        uAvgBegin = round((syncPorch + 2 * channelSec) * sampleRate).toInt()
+        yOddBegin = round((syncPorch + 3 * channelSec) * sampleRate).toInt()
+        end = round((syncPorch + 4 * channelSec) * sampleRate).toInt()
+        ema = Ema.withCutoff(hPixels.toDouble(), (2 * chSamples).toDouble(), 2)
+    }
+
+    override fun decodeScanLine(
+        pixelBuffer: PixelBuffer,
+        scratch: FloatArray,
+        scanLine: FloatArray,
+        scopeWidth: Int,
+        syncPulseIndex: Int,
+        lineSamples: Int,
+        freqOffset: Float
+    ): Boolean {
+        if (syncPulseIndex + firstPixelSampleIndex < 0 || syncPulseIndex + end > scanLine.size) return false
+        ema.reset()
+        for (i in firstPixelSampleIndex until end) scratch[i] = ema.process(scanLine[syncPulseIndex + i])
+        ema.reset()
+        for (i in end - 1 downTo firstPixelSampleIndex) scratch[i] = freqToLevel(ema.process(scratch[i]), freqOffset)
+        for (i in 0 until hPixels) {
+            val pos = (i * chSamples) / hPixels
+            pixelBuffer.pixels[i] =
+                ColorConverter.yuv2rgb(scratch[pos + yEvenBegin], scratch[pos + uAvgBegin], scratch[pos + vAvgBegin])
+            pixelBuffer.pixels[i + hPixels] =
+                ColorConverter.yuv2rgb(scratch[pos + yOddBegin], scratch[pos + uAvgBegin], scratch[pos + vAvgBegin])
+        }
+        pixelBuffer.width = hPixels; pixelBuffer.height = 2
+        return true
+    }
+}
+
+internal class HfFaxMode(private val sampleRate: Int) : SstvMode {
+    override val name = "HF Fax"
+    override val visCode = -1
+    override val width = 640
+    override val height = 1200
+    override val firstPixelSampleIndex = 0
+    override val firstSyncPulseIndex = -1
+    override val scanLineSamples get() = sampleRate / 2
+
+    private val ema = Ema()
+    private val cumulated = FloatArray(width)
+
+    var horizontalShift = 0; private set
+
+    override fun decodeScanLine(
+        pixelBuffer: PixelBuffer,
+        scratch: FloatArray,
+        scanLine: FloatArray,
+        scopeWidth: Int,
+        syncPulseIndex: Int,
+        lineSamples: Int,
+        freqOffset: Float
+    ): Boolean {
+        if (syncPulseIndex < 0 || syncPulseIndex + lineSamples > scanLine.size) return false
+        ema.setCutoff(width.toDouble(), (2 * lineSamples).toDouble(), 2); ema.reset()
+        for (i in 0 until lineSamples) scratch[i] = ema.process(scanLine[syncPulseIndex + i])
+        ema.reset()
+        for (i in lineSamples - 1 downTo 0) scratch[i] = freqToLevel(ema.process(scratch[i]), freqOffset)
+        var bestIdx = 0
+        var bestVal = 0f
+        for (i in 0 until width) {
+            val pos = (i * lineSamples) / width
+            val color = ColorConverter.gray(scratch[pos])
+            pixelBuffer.pixels[i] = color
+            // Grayscale: R==G==B, so luminance is simply the channel value normalized
+            val gray = (color and 0xFF) / 255f
+            cumulated[i] = cumulated[i] * 0.99f + gray * 0.01f
+            if (cumulated[i] > bestVal) {
+                bestIdx = i; bestVal = cumulated[i]
+            }
+        }
+        horizontalShift = bestIdx
+        pixelBuffer.width = width; pixelBuffer.height = 1
+        return true
+    }
+}
+
+internal class RawMode(override val name: String, sampleRate: Int) : SstvMode {
+    override val visCode = -1
+    override val width = -1
+    override val height = -1
+    override val firstPixelSampleIndex = 0
+    override val firstSyncPulseIndex = -1
+    override val scanLineSamples = -1
+
+    private val smallMax = round(0.125 * sampleRate).toInt()
+    private val medMax = round(0.175 * sampleRate).toInt()
+    private val ema = Ema()
+
+    override fun decodeScanLine(
+        pixelBuffer: PixelBuffer,
+        scratch: FloatArray,
+        scanLine: FloatArray,
+        scopeWidth: Int,
+        syncPulseIndex: Int,
+        lineSamples: Int,
+        freqOffset: Float
+    ): Boolean {
+        if (syncPulseIndex < 0 || syncPulseIndex + lineSamples > scanLine.size) return false
+        var px = scopeWidth
+        if (lineSamples < smallMax) px /= 2
+        if (lineSamples < medMax) px /= 2
+        ema.setCutoff(px.toDouble(), (2 * lineSamples).toDouble(), 2); ema.reset()
+        for (i in 0 until lineSamples) scratch[i] = ema.process(scanLine[syncPulseIndex + i])
+        ema.reset()
+        for (i in lineSamples - 1 downTo 0) scratch[i] = freqToLevel(ema.process(scratch[i]), freqOffset)
+        for (i in 0 until px) pixelBuffer.pixels[i] = ColorConverter.gray(scratch[(i * lineSamples) / px])
+        pixelBuffer.width = px; pixelBuffer.height = 1
+        return true
+    }
+}
+
+private fun freqToLevel(frequency: Float, offset: Float): Float = 0.5f * (frequency - offset + 1f)

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/usecase/IAudioCapture.kt

@@ -0,0 +1,34 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.domain.usecase
+
+import kotlinx.coroutines.flow.Flow
+
+/**
+ * Platform abstraction for microphone audio capture.
+ * Produces a flow of mono Float PCM buffers at the configured sample rate.
+ */
+interface IAudioCapture {
+    val sampleRate: Int
+
+    /**
+     * Start capturing audio. Emits FloatArray buffers continuously until the flow is canceled.
+     * Caller is responsible for holding RECORD_AUDIO permission before calling this.
+     */
+    fun audioFlow(): Flow<FloatArray>
+}

