Added support for Icom IC-705 CAT (#229)

core/data/src/main/java/com/rtbishop/look4sat/core/data/framework/Ic705Controller.kt

@@ -0,0 +1,364 @@
+/*
+ * 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.framework
+
+import android.bluetooth.BluetoothManager
+import android.bluetooth.BluetoothSocket
+import android.util.Log
+import com.rtbishop.look4sat.core.domain.repository.IRadioController
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import kotlinx.coroutines.withContext
+import java.io.InputStream
+import java.io.OutputStream
+import java.util.UUID
+
+/**
+ * Icom IC-705 CI-V controller over Bluetooth SPP.
+ *
+ * The IC-705 emits broadcast frames continuously (band scope, UTC, signal
+ * level, …).  A reply to any command we send may therefore be buried in
+ * that noise.  All response reads drain up to [ACK_TIMEOUT_MS] and scan the
+ * entire accumulated buffer for the frame we expect rather than assuming
+ * the very next byte is the response.
+ */
+class Ic705Controller(
+    private val bluetoothManager: BluetoothManager,
+    private val deviceAddress: String
+) : IRadioController {
+
+    private val tag = "IC705"
+    private val sppId: UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb")
+    private val ioMutex = Mutex()
+
+    /** Time budget (ms) to wait for a response amid broadcast noise. */
+    private val ACK_TIMEOUT_MS = 500L
+    /** Polling interval while draining the input buffer. */
+    private val POLL_INTERVAL_MS = 20L
+    /** Small pause after writing a command before reading the response. */
+    private val WRITE_SETTLE_MS = 50L
+
+    private var socket: BluetoothSocket? = null
+    private var outputStream: OutputStream? = null
+    private var inputStream: InputStream? = null
+
+    override var isConnected: Boolean = false
+        private set
+
+    // ── Connection ──────────────────────────────────────────────────────────
+
+    override suspend fun connect(): Boolean = withContext(Dispatchers.IO) {
+        if (isConnected) return@withContext true
+        if (deviceAddress.isBlank()) return@withContext false
+        try {
+            val device  = bluetoothManager.adapter.getRemoteDevice(deviceAddress)
+            val btSocket = device.createInsecureRfcommSocketToServiceRecord(sppId)
+            btSocket.connect()
+            socket       = btSocket
+            outputStream = btSocket.outputStream
+            inputStream  = btSocket.inputStream
+            isConnected  = true
+            // Enter VFO mode — frequency/mode commands return FA if the radio
+            // is in memory-channel mode. Safe to send regardless of current state.
+            Log.i(tag, "Connected to $deviceAddress — entering VFO mode")
+            val vfoCmd = IcomCivProtocol.buildEnterVfoModeCommand()
+            Log.d(tag, "CMD enterVfoMode → ${IcomCivProtocol.toHex(vfoCmd)}")
+            ioMutex.withLock { sendAndWaitAck(vfoCmd) }
+            true
+        } catch (e: Exception) {
+            Log.e(tag, "Connect error: ${e.message}")
+            isConnected = false
+            false
+        }
+    }
+
+    override suspend fun disconnect() {
+        withContext(Dispatchers.IO) {
+            try {
+                inputStream?.close()
+                outputStream?.close()
+                socket?.close()
+            } catch (e: Exception) {
+                Log.e(tag, "Disconnect error: ${e.message}")
+            } finally {
+                inputStream  = null
+                outputStream = null
+                socket       = null
+                isConnected  = false
+                Log.i(tag, "Disconnected from $deviceAddress")
+            }
+        }
+    }
+
+    // ── IRadioController – standard operations ──────────────────────────────
+
+    override suspend fun setFrequency(frequencyHz: Long): Boolean = withContext(Dispatchers.IO) {
+        Log.d(tag, "setFrequency: ${frequencyHz}Hz")
+        ioMutex.withLock {
+            val cmd = IcomCivProtocol.buildSetFreqCommand(frequencyHz)
+            Log.d(tag, "CMD setFreq → ${IcomCivProtocol.toHex(cmd)}")
+            sendAndWaitAck(cmd)
+        }
+    }
+
+    override suspend fun setMode(mode: String): Boolean = withContext(Dispatchers.IO) {
+        val cmd = IcomCivProtocol.buildSetModeCommand(mode) ?: run {
+            Log.w(tag, "setMode: unknown mode '$mode'")
+            return@withContext false
+        }
+        Log.d(tag, "setMode: $mode")
+        Log.d(tag, "CMD setMode → ${IcomCivProtocol.toHex(cmd)}")
+        ioMutex.withLock { sendAndWaitAck(cmd) }
+    }
+
+    override suspend fun setCtcssMode(enabled: Boolean): Boolean = withContext(Dispatchers.IO) {
+        Log.d(tag, "setCtcssMode: $enabled")
+        val cmd = IcomCivProtocol.buildCtcssModeCommand(enabled)
+        Log.d(tag, "CMD ctcssMode → ${IcomCivProtocol.toHex(cmd)}")
+        ioMutex.withLock { sendAndWaitAck(cmd) }
+    }
+
+    override suspend fun setCtcssTone(toneHz: Double): Boolean = withContext(Dispatchers.IO) {
+        Log.d(tag, "setCtcssTone: ${toneHz}Hz")
+        val cmd = IcomCivProtocol.buildSetCtcssToneCommand(toneHz)
+        Log.d(tag, "CMD ctcssTone → ${IcomCivProtocol.toHex(cmd)}")
+        ioMutex.withLock { sendAndWaitAck(cmd) }
+    }
+
+    override suspend fun readFrequencyAndMode(): Pair<Long, String>? = withContext(Dispatchers.IO) {
+        ioMutex.withLock {
+            val cmd = IcomCivProtocol.buildReadFreqCommand()
+            Log.d(tag, "CMD readFreq → ${IcomCivProtocol.toHex(cmd)}")
+            val payload = sendAndReadResponse(cmd, IcomCivProtocol.CMD_READ_FREQ) ?: return@withContext null
+            // Read-freq reply payload: [cmd byte already stripped by parseResponse] [5 freq bytes] [mode] [filter]
+            IcomCivProtocol.parseFreqModePayload(payload).also {
+                if (it != null) Log.d(tag, "readFreqMode: ${it.first}Hz, ${it.second}")
+                else Log.w(tag, "readFreqMode: parse failed, payload=${IcomCivProtocol.toHex(payload)}")
+            }
+        }
+    }
+
+    override suspend fun pttOn(): Boolean = withContext(Dispatchers.IO) {
+        Log.w(tag, "pttOn: not used for IC-705")
+        true
+    }
+
+    override suspend fun pttOff(): Boolean = withContext(Dispatchers.IO) {
+        Log.w(tag, "pttOff: not used for IC-705")
+        true
+    }
+
+    // ── IRadioController – IC-705 extended operations ───────────────────────
+
+    /** Select the band for [frequencyHz] via CMD 0x1A sub 0x00 (band stacking register). */
+    override suspend fun setBand(frequencyHz: Long): Boolean = withContext(Dispatchers.IO) {
+        val cmd = IcomCivProtocol.buildBandSelectCommand(frequencyHz) ?: run {
+            Log.w(tag, "setBand: no band code for ${frequencyHz}Hz — skipping")
+            return@withContext false
+        }
+        Log.d(tag, "CMD setBand (${frequencyHz}Hz) → ${IcomCivProtocol.toHex(cmd)}")
+        ioMutex.withLock { sendAndWaitAck(cmd) }
+    }
+
+    /** Select VFO-A (main/RX) or VFO-B (sub/TX). */
+    override suspend fun setVfo(vfoA: Boolean): Boolean = withContext(Dispatchers.IO) {
+        val cmd = if (vfoA) IcomCivProtocol.buildSelectVfoACommand()
+                  else      IcomCivProtocol.buildSelectVfoBCommand()
+        Log.d(tag, "CMD selectVFO${if (vfoA) "A" else "B"} → ${IcomCivProtocol.toHex(cmd)}")
+        ioMutex.withLock { sendAndWaitAck(cmd) }
+    }
+
+    /**
+     * Enable or disable SPLIT mode (TX on sub-VFO while listening on main VFO).
+     */
+    override suspend fun setSplitMode(enabled: Boolean): Boolean = withContext(Dispatchers.IO) {
+        val cmd = IcomCivProtocol.buildSplitModeCommand(enabled)