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/usecase/ISaveImage.kt

@@ -0,0 +1,26 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.domain.usecase
+
+/**
+ * Saves a decoded SSTV image to the device gallery.
+ * @return true if the image was saved successfully
+ */
+interface ISaveImage {
+    suspend operator fun invoke(pixels: IntArray, width: Int, height: Int, modeName: String): Boolean
+}

core/presentation/src/main/java/com/rtbishop/look4sat/core/presentation/Components.kt

@@ -208,14 +208,11 @@ fun CardButton(onClick: () -> Unit, text: String, modifier: Modifier = Modifier)
 }
 
 @Composable
-fun IconCard(action: () -> Unit, resId: Int, modifier: Modifier = Modifier) {
-    ElevatedCard(modifier = Modifier.size(48.dp)) {
-        Box(
-            modifier = Modifier
-                .clickable(onClick = action)
-                .fillMaxSize(),
-            contentAlignment = Alignment.Center
-        ) { Icon(painter = painterResource(resId), contentDescription = null, modifier = modifier) }
+fun IconCard(action: () -> Unit, resId: Int, modifier: Modifier = Modifier, enabled: Boolean = true) {
+    ElevatedCard(modifier = Modifier.size(48.dp), enabled = enabled, onClick = action) {
+        Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+            Icon(painter = painterResource(resId), contentDescription = null, modifier = modifier)
+        }
     }
 }
 

core/presentation/src/main/res/drawable/ic_delete.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M6,19c0,1.1 0.9,2 2,2h8c1.1,0 2,-0.9 2,-2V7H6v12zM19,4h-3.5l-1,-1h-5l-1,1H5v2h14V4z" />
+</vector>

core/presentation/src/main/res/drawable/ic_pause.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M6,19h4L10,5L6,5v14zM14,5v14h4L18,5h-4z" />
+</vector>

core/presentation/src/main/res/drawable/ic_play.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M8,5v14l11,-7z" />
+</vector>

core/presentation/src/main/res/drawable/ic_save.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M17,3L5,3c-1.11,0 -2,0.9 -2,2v14c0,1.1 0.89,2 2,2h14c1.1,0 2,-0.9 2,-2L21,7l-4,-4zM12,19c-1.66,0 -3,-1.34 -3,-3s1.34,-3 3,-3 3,1.34 3,3 -1.34,3 -3,3zM15,9L5,9L5,5h10v4z" />
+</vector>

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

@@ -17,6 +17,10 @@
  */
 package com.rtbishop.look4sat.feature.radar
 
+import android.Manifest
+import android.content.pm.PackageManager
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.animation.core.LinearEasing
 import androidx.compose.animation.core.RepeatMode
 import androidx.compose.animation.core.animateFloat
@@ -39,6 +43,7 @@ import androidx.compose.material3.PrimaryTabRow
 import androidx.compose.material3.Tab
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Alignment
@@ -49,6 +54,7 @@ import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import androidx.core.content.ContextCompat
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.rtbishop.look4sat.core.domain.predict.OrbitalPos
@@ -76,14 +82,27 @@ fun RadarDestination(navigateUp: () -> Unit) {
     val container = (context.applicationContext as IContainerProvider).getMainContainer()
     val viewModel: RadarViewModel = viewModel(factory = RadarViewModel.factory(container))
     val uiState by viewModel.uiState.collectAsStateWithLifecycle()
-    RadarScreen(uiState, viewModel::onAction, navigateUp)
+    // Sync actual permission state on every recomposition so it survives screen re-entry
+    val hasPermission = ContextCompat.checkSelfPermission(
+        context, Manifest.permission.RECORD_AUDIO
+    ) == PackageManager.PERMISSION_GRANTED
+    LaunchedEffect(hasPermission) {
+        viewModel.onAction(RadarAction.SstvPermissionResult(hasPermission))
+    }
+    val permissionLauncher = rememberLauncherForActivityResult(
+        ActivityResultContracts.RequestPermission()
+    ) { granted -> viewModel.onAction(RadarAction.SstvPermissionResult(granted)) }
+    RadarScreen(uiState, viewModel::onAction, navigateUp, requestMicPermission = {
+        permissionLauncher.launch(Manifest.permission.RECORD_AUDIO)
+    })
 }
 
 @Composable
 private fun RadarScreen(
     uiState: RadarState,
     onAction: (RadarAction) -> Unit,
-    navigateUp: () -> Unit
+    navigateUp: () -> Unit,
+    requestMicPermission: () -> Unit
 ) {
     val upcomingPass = uiState.currentPass ?: getDefaultPass()
     val addToCalendar: () -> Unit = {
@@ -113,11 +132,11 @@ private fun RadarScreen(
         }
         if (isVertical) {
             RadarCard(uiState, Modifier.weight(1f))
-            PagerCard(uiState, onAction, Modifier.weight(1f))
+            PagerCard(uiState, onAction, requestMicPermission, Modifier.weight(1f))
         } else {
             Row(horizontalArrangement = Arrangement.spacedBy(6.dp)) {
                 RadarCard(uiState, Modifier.weight(1f))
-                PagerCard(uiState, onAction, Modifier.weight(1f))
+                PagerCard(uiState, onAction, requestMicPermission, Modifier.weight(1f))
             }
         }
     }
@@ -127,6 +146,7 @@ private fun RadarScreen(
 private fun PagerCard(
     uiState: RadarState,
     onAction: (RadarAction) -> Unit,
+    requestMicPermission: () -> Unit,
     modifier: Modifier = Modifier
 ) {
     val pages = RadarPage.entries
@@ -155,38 +175,17 @@ private fun PagerCard(
                         radioControl = uiState.radioControl,
                         onAction = onAction
                     )
-                    RadarPage.Sstv -> SstvPlaceholderPage()
+                    RadarPage.Sstv -> SstvPage(
+                        sstv = uiState.sstv,
+                        onAction = onAction,
+                        requestMicPermission = requestMicPermission
+                    )
                 }
             }
         }
     }
 }
 