+        Log.d(tag, "CMD split ${if (enabled) "ON" else "OFF"} → ${IcomCivProtocol.toHex(cmd)}")
+        ioMutex.withLock { sendAndWaitAck(cmd) }
+    }
+
+    /**
+     * Set the frequency of the **currently active** VFO (CMD 0x25 sub 0x00).
+     * In split mode the radio automatically switches active VFO on PTT, so
+     * always writing to the active VFO is the correct strategy.
+     */
+    override suspend fun setWorkingFrequency(frequencyHz: Long): Boolean = withContext(Dispatchers.IO) {
+        Log.d(tag, "setWorkingFrequency (0x25/00): ${frequencyHz}Hz")
+        val cmd = IcomCivProtocol.buildSetWorkingFreqCommand(frequencyHz)
+        Log.d(tag, "CMD setWorkingFreq → ${IcomCivProtocol.toHex(cmd)}")
+        ioMutex.withLock { sendAndWaitAck(cmd) }
+    }
+
+    /**
+     * Set TX VFO frequency via CMD 0x25 sub 0x01 (unselected VFO).
+     * Sent every tracking cycle in split mode alongside [setWorkingFrequency].
+     */
+    override suspend fun setTxVfoFrequency(frequencyHz: Long): Boolean = withContext(Dispatchers.IO) {
+        Log.d(tag, "setTxVfoFrequency (0x25/01): ${frequencyHz}Hz")
+        val cmd = IcomCivProtocol.buildSetUnselectedVfoFreqCommand(frequencyHz)
+        Log.d(tag, "CMD setTxVfoFreq → ${IcomCivProtocol.toHex(cmd)}")
+        ioMutex.withLock { sendAndWaitAck(cmd) }
+    }
+
+    /**
+     * Read the frequency of the currently active VFO (CMD 0x25 sub 0x00).
+     * Used for tuning detection in split mode.
+     */
+    override suspend fun readWorkingFrequency(): Long? = withContext(Dispatchers.IO) {
+        ioMutex.withLock {
+            val cmd = IcomCivProtocol.buildReadWorkingFreqCommand()
+            Log.d(tag, "CMD readWorkingFreq → ${IcomCivProtocol.toHex(cmd)}")
+            val payload = sendAndReadResponse(cmd, IcomCivProtocol.CMD_SELECTED_VFO_FREQ) ?: return@withContext null
+            // Response payload: [sub] [5 freq bytes] — CMD byte already stripped by parseResponse
+            Log.d(tag, "readWorkingFreq: got ${payload.size} bytes: ${IcomCivProtocol.toHex(payload)}")
+            if (payload.size < 6) {
+                Log.w(tag, "readWorkingFreq: payload too short (${payload.size} bytes)")
+                return@withContext null
+            }
+            val freqBcd = payload.sliceArray(1..5)
+            val freq = IcomCivProtocol.decodeFrequencyBcd(freqBcd)
+            Log.d(tag, "readWorkingFreq: ${freq}Hz")
+            freq
+        }
+    }
+
+    /**
+     * Read the frequency of the inactive/TX VFO (CMD 0x25 sub 0x01).
+     * Used for tuning detection in split mode.
+     */
+    override suspend fun readTxVfoFrequency(): Long? = withContext(Dispatchers.IO) {
+        ioMutex.withLock {
+            val cmd = IcomCivProtocol.buildReadTxVfoFreqCommand()
+            Log.d(tag, "CMD readTxVfoFreq → ${IcomCivProtocol.toHex(cmd)}")
+            val payload = sendAndReadResponse(cmd, IcomCivProtocol.CMD_SELECTED_VFO_FREQ) ?: return@withContext null
+            // Response payload: [sub] [5 freq bytes] — CMD byte already stripped by parseResponse
+            Log.d(tag, "readTxVfoFreq: got ${payload.size} bytes: ${IcomCivProtocol.toHex(payload)}")
+            if (payload.size < 6) {
+                Log.w(tag, "readTxVfoFreq: payload too short (${payload.size} bytes)")
+                return@withContext null
+            }
+            val freqBcd = payload.sliceArray(1..5)
+            val freq = IcomCivProtocol.decodeFrequencyBcd(freqBcd)
+            Log.d(tag, "readTxVfoFreq: ${freq}Hz")
+            freq
+        }
+    }
+
+    // ── Internal I/O helpers ────────────────────────────────────────────────
+
+    /**
+     * Write [cmd] to the radio and drain the input stream for up to
+     * [ACK_TIMEOUT_MS], looking for an OK/NG acknowledgement frame.
+     */
+    private suspend fun sendAndWaitAck(cmd: ByteArray): Boolean {
+        if (!write(cmd)) return false
+        delay(WRITE_SETTLE_MS)
+        val buf = drainWithTimeout(ACK_TIMEOUT_MS)
+        val ok  = IcomCivProtocol.containsAck(buf)
+        if (!ok) Log.w(tag, "ACK not found in ${buf.size} bytes: ${IcomCivProtocol.toHex(buf)}")
+        return ok
+    }
+
+    /**
+     * Write [cmd] to the radio and drain the input stream for up to
+     * [ACK_TIMEOUT_MS], scanning for a response frame carrying [expectCmd].
+     * Returns the payload bytes of that frame, or null on timeout/error.
+     */
+    private suspend fun sendAndReadResponse(cmd: ByteArray, expectCmd: Byte): ByteArray? {
+        if (!write(cmd)) return null
+        delay(WRITE_SETTLE_MS)
+        val buf      = drainWithTimeout(ACK_TIMEOUT_MS)
+        val response = IcomCivProtocol.parseResponse(buf, expectCmd)
+        if (response == null) {
+            Log.w(tag, "No response for cmd 0x${String.format("%02X", expectCmd.toInt() and 0xFF)} " +
+                    "in ${buf.size} bytes: ${IcomCivProtocol.toHex(buf)}")
+        }
+        return response?.payload
+    }
+
+    /**
+     * Drain whatever bytes the radio has buffered within a [timeoutMs] window.
+     * Exits early as soon as a complete CI-V frame addressed to us is present
+     * in the buffer (i.e., FE FE E0 A4 … FD), so we don't waste the remaining
+     * timeout on responses that already arrived.
+     */
+    private suspend fun drainWithTimeout(timeoutMs: Long): ByteArray {
+        val result   = mutableListOf<Byte>()
+        val deadline = System.currentTimeMillis() + timeoutMs
+        val stream   = inputStream ?: return ByteArray(0)
+        while (System.currentTimeMillis() < deadline) {
+            try {
+                val available = stream.available()
+                if (available > 0) {
+                    val chunk = ByteArray(available)
+                    val read  = stream.read(chunk)
+                    if (read > 0) {
+                        result.addAll(chunk.take(read))
+                        // Exit early once we have a complete frame for us
+                        if (hasCompleteFrameForUs(result)) break
+                    }
+                } else {
+                    delay(POLL_INTERVAL_MS)
+                }
+            } catch (e: Exception) {
+                Log.e(tag, "Drain error: ${e.message}")
+                isConnected = false
+                break
+            }
+        }
+        return result.toByteArray()
+    }
+
+    /**
+     * Returns true if [buf] contains a complete CI-V frame addressed to the
+     * controller (FE FE [ADDR_CTRL] [ADDR_IC705] … FD).
+     * CI-V data bytes cannot be 0xFD, so the first 0xFD after the header is
+     * always the frame terminator.
+     */
+    private fun hasCompleteFrameForUs(buf: List<Byte>): Boolean {
+        var i = 0
+        while (i < buf.size - 4) {
+            if (buf[i]     == IcomCivProtocol.PREAMBLE    &&
+                buf[i + 1] == IcomCivProtocol.PREAMBLE    &&
+                buf[i + 2] == IcomCivProtocol.ADDR_CTRL   &&
+                buf[i + 3] == IcomCivProtocol.ADDR_IC705
+            ) {
+                for (k in i + 4 until buf.size) {
+                    if (buf[k] == IcomCivProtocol.END_OF_MSG) return true
+                }
+                return false  // header found but no FD yet
+            }
+            i++
+        }
+        return false
+    }
+
+    private fun write(bytes: ByteArray): Boolean {
+        return try {
+            outputStream?.write(bytes)
+            outputStream?.flush()
+            true
+        } catch (e: Exception) {
+            Log.e(tag, "Write error: ${e.message}")
+            isConnected = false
+            false
+        }
+    }
+}

core/data/src/main/java/com/rtbishop/look4sat/core/data/framework/IcomCivProtocol.kt

@@ -0,0 +1,352 @@
+/*
+ * 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.framework
+
+import java.util.Locale
+
+/**
+ * Icom CI-V protocol encoder/decoder for the IC-705.
+ *
+ * Frame structure:
+ *   FE FE <DEST> <SRC> <CMD> [<SUB>] [<DATA...>] FD
+ *
+ * IC-705 default CI-V address : 0xA4
+ * Controller (us) address     : 0xE0
+ */
+object IcomCivProtocol {
+
+    // ── Framing constants ──────────────────────────────────────────────────
+    const val PREAMBLE: Byte      = 0xFE.toByte()
+    const val END_OF_MSG: Byte    = 0xFD.toByte()
+    const val ACK_OK: Byte        = 0xFB.toByte()
+    const val ACK_NG: Byte        = 0xFA.toByte()
+
+    // ── Address constants ──────────────────────────────────────────────────
+    /** Default CI-V address of the IC-705. */
+    const val ADDR_IC705: Byte    = 0xA4.toByte()
+    /** Default CI-V address of the controller (us). */
+    const val ADDR_CTRL: Byte     = 0xE0.toByte()
+
+    // ── Command bytes ──────────────────────────────────────────────────────
+    /** Read operating frequency (main VFO). */
+    const val CMD_READ_FREQ: Byte           = 0x03
+    /** Set operating frequency (main VFO). */
+    const val CMD_SET_FREQ: Byte            = 0x05
+    /** Set operating mode. */
+    const val CMD_SET_MODE: Byte            = 0x06
+    /** Select VFO / memory. */
+    const val CMD_SELECT_VFO: Byte          = 0x07
+    /**
+     * Select operating mode (VFO vs memory-channel).
+     * Sub 0x00 = VFO mode. Must be sent after connect if the radio is in
+     * memory-channel mode — frequency/mode commands return FA until it is.
+     */
+    const val CMD_SELECT_OP_MODE: Byte      = 0x08
+    /** Set repeater duplex / SPLIT. */
+    const val CMD_DUPLEX_SPLIT: Byte        = 0x0F
+    /** Band stacking register / band select (sub 0x00 = select, data = BCD band number). */
+    const val CMD_BAND_SELECT: Byte         = 0x1A
+    /** Read/write CTCSS tone frequency. */
+    const val CMD_CTCSS_TONE: Byte          = 0x1B
+    /** Read/write misc settings (used for enabling CTCSS encode). */
+    const val CMD_MISC_SETTING: Byte        = 0x16
+    /** Read/write selected-VFO frequency (cmd 0x25). */
+    const val CMD_SELECTED_VFO_FREQ: Byte   = 0x25
+
+    // ── Sub-command bytes ──────────────────────────────────────────────────
+    /** Sub for CMD_SELECT_VFO: select VFO-A (main). */
+    const val SUB_VFO_A: Byte   = 0x00
+    /** Sub for CMD_SELECT_VFO: select VFO-B (sub). */
+    const val SUB_VFO_B: Byte   = 0x01
+    /** Sub for CMD_DUPLEX_SPLIT: simplex / split OFF. */
+    const val SUB_SPLIT_OFF: Byte = 0x00
+    /** Sub for CMD_DUPLEX_SPLIT: SPLIT ON. */
+    const val SUB_SPLIT_ON: Byte  = 0x01
+    /** Sub for CMD_SELECTED_VFO_FREQ: selected (active) VFO frequency. */
+    const val SUB_SELECTED_VFO: Byte = 0x00
+    /** Sub for CMD_SELECTED_VFO_FREQ: unselected (inactive / TX in split) VFO frequency. */
+    const val SUB_UNSELECTED_VFO: Byte = 0x01
+    /** Sub for CMD_MISC_SETTING: CTCSS/DTCS tone squelch. */
+    const val SUB_CTCSS_SETTING: Byte = 0x42.toByte()
+
+    // ── Mode bytes ────────────────────────────────────────────────────────
+    /** Maps mode strings (upper-case) → IC-705 mode bytes. */
+    val MODE_TO_BYTE: Map<String, Byte> = mapOf(
+        "LSB"    to 0x00,
+        "USB"    to 0x01,
+        "AM"     to 0x02,
+        "CW"     to 0x03,
+        "RTTY"   to 0x04,
+        "FM"     to 0x05,
+        "WFM"    to 0x06,
+        "CW-R"   to 0x07,
+        "RTTY-R" to 0x08,
+        "DV"     to 0x12,
+        "AFSK"   to 0x05  // AFSK uses FM modulation
+    )
+
+    val BYTE_TO_MODE: Map<Byte, String> = MODE_TO_BYTE.entries.associate { it.value to it.key }
+
+    // ── Frequency BCD encoding ─────────────────────────────────────────────
+
+    /**
+     * Encode a frequency in Hz to the IC-705's 5-byte BCD format.
+     *
+     * The IC-705 uses 5 bytes, LSB pair first, with 1 Hz resolution.
+     * Example: 145,500,000 Hz → "0145500000" → pairs LSB→MSB:
+     *   [00, 00, 50, 45, 01]
+     */
+    fun encodeFrequencyBcd(frequencyHz: Long): ByteArray {
+        val digits = String.format(Locale.US, "%010d", frequencyHz)
+        val bcd = ByteArray(5)
+        for (i in 0 until 5) {
+            // digits are MSB first; we want pair index 0 = LSB pair
+            val pairIndex = 4 - i
+            val high = digits[pairIndex * 2] - '0'
+            val low  = digits[pairIndex * 2 + 1] - '0'
+            bcd[i] = ((high shl 4) or low).toByte()
+        }
+        return bcd
+    }
+
+    /**
+     * Decode 5-byte BCD frequency (LSB pair first) to Hz.