-@Composable
-private fun SstvPlaceholderPage() {
-    Box(
-        contentAlignment = Alignment.Center,
-        modifier = Modifier.fillMaxSize()
-    ) {
-        Column(
-            horizontalAlignment = Alignment.CenterHorizontally,
-            verticalArrangement = Arrangement.spacedBy(12.dp)
-        ) {
-            Text(text = "🚧", fontSize = 48.sp)
-            Text(
-                text = "SSTV Decoder",
-                fontSize = 20.sp,
-                color = MaterialTheme.colorScheme.primary
-            )
-            Text(
-                text = "Coming soon",
-                fontSize = 16.sp,
-                color = MaterialTheme.colorScheme.onSurfaceVariant
-            )
-        }
-    }
-}
-
 @Composable
 private fun RadarCard(uiState: RadarState, modifier: Modifier = Modifier) {
     val satellitePos = uiState.orbitalPos

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

@@ -21,6 +21,7 @@ import com.rtbishop.look4sat.core.domain.model.SatRadio
 import com.rtbishop.look4sat.core.domain.predict.CelestialComputer
 import com.rtbishop.look4sat.core.domain.predict.OrbitalPass
 import com.rtbishop.look4sat.core.domain.predict.OrbitalPos
+import com.rtbishop.look4sat.core.domain.sstv.SstvFrame
 
 data class RadioPanelState(
     val label: String = "",
@@ -57,7 +58,18 @@ data class RadarState(
     val transmitters: List<SatRadio> = emptyList(),
     val selectedTransmitterUuid: String? = null,
     val selectedFrequency: Long? = null,
-    val radioControl: RadioControlSubState = RadioControlSubState()
+    val radioControl: RadioControlSubState = RadioControlSubState(),
+    val sstv: SstvSubState = SstvSubState()
+)
+
+enum class SstvStatus { Idle, Recording, Saving }
+
+data class SstvSubState(
+    val status: SstvStatus = SstvStatus.Idle,
+    val hasPermission: Boolean = false,
+    val selectedMode: String = "Auto",
+    val supportedModes: List<String> = emptyList(),
+    val currentFrame: SstvFrame? = null
 )
 
 sealed interface RadarAction {
@@ -72,4 +84,12 @@ sealed interface RadarAction {
     data object ToggleTracking : RadarAction
     data object ConnectRadios : RadarAction
     data object DisconnectRadios : RadarAction
+
+    // SSTV actions
+    data object SstvStartRecording : RadarAction
+    data object SstvStopRecording : RadarAction
+    data object SstvSaveImage : RadarAction
+    data object SstvReset : RadarAction
+    data class SstvSelectMode(val modeName: String) : RadarAction
+    data class SstvPermissionResult(val granted: Boolean) : RadarAction
 }

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

@@ -38,6 +38,7 @@ import androidx.compose.ui.graphics.Path
 import androidx.compose.ui.graphics.PathEffect
 import androidx.compose.ui.graphics.PathMeasure
 import androidx.compose.ui.graphics.ShaderBrush
+import androidx.compose.ui.graphics.ColorFilter
 import androidx.compose.ui.graphics.StampedPathEffectStyle
 import androidx.compose.ui.graphics.SweepGradientShader
 import androidx.compose.ui.graphics.drawscope.DrawScope
@@ -220,7 +221,7 @@ private fun DrawScope.drawBodyIcon(
         translate(pos.x - half, pos.y - half)
     }) {
         with(painter) {
-            draw(Size(iconSize, iconSize), colorFilter = androidx.compose.ui.graphics.ColorFilter.tint(color))
+            draw(Size(iconSize, iconSize), colorFilter = ColorFilter.tint(color))
         }
     }
 }

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

@@ -24,6 +24,7 @@ import androidx.lifecycle.viewmodel.viewModelFactory
 import com.rtbishop.look4sat.core.domain.model.SatRadio
 import com.rtbishop.look4sat.core.domain.predict.CelestialComputer
 import com.rtbishop.look4sat.core.domain.predict.OrbitalObject
+import com.rtbishop.look4sat.core.domain.predict.OrbitalPass
 import com.rtbishop.look4sat.core.domain.predict.OrbitalPos
 import com.rtbishop.look4sat.core.domain.repository.IMainContainer
 import com.rtbishop.look4sat.core.domain.repository.IRadioTrackingService
@@ -31,10 +32,15 @@ import com.rtbishop.look4sat.core.domain.repository.IReporter
 import com.rtbishop.look4sat.core.domain.repository.ISatelliteRepo
 import com.rtbishop.look4sat.core.domain.repository.ISensorsRepo
 import com.rtbishop.look4sat.core.domain.repository.ISettingsRepo
+import com.rtbishop.look4sat.core.domain.sstv.SstvDecoder
+import com.rtbishop.look4sat.core.domain.usecase.IAudioCapture
 import com.rtbishop.look4sat.core.domain.usecase.IAddToCalendar
+import com.rtbishop.look4sat.core.domain.usecase.ISaveImage
+import com.rtbishop.look4sat.core.domain.usecase.IShowToast
 import com.rtbishop.look4sat.core.domain.utility.round
 import com.rtbishop.look4sat.core.domain.utility.toDegrees
 import com.rtbishop.look4sat.core.domain.utility.toTimerString
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -51,91 +57,100 @@ class RadarViewModel(
     private val settingsRepo: ISettingsRepo,
     private val sensorsRepo: ISensorsRepo,
     private val addToCalendar: IAddToCalendar,
-    private val trackingService: IRadioTrackingService
+    private val trackingService: IRadioTrackingService,
+    private val audioCapture: IAudioCapture,
+    private val saveImage: ISaveImage,
+    private val showToast: IShowToast
 ) : ViewModel() {
 