+     */
+    fun decodeFrequencyBcd(bcd: ByteArray): Long {
+        // Build digit string MSB→LSB by reversing the byte order
+        var freqHz = 0L
+        for (i in 4 downTo 0) {
+            val b    = bcd[i].toInt() and 0xFF
+            val high = b shr 4
+            val low  = b and 0x0F
+            freqHz   = freqHz * 100 + high * 10 + low
+        }
+        return freqHz
+    }
+
+    /**
+     * Encode a CTCSS tone (Hz, e.g. 67.0) to 2-byte BCD (0.1 Hz resolution).
+     * 67.0 → 670 (tenths of Hz) → BCD bytes [0x06, 0x70].
+     */
+    fun encodeCtcssToneBcd(toneHz: Double): ByteArray {
+        val tone01 = (toneHz * 10).toLong()
+        val digits = String.format(Locale.US, "%04d", tone01)
+        return byteArrayOf(
+            ((digits[0] - '0') shl 4 or (digits[1] - '0')).toByte(),
+            ((digits[2] - '0') shl 4 or (digits[3] - '0')).toByte()
+        )
+    }
+
+    // ── Message builders ───────────────────────────────────────────────────
+
+    /** Wrap payload bytes in a CI-V frame: FE FE DEST SRC ... FD. */
+    private fun frame(vararg payload: Byte): ByteArray {
+        return byteArrayOf(PREAMBLE, PREAMBLE, ADDR_IC705, ADDR_CTRL) +
+                payload +
+                byteArrayOf(END_OF_MSG)
+    }
+
+    /** Set operating frequency via CMD 0x05 (main VFO). */
+    fun buildSetFreqCommand(frequencyHz: Long): ByteArray {
+        return frame(CMD_SET_FREQ, *encodeFrequencyBcd(frequencyHz))
+    }
+
+    /**
+     * Set selected-VFO frequency via CMD 0x25 sub 0x00.
+     * This updates whichever VFO is currently active (RX or TX after split).
+     */
+    fun buildSetWorkingFreqCommand(frequencyHz: Long): ByteArray {
+        return frame(CMD_SELECTED_VFO_FREQ, SUB_SELECTED_VFO, *encodeFrequencyBcd(frequencyHz))
+    }
+
+    /**
+     * Set unselected-VFO frequency via CMD 0x25 sub 0x01.
+     * In split mode while PTT is pressed the IC-705 makes VFO-B active, so
+     * this command targets VFO-A (the RX VFO) — and vice-versa when in RX.
+     * Use this to update the TX VFO when PTT is on.
+     */
+    fun buildSetUnselectedVfoFreqCommand(frequencyHz: Long): ByteArray {
+        return frame(CMD_SELECTED_VFO_FREQ, SUB_UNSELECTED_VFO, *encodeFrequencyBcd(frequencyHz))
+    }
+
+    /** Read operating frequency (CMD 0x03). */
+    fun buildReadFreqCommand(): ByteArray = frame(CMD_READ_FREQ)
+
+    /** Read selected (active) VFO frequency (CMD 0x25 sub 0x00). */
+    fun buildReadWorkingFreqCommand(): ByteArray = frame(CMD_SELECTED_VFO_FREQ, SUB_SELECTED_VFO)
+
+    /** Read unselected (inactive/TX in split) VFO frequency (CMD 0x25 sub 0x01). */
+    fun buildReadTxVfoFreqCommand(): ByteArray = frame(CMD_SELECTED_VFO_FREQ, SUB_UNSELECTED_VFO)
+
+    /**
+     * Select band via CMD 0x1A sub 0x00.
+     * Band codes are BCD-numbered: 1=160m, 2=80m, …, 9=10m, 0x10=6m, 0x11=2m, 0x12=70cm, 0x13=23cm.
+     * Returns null if [frequencyHz] doesn't fall in a known amateur band.
+     */
+    fun buildBandSelectCommand(frequencyHz: Long): ByteArray? {
+        val code = bandCodeForFrequency(frequencyHz) ?: return null
+        return frame(CMD_BAND_SELECT, 0x00, code)
+    }
+
+    /**
+     * Map a frequency in Hz to the IC-705 band stacking register code.
+     * Codes are BCD (band number in decimal expressed as hex nibbles).
+     */
+    fun bandCodeForFrequency(frequencyHz: Long): Byte? = when {
+        frequencyHz in 1_800_000L     ..1_999_999L     -> 0x01 // 160 m
+        frequencyHz in 3_500_000L     ..3_999_999L     -> 0x02 // 80 m
+        frequencyHz in 7_000_000L     ..7_299_999L     -> 0x03 // 40 m
+        frequencyHz in 10_100_000L    ..10_149_999L    -> 0x04 // 30 m
+        frequencyHz in 14_000_000L    ..14_349_999L    -> 0x05 // 20 m
+        frequencyHz in 18_068_000L    ..18_167_999L    -> 0x06 // 17 m
+        frequencyHz in 21_000_000L    ..21_449_999L    -> 0x07 // 15 m
+        frequencyHz in 24_890_000L    ..24_989_999L    -> 0x08 // 12 m
+        frequencyHz in 28_000_000L    ..29_699_999L    -> 0x09 // 10 m
+        frequencyHz in 50_000_000L    ..53_999_999L    -> 0x10 // 6 m  (BCD 10)
+        frequencyHz in 144_000_000L   ..147_999_999L   -> 0x11 // 2 m  (BCD 11)
+        frequencyHz in 420_000_000L   ..449_999_999L   -> 0x12 // 70 cm (BCD 12)
+        frequencyHz in 1_240_000_000L ..1_299_999_999L -> 0x13 // 23 cm (BCD 13)
+        else -> null
+    }
+
+    /** Set operating mode (CMD 0x06). Filter byte is omitted — radio uses its default filter for the mode. */
+    fun buildSetModeCommand(mode: String): ByteArray? {
+        val modeByte = MODE_TO_BYTE[mode.uppercase(Locale.US)] ?: return null
+        return frame(CMD_SET_MODE, modeByte)