     private val stationPos = settingsRepo.stationPosition.value
     private val magDeclination = sensorsRepo.getMagDeclination(stationPos)
     private var transponders: List<SatRadio> = emptyList()
+    private var sstvDecoder: SstvDecoder? = null
+    private var sstvRecordingJob: Job? = null
 
     private val _uiState = MutableStateFlow(
         RadarState(
             isUtc = settingsRepo.otherSettings.value.stateOfUtc,
             orientationValues = sensorsRepo.orientation.value,
             shouldShowSweep = settingsRepo.otherSettings.value.stateOfSweep,
-            shouldUseCompass = settingsRepo.otherSettings.value.stateOfSensors
+            shouldUseCompass = settingsRepo.otherSettings.value.stateOfSensors,
+            sstv = SstvSubState(selectedMode = settingsRepo.otherSettings.value.sstvMode)
         )
     )
     val uiState: StateFlow<RadarState> = _uiState
 
     init {
-        // Compass sensor collection
-        if (settingsRepo.otherSettings.value.stateOfSensors) {
-            viewModelScope.launch {
-                sensorsRepo.enableSensor()
-                sensorsRepo.orientation.collect { data ->
-                    val orientationValues = (data.first + magDeclination) to data.second
-                    _uiState.update { it.copy(orientationValues = orientationValues) }
-                }
+        collectCompassSensor()
+        collectSettingsChanges()
+        collectPassAndStartTickLoop()
+        collectRadioTrackingState()
+    }
+
+    private fun collectCompassSensor() {
+        if (!settingsRepo.otherSettings.value.stateOfSensors) return
+        viewModelScope.launch {
+            sensorsRepo.enableSensor()
+            sensorsRepo.orientation.collect { data ->
+                val orientationValues = (data.first + magDeclination) to data.second
+                _uiState.update { it.copy(orientationValues = orientationValues) }
             }
         }
-        // React to UTC setting changes
+    }
+
+    private fun collectSettingsChanges() {
         viewModelScope.launch {
             settingsRepo.otherSettings.collectLatest { settings ->
                 _uiState.update { it.copy(isUtc = settings.stateOfUtc) }
             }
         }
-        // Resolve which pass we're tracking and start the tick loop
+    }
+
+    private fun collectPassAndStartTickLoop() {
         viewModelScope.launch {
             val passes = satelliteRepo.passes.value
             val (catNum, aosTime) = satelliteRepo.selectedPass.value
-            val satPass = passes.find { it.catNum == catNum && it.aosTime == aosTime } ?: passes.firstOrNull()
-            satPass?.let { pass ->
-                _uiState.update { it.copy(currentPass = pass) }
-                val transmittersList = satelliteRepo.getRadiosWithId(pass.catNum)
-                // Load transponders for radio control (ones that have downlink)
-                transponders = transmittersList.filter { it.downlinkLow != null }
-                _uiState.update { state ->
-                    state.copy(radioControl = state.radioControl.copy(transponders = transponders))
-                }
-                // Auto-expand the first item so users discover the expandable UI
-                if (transmittersList.isNotEmpty()) {
-                    val firstUuid = transmittersList.first().uuid
-                    _uiState.update { it.copy(selectedTransmitterUuid = firstUuid) }
-                    transponders.find { it.uuid == firstUuid }?.let {
-                        trackingService.setTransponder(it)
-                    }
-                }
-                // Compute track once (it doesn't change for a given pass)
-                if (!pass.isDeepSpace) {
-                    val track = satelliteRepo.getTrack(pass.orbitalObject, stationPos, pass.aosTime, pass.losTime)
-                    _uiState.update { it.copy(satTrack = track) }
-                }
-                // Tick loop — position, timer, and radio updates every second
-                while (isActive) {
-                    val timeNow = System.currentTimeMillis()
-                    val pos = satelliteRepo.getPosition(pass.orbitalObject, stationPos, timeNow)
-                    val sunPos = CelestialComputer.getSunPosition(stationPos, timeNow)
-                    val moonPos = CelestialComputer.getMoonPosition(stationPos, timeNow)
-                    val (time, isAos) = computeTimer(pass.isDeepSpace, pass.aosTime, pass.losTime, timeNow)
-                    val isLos = !pass.isDeepSpace && timeNow > pass.losTime
-                    _uiState.update {
-                        it.copy(
-                            currentTime = time,
-                            isTimeAos = isAos,
-                            isLos = isLos,
-                            orbitalPos = pos,
-                            sunPosition = sunPos,
-                            moonPosition = moonPos
-                        )
-                    }
-                    processRadios(transmittersList, pass.orbitalObject, timeNow)
-                    sendPassData(pos)
-                    delay(1000)
-                }
+            val pass = passes.find { it.catNum == catNum && it.aosTime == aosTime } ?: passes.firstOrNull() ?: return@launch
+            _uiState.update { it.copy(currentPass = pass) }
+            val transmittersList = satelliteRepo.getRadiosWithId(pass.catNum)
+            transponders = transmittersList.filter { it.downlinkLow != null }
+            _uiState.update { state ->
+                state.copy(radioControl = state.radioControl.copy(transponders = transponders))
+            }
+            if (transmittersList.isNotEmpty()) {
+                val firstUuid = transmittersList.first().uuid
+                _uiState.update { it.copy(selectedTransmitterUuid = firstUuid) }
+                transponders.find { it.uuid == firstUuid }?.let { trackingService.setTransponder(it) }
+            }
+            if (!pass.isDeepSpace) {
+                val track = satelliteRepo.getTrack(pass.orbitalObject, stationPos, pass.aosTime, pass.losTime)
+                _uiState.update { it.copy(satTrack = track) }
+            }
+            while (isActive) {
+                tickPass(pass, transmittersList)
+                delay(1000)
             }
         }
-        // Observe radio tracking service state
+    }
+
+    private suspend fun tickPass(pass: OrbitalPass, transmittersList: List<SatRadio>) {
+        val timeNow = System.currentTimeMillis()
+        val pos = satelliteRepo.getPosition(pass.orbitalObject, stationPos, timeNow)
+        val sunPos = CelestialComputer.getSunPosition(stationPos, timeNow)
+        val moonPos = CelestialComputer.getMoonPosition(stationPos, timeNow)
+        val (time, isAos) = computeTimer(pass.isDeepSpace, pass.aosTime, pass.losTime, timeNow)
+        val isLos = !pass.isDeepSpace && timeNow > pass.losTime
+        _uiState.update {
+            it.copy(
+                currentTime = time, isTimeAos = isAos, isLos = isLos,
+                orbitalPos = pos, sunPosition = sunPos, moonPosition = moonPos
+            )
+        }
+        processRadios(transmittersList, pass.orbitalObject, timeNow)
+        sendPassData(pos)
+    }
+
+    private fun collectRadioTrackingState() {
         viewModelScope.launch {
             trackingService.state.collect { svc ->
                 _uiState.update { state ->
@@ -210,6 +225,33 @@ class RadarViewModel(
             }
             RadarAction.ConnectRadios -> viewModelScope.launch { trackingService.connectRadios() }
             RadarAction.DisconnectRadios -> viewModelScope.launch { trackingService.disconnectRadios() }
+
+            // SSTV actions
+            is RadarAction.SstvPermissionResult -> {
+                _uiState.update { it.copy(sstv = it.sstv.copy(hasPermission = action.granted)) }
+                if (action.granted) initSstvDecoder()
+            }
+            RadarAction.SstvStartRecording -> startSstvRecording()
+            RadarAction.SstvStopRecording -> stopSstvRecording()
+            RadarAction.SstvSaveImage -> {
+                val frame = _uiState.value.sstv.currentFrame ?: return
+                val pixels = frame.imagePixels ?: return
+                _uiState.update { it.copy(sstv = it.sstv.copy(status = SstvStatus.Saving)) }
+                viewModelScope.launch {
+                    saveImage(pixels, frame.imageWidth, frame.imageHeight, frame.modeName)
+                    _uiState.update { it.copy(sstv = it.sstv.copy(status = SstvStatus.Idle)) }
+                    showToast("Image saved")
+                }
+            }
+            is RadarAction.SstvSelectMode -> {
+                sstvDecoder?.lockMode(action.modeName)
+                _uiState.update { it.copy(sstv = it.sstv.copy(selectedMode = action.modeName)) }
+                settingsRepo.updateOtherSettings { it.copy(sstvMode = action.modeName) }
+            }
+            RadarAction.SstvReset -> {
+                sstvDecoder?.clearPixels() // Keep decoder alive, just reset pixels
+                _uiState.update { it.copy(sstv = it.sstv.copy(currentFrame = null)) }
+            }
         }
     }
 
@@ -281,6 +323,36 @@ class RadarViewModel(
         }
     }
 
+    private fun initSstvDecoder() {
+        if (sstvDecoder == null) {
+            val decoder = SstvDecoder(sampleRate = audioCapture.sampleRate)
+            sstvDecoder = decoder
+            _uiState.update { it.copy(sstv = it.sstv.copy(supportedModes = decoder.supportedModes)) }
+            viewModelScope.launch {
+                decoder.frames.collect { frame ->
+                    _uiState.update { it.copy(sstv = it.sstv.copy(currentFrame = frame)) }
+                }
+            }
+        }
+    }
+
+    private fun startSstvRecording() {
+        if (sstvRecordingJob?.isActive == true) return
+        initSstvDecoder()
+        _uiState.update { it.copy(sstv = it.sstv.copy(status = SstvStatus.Recording)) }
+        sstvRecordingJob = viewModelScope.launch {
+            audioCapture.audioFlow().collect { buffer ->
+                sstvDecoder?.feedSamples(buffer)
+            }
+        }
+    }
+
+    private fun stopSstvRecording() {
+        sstvRecordingJob?.cancel()
+        sstvRecordingJob = null
+        _uiState.update { it.copy(sstv = it.sstv.copy(status = SstvStatus.Idle)) }
+    }
+
     companion object {
 
         val CTCSS_TONES = listOf(
@@ -307,7 +379,10 @@ class RadarViewModel(
                     settingsRepo = container.settingsRepo,
                     sensorsRepo = container.provideSensorsRepo(),
                     addToCalendar = container.provideAddToCalendar(),
-                    trackingService = container.radioTrackingService
+                    trackingService = container.radioTrackingService,
+                    audioCapture = container.provideAudioCapture(),
+                    saveImage = container.provideSaveImage(),
+                    showToast = container.provideShowToast()
                 )
             }
         }