+    }
+
+    /** Select VFO-A (CMD 0x07 sub 0x00). */
+    fun buildSelectVfoACommand(): ByteArray = frame(CMD_SELECT_VFO, SUB_VFO_A)
+
+    /** Select VFO-B (CMD 0x07 sub 0x01). */
+    fun buildSelectVfoBCommand(): ByteArray = frame(CMD_SELECT_VFO, SUB_VFO_B)
+
+    /**
+     * Enter VFO operating mode (CMD 0x08 sub 0x00).
+     * Sent after connect — if the radio is in memory-channel mode frequency
+     * and mode commands return FA until this is issued.
+     */
+    fun buildEnterVfoModeCommand(): ByteArray = frame(CMD_SELECT_OP_MODE, 0x00)
+
+    /** Enable or disable SPLIT mode (CMD 0x0F). */
+    fun buildSplitModeCommand(enable: Boolean): ByteArray {
+        val sub = if (enable) SUB_SPLIT_ON else SUB_SPLIT_OFF
+        return frame(CMD_DUPLEX_SPLIT, sub)
+    }
+
+    /**
+     * Enable/disable CTCSS encode (CMD 0x16 sub 0x42).
+     * 0x01 = CTCSS encoder ON, 0x00 = OFF.
+     */
+    fun buildCtcssModeCommand(enabled: Boolean): ByteArray {
+        val value: Byte = if (enabled) 0x01 else 0x00
+        return frame(CMD_MISC_SETTING, SUB_CTCSS_SETTING, value)
+    }
+
+    /**
+     * Set CTCSS tone frequency (CMD 0x1B sub 0x00).
+     */
+    fun buildSetCtcssToneCommand(toneHz: Double): ByteArray {
+        val bcd = encodeCtcssToneBcd(toneHz)
+        return frame(CMD_CTCSS_TONE, 0x00, *bcd)
+    }
+
+    // ── Response parsing ───────────────────────────────────────────────────
+
+    /**
+     * Find and parse a complete CI-V response frame from a buffer.
+     *
+     * Returns the bytes between "FE FE E0 A4 <CMD>" and FD, or null if no
+     * complete frame was found. The search is tolerant of interleaved
+     * broadcast traffic.
+     *
+     * @param buf       bytes accumulated from the radio
+     * @param expectCmd the command byte we are looking for in the reply, or
+     *                  null to accept any command response from the radio
+     */
+    fun parseResponse(buf: ByteArray, expectCmd: Byte?): ParsedResponse? {
+        var i = 0
+        while (i < buf.size - 5) {
+            // Look for FE FE preamble
+            if (buf[i] != PREAMBLE || buf[i + 1] != PREAMBLE) { i++; continue }
+            val dest = buf[i + 2]
+            val src  = buf[i + 3]
+            val cmd  = buf[i + 4]
+            // We only care about frames addressed to us from the radio
+            if (dest != ADDR_CTRL || src != ADDR_IC705) { i++; continue }
+            // Find the terminating FD
+            val fdIdx = buf.indexOf(END_OF_MSG, startIndex = i + 5)
+            if (fdIdx < 0) break  // incomplete frame, wait for more data
+            val payload = buf.copyOfRange(i + 5, fdIdx)
+            if (expectCmd == null || cmd == expectCmd) {
+                return ParsedResponse(cmd, payload, fdIdx + 1)
+            }
+            i = fdIdx + 1
+        }
+        return null
+    }
+
+    private fun ByteArray.indexOf(b: Byte, startIndex: Int): Int {
+        for (k in startIndex until size) if (this[k] == b) return k
+        return -1
+    }
+
+    /**
+     * Check whether a buffer contains an OK acknowledgement (FB FD) from
+     * the radio. Tolerates broadcast noise before the ACK.
+     */
+    fun containsAck(buf: ByteArray): Boolean {
+        var i = 0
+        while (i < buf.size - 5) {
+            if (buf[i] != PREAMBLE || buf[i + 1] != PREAMBLE) { i++; continue }
+            val dest = buf[i + 2]
+            val src  = buf[i + 3]
+            val cmd  = buf[i + 4]
+            if (dest != ADDR_CTRL || src != ADDR_IC705) { i++; continue }
+            // Skip to FD
+            val fdIdx = buf.indexOf(END_OF_MSG, startIndex = i + 5)
+            if (fdIdx < 0) break
+            if (cmd == ACK_OK) return true
+            if (cmd == ACK_NG) return false
+            i = fdIdx + 1
+        }
+        return false
+    }
+
+    /**
+     * Parse frequency + mode from a CMD_READ_FREQ reply payload.
+     * Payload layout after stripping command byte: [5 freq bytes] [mode byte] [filter byte]
+     */
+    fun parseFreqModePayload(payload: ByteArray): Pair<Long, String>? {
+        if (payload.size < 6) return null
+        val freqHz = decodeFrequencyBcd(payload.copyOfRange(0, 5))
+        val mode   = BYTE_TO_MODE[payload[5]] ?: return null
+        return freqHz to mode
+    }
+
+    /** Hex dump of bytes, useful for debug logging. */
+    fun toHex(bytes: ByteArray): String =
+        bytes.joinToString(" ") { String.format(Locale.US, "%02X", it.toInt() and 0xFF) }
+
+    data class ParsedResponse(
+        val cmd: Byte,
+        val payload: ByteArray,
+        /** Index in the source buffer immediately after the FD terminator. */
+        val nextOffset: Int
+    )
+}