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

@@ -1,369 +0,0 @@
-/*
- * Look4Sat. Amateur radio satellite tracker and pass predictor.
- * Copyright (C) 2019-2026 Arty Bishop and contributors.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-package com.rtbishop.look4sat.feature.radar
-
-import androidx.compose.foundation.background
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Box
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.ExperimentalLayoutApi
-import androidx.compose.foundation.layout.FlowRow
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.size
-import androidx.compose.foundation.layout.width
-import androidx.compose.foundation.shape.CircleShape
-import androidx.compose.material3.DropdownMenuItem
-import androidx.compose.material3.ElevatedCard
-import androidx.compose.material3.ExperimentalMaterial3Api
-import androidx.compose.material3.ExposedDropdownMenuBox
-import androidx.compose.material3.ExposedDropdownMenuDefaults
-import androidx.compose.material3.FilterChip
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.ExposedDropdownMenuAnchorType
-import androidx.compose.material3.OutlinedTextField
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
-import androidx.compose.ui.Alignment
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.draw.clip
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.text.font.FontWeight
-import androidx.compose.ui.text.style.TextOverflow
-import androidx.compose.ui.unit.dp
-import androidx.compose.ui.unit.sp
-import com.rtbishop.look4sat.core.domain.model.SatRadio
-import com.rtbishop.look4sat.core.presentation.CardButton
-import java.util.Locale
-
-@Composable
-fun RadioControlPage(
-    radioState: RadioControlSubState,
-    onAction: (RadarAction) -> Unit,
-    modifier: Modifier = Modifier
-) {
-    val selectedTransponder = radioState.transponders.find {
-        it.uuid == radioState.selectedTransponderUuid
-    }
-
-    Column(
-        modifier = modifier
-            .fillMaxSize()
-            .padding(horizontal = 6.dp, vertical = 6.dp),
-        verticalArrangement = Arrangement.spacedBy(6.dp)
-    ) {
-        // Transponder selector (dropdown)
-        TransponderDropdown(
-            transponders = radioState.transponders,
-            selectedTransponder = selectedTransponder,
-            onAction = onAction
-        )
-
-        // Active transponder status (TX/RX lines)
-        if (selectedTransponder != null) {
-            ActiveTransponderStatus(
-                transponder = selectedTransponder,
-                txPanel = radioState.txPanel,
-                rxPanel = radioState.rxPanel
-            )
-        }
-
-        // Frequency tuner + CTCSS
-        if (radioState.txBaseFrequencyHz != null) {
-            FrequencyTunerCard(
-                txBaseFrequencyHz = radioState.txBaseFrequencyHz,
-                selectedTransponder = selectedTransponder,
-                ctcssTone = radioState.ctcssTone,
-                showCtcss = selectedTransponder?.uplinkMode?.uppercase() == "FM",
-                onAction = onAction
-            )
-        }
-
-        Spacer(modifier = Modifier.weight(1f))
-
-        // Error message
-        radioState.errorMessage?.let { msg ->
-            Text(
-                text = msg,
-                color = MaterialTheme.colorScheme.error,
-                fontSize = 13.sp,
-                modifier = Modifier.padding(horizontal = 4.dp)
-            )
-        }
-
-        // Control buttons
-        ControlButtons(
-            isConnected = radioState.txPanel.isConnected || radioState.rxPanel.isConnected,
-            isTracking = radioState.isTracking,
-            onAction = onAction
-        )
-    }
-}
-
-@OptIn(ExperimentalMaterial3Api::class)
-@Composable
-private fun TransponderDropdown(
-    transponders: List<SatRadio>,
-    selectedTransponder: SatRadio?,
-    onAction: (RadarAction) -> Unit
-) {
-    var expanded by remember { mutableStateOf(false) }
-
-    ExposedDropdownMenuBox(
-        expanded = expanded,
-        onExpandedChange = { expanded = it }
-    ) {
-        OutlinedTextField(
-            value = selectedTransponder?.info ?: "No transponders available",
-            onValueChange = {},
-            readOnly = true,
-            singleLine = true,
-            textStyle = MaterialTheme.typography.bodyMedium,
-            trailingIcon = { ExposedDropdownMenuDefaults.TrailingIcon(expanded = expanded) },
-            modifier = Modifier
-                .fillMaxWidth()
-                .menuAnchor(ExposedDropdownMenuAnchorType.PrimaryNotEditable)
-        )
-        ExposedDropdownMenu(
-            expanded = expanded,
-            onDismissRequest = { expanded = false }
-        ) {
-            transponders.forEach { radio ->
-                val invLabel = if (radio.isInverted) " INV" else ""
-                val modeLabel = "${radio.uplinkMode ?: "--"}/${radio.downlinkMode ?: "--"}$invLabel"
-                DropdownMenuItem(
-                    text = {
-                        Row(
-                            horizontalArrangement = Arrangement.SpaceBetween,
-                            modifier = Modifier.fillMaxWidth()
-                        ) {
-                            Text(
-                                text = radio.info,
-                                maxLines = 1,
-                                overflow = TextOverflow.Ellipsis,
-                                modifier = Modifier.weight(1f)
-                            )
-                            Spacer(modifier = Modifier.width(8.dp))
-                            Text(
-                                text = modeLabel,
-                                fontSize = 13.sp,
-                                color = MaterialTheme.colorScheme.onSurfaceVariant
-                            )
-                        }
-                    },
-                    onClick = {
-                        onAction(RadarAction.SelectTransponder(radio.uuid))
-                        expanded = false
-                    }
-                )
-            }
-        }
-    }
-}
-
-@Composable
-private fun ActiveTransponderStatus(
-    transponder: SatRadio,
-    txPanel: RadioPanelState,
-    rxPanel: RadioPanelState
-) {
-    ElevatedCard(modifier = Modifier.fillMaxWidth()) {
-        Column(
-            modifier = Modifier.padding(horizontal = 12.dp, vertical = 8.dp),
-            verticalArrangement = Arrangement.spacedBy(4.dp)
-        ) {
-            // TX line (uplink — on top)
-            FrequencyStatusRow(
-                label = "TX",
-                frequency = txPanel.frequencyHz ?: transponder.uplinkLow,
-                isConnected = txPanel.isConnected,
-                mode = txPanel.mode
-            )
-            // RX line (downlink — below)
-            FrequencyStatusRow(
-                label = "RX",
-                frequency = rxPanel.frequencyHz ?: transponder.downlinkLow,
-                isConnected = rxPanel.isConnected,
-                mode = rxPanel.mode
-            )
-        }
-    }
-}
-
-@Composable
-private fun FrequencyStatusRow(
-    label: String,
-    frequency: Long?,
-    isConnected: Boolean,
-    mode: String?
-) {
-    Row(
-        verticalAlignment = Alignment.CenterVertically,
-        modifier = Modifier.fillMaxWidth()
-    ) {
-        Text(
-            text = "$label:",
-            fontSize = 13.sp,
-            color = MaterialTheme.colorScheme.onSurfaceVariant,
-            modifier = Modifier.width(28.dp)
-        )
-        Text(
-            text = frequency?.let { RadarViewModel.formatFrequency(it) } ?: "—",
-            fontSize = 18.sp,
-            fontWeight = FontWeight.Bold,
-            color = MaterialTheme.colorScheme.primary,
-            modifier = Modifier.weight(1f)
-        )
-        if (mode != null) {
-            Text(
-                text = mode,
-                fontSize = 12.sp,
-                color = MaterialTheme.colorScheme.onSurfaceVariant,
-                modifier = Modifier.padding(end = 6.dp)
-            )
-        }
-        Box(
-            modifier = Modifier
-                .size(8.dp)
-                .clip(CircleShape)
-                .background(if (isConnected) Color(0xFF4CAF50) else Color(0xFFE57373))
-        )
-    }
-}
-
-@OptIn(ExperimentalLayoutApi::class)
-@Composable
-private fun FrequencyTunerCard(
-    txBaseFrequencyHz: Long,
-    selectedTransponder: SatRadio?,
-    ctcssTone: Double?,
-    showCtcss: Boolean,
-    onAction: (RadarAction) -> Unit
-) {
-    ElevatedCard(modifier = Modifier.fillMaxWidth()) {
-        Column(
-            horizontalAlignment = Alignment.CenterHorizontally,
-            modifier = Modifier.padding(horizontal = 8.dp, vertical = 6.dp)
-        ) {
-            // TX Base Frequency label + value on one line
-            Row(
-                verticalAlignment = Alignment.CenterVertically,
-                horizontalArrangement = Arrangement.Center,
-                modifier = Modifier.fillMaxWidth()
-            ) {
-                Text(
-                    text = "TX Base: ",
-                    fontSize = 14.sp,
-                    color = MaterialTheme.colorScheme.onSurfaceVariant
-                )
-                Text(
-                    text = "${RadarViewModel.formatFrequency(txBaseFrequencyHz)} MHz",
-                    fontSize = 18.sp,
-                    fontWeight = FontWeight.Bold,
-                    color = MaterialTheme.colorScheme.primary
-                )
-            }
-            // Show band range hint if it's a wide transponder
-            if (selectedTransponder != null) {
-                val upLow = selectedTransponder.uplinkLow
-                val upHigh = selectedTransponder.uplinkHigh
-                if (upLow != null && upHigh != null && upLow != upHigh) {
-                    Text(
-                        text = "(${RadarViewModel.formatFrequency(upLow)} – ${RadarViewModel.formatFrequency(upHigh)})",
-                        fontSize = 11.sp,
-                        color = MaterialTheme.colorScheme.onSurfaceVariant
-                    )
-                }
-            }
-            Spacer(modifier = Modifier.height(4.dp))
-            // Adjustment buttons
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                FREQ_ADJUSTMENTS.forEach { (delta, label) ->
-                    CardButton(
-                        onClick = { onAction(RadarAction.AdjustTxFrequency(delta)) },
-                        text = label,
-                        modifier = Modifier.weight(1f)
-                    )
-                }
-            }
-            // CTCSS inline (only for FM)
-            if (showCtcss) {
-                Spacer(modifier = Modifier.height(6.dp))
-                Text(
-                    text = "CTCSS",
-                    fontSize = 12.sp,
-                    color = MaterialTheme.colorScheme.onSurfaceVariant
-                )
-                FlowRow(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                    FilterChip(
-                        selected = ctcssTone == null,
-                        onClick = { onAction(RadarAction.SetCtcssTone(null)) },
-                        label = { Text("Off", fontSize = 12.sp) }
-                    )
-                    RadarViewModel.CTCSS_TONES.forEach { tone ->
-                        FilterChip(
-                            selected = ctcssTone == tone,
-                            onClick = { onAction(RadarAction.SetCtcssTone(tone)) },
-                            label = { Text(String.format(Locale.ENGLISH, "%.1f", tone), fontSize = 12.sp) }
-                        )
-                    }
-                }
-            }
-        }
-    }
-}
-
-
-@Composable
-private fun ControlButtons(
-    isConnected: Boolean,
-    isTracking: Boolean,
-    onAction: (RadarAction) -> Unit
-) {
-    Row(horizontalArrangement = Arrangement.spacedBy(6.dp)) {
-        if (!isConnected) {
-            CardButton(
-                onClick = { onAction(RadarAction.ConnectRadios) },
-                text = "Connect",
-                modifier = Modifier.weight(1f)
-            )
-        } else {
-            CardButton(
-                onClick = { onAction(RadarAction.DisconnectRadios) },
-                text = "Disconnect",
-                modifier = Modifier.weight(1f)
-            )
-        }
-        CardButton(
-            onClick = { onAction(RadarAction.ToggleTracking) },
-            text = if (isTracking) "Stop" else "Track",
-            modifier = Modifier.weight(1f)
-        )
-    }
-}
-
-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")