core/data/src/main/java/com/rtbishop/look4sat/core/data/framework/RadioTrackingService.kt

@@ -19,8 +19,10 @@ package com.rtbishop.look4sat.core.data.framework
 
 import android.bluetooth.BluetoothManager
 import android.util.Log
+import com.rtbishop.look4sat.core.domain.model.RadioControlSettings
 import com.rtbishop.look4sat.core.domain.model.SatRadio
 import com.rtbishop.look4sat.core.domain.predict.OrbitalPass
+import com.rtbishop.look4sat.core.domain.predict.SPEED_OF_LIGHT
 import com.rtbishop.look4sat.core.domain.repository.IRadioController
 import com.rtbishop.look4sat.core.domain.repository.IRadioTrackingService
 import com.rtbishop.look4sat.core.domain.repository.ISatelliteRepo
@@ -29,6 +31,7 @@ import com.rtbishop.look4sat.core.domain.repository.RadioTrackingState
 import com.rtbishop.look4sat.core.domain.utility.TransponderMapper
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
+import kotlinx.coroutines.currentCoroutineContext
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -44,6 +47,8 @@ class RadioTrackingService(
 ) : IRadioTrackingService {
 
     private val tag = "RadioTracking"
+    /** Delay between each step of the split-mode init sequence (ms). */
+    private val INIT_STEP_DELAY_MS = 200L
     private val _state = MutableStateFlow(RadioTrackingState())
     override val state: StateFlow<RadioTrackingState> = _state
 
@@ -51,28 +56,48 @@ class RadioTrackingService(
     private var rxController: IRadioController? = null
     private var trackingJob: Job? = null
 
+    // ── Connection ──────────────────────────────────────────────────────────
+
     override suspend fun connectRadios() {
-        // Disconnect old controllers if any
         txController?.disconnect()
         rxController?.disconnect()
 
-        // Read current addresses from settings
         val rcSettings = settingsRepo.radioControlSettings.value
         val txAddr     = rcSettings.txRadioAddress
         val rxAddr     = rcSettings.rxRadioAddress
+        val isIcom     = rcSettings.radioModel == RadioControlSettings.MODEL_ICOM_IC705
+        val isSplit    = isIcom && rcSettings.splitMode
 
-        Log.i(tag, "Connecting TX=$txAddr RX=$rxAddr")
+        Log.i(tag, "connectRadios model=${rcSettings.radioModel} split=$isSplit TX=$txAddr RX=$rxAddr")
 
+        if (isSplit) {
+            // Single-radio split mode: only TX slot is used
+            if (txAddr.isBlank()) {
+                _state.update { it.copy(errorMessage = "No radio address configured in Settings") }
+                return
+            }
+            val tx = makeController(isIcom, txAddr)
+            txController = tx
+            rxController = null
+            _state.update { it.copy(errorMessage = null) }
+            val txOk = tx.connect()
+            _state.update {
+                it.copy(
+                    txConnected = txOk,
+                    rxConnected = false,
+                    errorMessage = if (!txOk) "Could not connect to radio ($txAddr)" else null
+                )
+            }
+            Log.i(tag, "IC-705 split mode connected: txOk=$txOk")
+        } else {
             if (txAddr.isBlank() && rxAddr.isBlank()) {
                 _state.update { it.copy(errorMessage = "No radio addresses configured in Settings") }
                 return
             }
-
+            val tx = makeController(isIcom, txAddr)
-        val tx = Ft817Controller(bluetoothManager, txAddr)
+            val rx = makeController(isIcom, rxAddr)
-        val rx = Ft817Controller(bluetoothManager, rxAddr)
             txController = tx
             rxController = rx
-
             _state.update { it.copy(errorMessage = null) }
             val txOk = if (txAddr.isNotBlank()) tx.connect() else false
             val rxOk = if (rxAddr.isNotBlank()) rx.connect() else false
@@ -88,7 +113,13 @@ class RadioTrackingService(
                     }
                 )
             }
+            Log.i(tag, "Dual-radio connected: txOk=$txOk rxOk=$rxOk")
         }
+    }
+
+    private fun makeController(isIcom: Boolean, address: String): IRadioController =
+        if (isIcom) Ic705Controller(bluetoothManager, address)
+        else        Ft817Controller(bluetoothManager, address)
 
     override suspend fun disconnectRadios() {
         stopTracking()
@@ -96,15 +127,11 @@ class RadioTrackingService(
         rxController?.disconnect()
         txController = null
         rxController = null
-        _state.update {
+        _state.update { it.copy(txConnected = false, rxConnected = false, isActive = false) }
-            it.copy(
-                txConnected = false,
-                rxConnected = false,
-                isActive = false
-            )
-        }
     }
 
+    // ── Tracking ────────────────────────────────────────────────────────────
+
     override fun startTracking(pass: OrbitalPass, transponder: SatRadio, txBaseFreqHz: Long?) {
         _state.update {
             it.copy(
@@ -115,26 +142,44 @@ class RadioTrackingService(
             )
         }
         trackingJob?.cancel()
-        trackingJob = appScope.launch {
+
-            // Set modes on both radios at tracking start
+        val rcSettings = settingsRepo.radioControlSettings.value
+        val isIcom     = rcSettings.radioModel == RadioControlSettings.MODEL_ICOM_IC705
+        val isSplit    = isIcom && rcSettings.splitMode
+
+        if (isSplit) {
+            trackingJob = appScope.launch { runSplitTracking(transponder, txBaseFreqHz) }
+        } else {
+            trackingJob = appScope.launch { runDualRadioTracking(transponder, txBaseFreqHz) }
+        }
+    }
+
+    // ── Dual-radio tracking (Yaesu or two IC-705s) ──────────────────────────
+
+    private suspend fun runDualRadioTracking(transponder: SatRadio, initialTxBaseFreqHz: Long?) {
         val tx = txController
         val rx = rxController
+
+        // Initial setup: set band/mode/CTCSS on both radios
         val txMode = transponder.uplinkMode
         val rxMode = transponder.downlinkMode
             ?: transponder.uplinkMode?.let {
                 TransponderMapper.mapUplinkModeToDownlinkMode(it, transponder.isInverted)
             }
+
+        Log.i(tag, "DualRadio start: txMode=$txMode rxMode=$rxMode")
+
         if (tx != null && tx.isConnected && txMode != null) {
+            Log.d(tag, "Setting TX mode: $txMode")
             tx.setMode(txMode)
-                Log.i(tag, "TX mode set to $txMode")
         }
         if (rx != null && rx.isConnected && rxMode != null) {
+            Log.d(tag, "Setting RX mode: $rxMode")
             rx.setMode(rxMode)
-                Log.i(tag, "RX mode set to $rxMode")
         }
-            // Set CTCSS if FM
         if (txMode?.uppercase() == "FM") {
             _state.value.ctcssTone?.let { tone ->
+                Log.d(tag, "Setting CTCSS: ${tone}Hz")
                 tx?.setCtcssTone(tone)
                 tx?.setCtcssMode(true)
             }
@@ -143,11 +188,11 @@ class RadioTrackingService(
 
         var lastSetTxFreq = 0.0
         var lastSetRxFreq = 0.0
-            var tuningRadio = "" // "", "tx", or "rx" - which radio the user is tuning
+        var tuningRadio   = ""
         var lastReadFreq  = 0L
         var stableCount   = 0
 
-            while (isActive) {
+        while (currentCoroutineContext().isActive) {
             val currentState = _state.value
             if (!currentState.isActive) break
 