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

@@ -0,0 +1,240 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.feature.radar
+
+import android.graphics.Bitmap
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.background
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material3.Button
+import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.ElevatedCard
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.RadioButton
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.asImageBitmap
+import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.compose.ui.window.Dialog
+import com.rtbishop.look4sat.core.presentation.IconCard
+import com.rtbishop.look4sat.core.presentation.R
+import com.rtbishop.look4sat.core.presentation.infiniteMarquee
+
+@Composable
+internal fun SstvPage(
+    sstv: SstvSubState,
+    onAction: (RadarAction) -> Unit,
+    requestMicPermission: () -> Unit
+) {
+    if (!sstv.hasPermission) {
+        Box(
+            contentAlignment = Alignment.Center,
+            modifier = Modifier.fillMaxSize()
+        ) {
+            Column(
+                horizontalAlignment = Alignment.CenterHorizontally,
+                verticalArrangement = Arrangement.spacedBy(16.dp)
+            ) {
+                Text(text = "🎙️", fontSize = 48.sp)
+                Text(
+                    text = "Microphone access needed",
+                    fontSize = 16.sp,
+                    color = MaterialTheme.colorScheme.onSurface
+                )
+                Button(onClick = requestMicPermission) {
+                    Text("Grant permission")
+                }
+            }
+        }
+        return
+    }
+
+    // Mode selection dialog
+    val showModeDialog = remember { mutableStateOf(false) }
+
+    if (showModeDialog.value) {
+        val allModes = remember(sstv.supportedModes) { listOf("Auto") + sstv.supportedModes }
+        Dialog(onDismissRequest = { showModeDialog.value = false }) {
+            ElevatedCard {
+                Column(
+                    horizontalAlignment = Alignment.CenterHorizontally,
+                    modifier = Modifier.padding(vertical = 16.dp)
+                ) {
+                    Text(
+                        text = "SSTV Mode",
+                        fontSize = 16.sp,
+                        fontWeight = FontWeight.Medium,
+                        color = MaterialTheme.colorScheme.primary,
+                        modifier = Modifier.padding(bottom = 12.dp)
+                    )
+                    LazyColumn(
+                        modifier = Modifier
+                            .fillMaxHeight(0.5f)
+                            .background(MaterialTheme.colorScheme.background),
+                        verticalArrangement = Arrangement.spacedBy(1.dp)
+                    ) {
+                        items(allModes) { mode ->
+                            Row(
+                                verticalAlignment = Alignment.CenterVertically,
+                                modifier = Modifier
+                                    .fillMaxWidth()
+                                    .background(MaterialTheme.colorScheme.surface)
+                                    .clickable {
+                                        onAction(RadarAction.SstvSelectMode(mode))
+                                        showModeDialog.value = false
+                                    }
+                            ) {
+                                Text(
+                                    text = mode,
+                                    fontSize = 16.sp,
+                                    fontWeight = FontWeight.Medium,
+                                    maxLines = 1,
+                                    overflow = TextOverflow.Ellipsis,
+                                    modifier = Modifier
+                                        .weight(1f)
+                                        .padding(start = 16.dp)
+                                )
+                                RadioButton(
+                                    selected = mode == sstv.selectedMode,
+                                    onClick = null,
+                                    modifier = Modifier.padding(horizontal = 16.dp, vertical = 12.dp)
+                                )
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    // Main SSTV view — image fills entire area, controls overlay at bottom
+    Box(
+        modifier = Modifier
+            .fillMaxSize()
+            .background(Color.Black)
+    ) {
+        // Decoded image or placeholder — centered in available space
+        val frame = sstv.currentFrame
+        val pixels = frame?.imagePixels
+        if (pixels != null && frame.imageWidth > 0 && frame.imageHeight > 0) {
+            val bitmap = remember(pixels, frame.imageWidth, frame.imageHeight) {
+                Bitmap.createBitmap(
+                    pixels,
+                    frame.imageWidth,
+                    frame.imageHeight,
+                    Bitmap.Config.ARGB_8888
+                ).asImageBitmap()
+            }
+            Image(
+                bitmap = bitmap,
+                contentDescription = "Decoded SSTV image",
+                contentScale = ContentScale.Fit,
+                modifier = Modifier
+                    .fillMaxSize()
+                    .align(Alignment.Center)
+            )
+        } else {
+            Text(
+                text = if (sstv.status == SstvStatus.Recording) "Listening…" else "No signal",
+                color = MaterialTheme.colorScheme.onSurface,
+                fontSize = 16.sp,
+                modifier = Modifier.align(Alignment.Center)
+            )
+        }
+        // Bottom control bar — dark, blends with the black canvas
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            horizontalArrangement = Arrangement.spacedBy(8.dp),
+            modifier = Modifier
+                .align(Alignment.BottomCenter)
+                .fillMaxWidth()
+                .padding(horizontal = 8.dp, vertical = 8.dp)
+        ) {
+            // Mode button — opens dialog
+            ElevatedCard(
+                modifier = Modifier.weight(1f).height(48.dp),
+                onClick = { showModeDialog.value = true },
+                colors = CardDefaults.elevatedCardColors(
+                    containerColor = MaterialTheme.colorScheme.surface
+                )
+            ) {
+                Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+                    Text(
+                        text = "Mode: ${sstv.selectedMode}",
+                        fontSize = 14.sp,
+                        maxLines = 1,
+                        color = MaterialTheme.colorScheme.onSurface,
+                        modifier = Modifier.infiniteMarquee()
+                    )
+                }
+            }
+            // Reset button — clears decoder state and image
+            IconCard(
+                action = { onAction(RadarAction.SstvReset) },
+                resId = R.drawable.ic_delete
+            )
+            // Save button — always visible, enabled when there are pixels
+            IconCard(
+                action = { onAction(RadarAction.SstvSaveImage) },
+                resId = R.drawable.ic_save,
+                enabled = sstv.currentFrame?.imagePixels != null
+            )
+            // Record / Stop button
+            val playAction = {
+                when (sstv.status) {
+                    SstvStatus.Idle -> onAction(RadarAction.SstvStartRecording)
+                    SstvStatus.Recording -> onAction(RadarAction.SstvStopRecording)
+                    SstvStatus.Saving -> {}
+                }
+            }
+            val playColors = CardDefaults.elevatedCardColors(
+                containerColor = if (sstv.status == SstvStatus.Recording) MaterialTheme.colorScheme.primary
+                else MaterialTheme.colorScheme.surface
+            )
+            val playIcon = if (sstv.status == SstvStatus.Recording) R.drawable.ic_pause else R.drawable.ic_play
+            ElevatedCard(modifier = Modifier.size(48.dp), onClick = playAction, colors = playColors) {
+                Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+                    Icon(painter = painterResource(playIcon), contentDescription = null)
+                }
+            }
+        }
+    }
+}