@@ -155,39 +200,29 @@ class RadioTrackingService(
             val xpdr    = currentState.selectedTransponder ?: break
             var txBaseFreq = currentState.txBaseFrequencyHz
             val stationPos = settingsRepo.stationPosition.value
-                val timeNow = System.currentTimeMillis()
+            val pos = satelliteRepo.getPosition(satPass.orbitalObject, stationPos, System.currentTimeMillis())
-
+            val txNow = txController
-                val pos = satelliteRepo.getPosition(satPass.orbitalObject, stationPos, timeNow)
+            val rxNow = rxController
-                val tx = txController
-                val rx = rxController
-                val hasUplink = txBaseFreq != null
-                val c = com.rtbishop.look4sat.core.domain.predict.SPEED_OF_LIGHT
             val v = pos.distanceRate * 1000.0
 
             if (tuningRadio.isNotEmpty()) {
-                    // --- User is tuning: keep reading, wait for stabilization ---
+                val radio = if (tuningRadio == "tx") txNow else rxNow
-                    val radio = if (tuningRadio == "tx") tx else rx
                 if (radio != null && radio.isConnected) {
-                        val readResult = radio.readFrequencyAndMode()
+                    val read = radio.readFrequencyAndMode()
-                        if (readResult != null) {
+                    if (read != null) {
-                            val (freq, _) = readResult
+                        val (freq, _) = read
-                            if (kotlin.math.abs(freq - lastReadFreq) <= 20) {
+                        if (kotlin.math.abs(freq - lastReadFreq) <= 20) stableCount++
-                                stableCount++
+                        else { stableCount = 0; lastReadFreq = freq }
-                            } else {
-                                stableCount = 0
-                                lastReadFreq = freq
-                            }
-                            // Stable for 2 reads → user stopped turning
                         if (stableCount >= 2) {
                             if (tuningRadio == "tx" && txBaseFreq != null) {
-                                    val newBase = (freq.toDouble() * c / (c + v)).toLong()
+                                val newBase = (freq.toDouble() * SPEED_OF_LIGHT / (SPEED_OF_LIGHT + v)).toLong()
                                 if (newBase > 0) {
                                     txBaseFreq = newBase
                                     _state.update { it.copy(txBaseFrequencyHz = newBase) }
                                     Log.i(tag, "TX tuning done → base=$newBase")
                                 }
                             } else if (tuningRadio == "rx") {
-                                    val rxNominal = (freq.toDouble() * c / (c - v)).toLong()
+                                val rxNominal = (freq.toDouble() * SPEED_OF_LIGHT / (SPEED_OF_LIGHT - v)).toLong()
                                 val newTxBase = TransponderMapper.mapDownlinkToUplink(rxNominal, xpdr)
                                 if (newTxBase != null && newTxBase > 0) {
                                     txBaseFreq = newTxBase
@@ -203,62 +238,48 @@ class RadioTrackingService(
                     }
                 }
             } else {
-                    // --- Normal tracking: read, detect changes, command ---
+                // Detect manual dial changes
-
+                if (txBaseFreq != null && txNow != null && txNow.isConnected && lastSetTxFreq > 0.0) {
-                    // TX dial feedback
+                    val read = txNow.readFrequencyAndMode()
-                    if (hasUplink && tx != null && tx.isConnected && lastSetTxFreq > 0.0) {
+                    if (read != null && kotlin.math.abs(read.first - lastSetTxFreq) >= 20.0) {
-                        val readResult = tx.readFrequencyAndMode()
-                        if (readResult != null) {
-                            val (actualTxFreq, _) = readResult
-                            if (kotlin.math.abs(actualTxFreq - lastSetTxFreq) >= 20.0) {
                         tuningRadio  = "tx"
-                                lastReadFreq = actualTxFreq
+                        lastReadFreq = read.first
                         stableCount  = 0
-                                Log.i(tag, "TX tuning detected (read=$actualTxFreq, lastSet=$lastSetTxFreq)")
+                        Log.i(tag, "TX tuning detected (read=${read.first}, lastSet=$lastSetTxFreq)")
                     }
                 }
-                    }
+                if (tuningRadio.isEmpty() && rxNow != null && rxNow.isConnected && lastSetRxFreq > 0.0) {
-
+                    val read = rxNow.readFrequencyAndMode()
-                    // RX dial feedback (only if TX not tuning)
+                    if (read != null && kotlin.math.abs(read.first - lastSetRxFreq) >= 20.0) {
-                    if (tuningRadio.isEmpty() && rx != null && rx.isConnected && lastSetRxFreq > 0.0) {
-                        val readResult = rx.readFrequencyAndMode()
-                        if (readResult != null) {
-                            val (actualRxFreq, _) = readResult
-                            if (kotlin.math.abs(actualRxFreq - lastSetRxFreq) >= 20.0) {
                         tuningRadio  = "rx"
-                                lastReadFreq = actualRxFreq
+                        lastReadFreq = read.first
                         stableCount  = 0
-                                Log.i(tag, "RX tuning detected (read=$actualRxFreq, lastSet=$lastSetRxFreq)")
+                        Log.i(tag, "RX tuning detected (read=${read.first}, lastSet=$lastSetRxFreq)")
-                            }
                     }
                 }
             }
 
-                // Compute Doppler-corrected frequencies
             val txRadioFreq = txBaseFreq?.let { pos.getUplinkFreq(it) }
             val rxBaseFreq  = if (txBaseFreq != null) {
                 TransponderMapper.mapUplinkToDownlink(txBaseFreq, xpdr)
-                } else {
+            } else xpdr.downlinkLow
-                    xpdr.downlinkLow
-                }
             val rxRadioFreq = rxBaseFreq?.let { pos.getDownlinkFreq(it) }
 
-                // Command radios (only when not tuning)
             if (tuningRadio.isEmpty()) {
-                    if (tx != null && tx.isConnected && txRadioFreq != null) {
+                if (txNow != null && txNow.isConnected && txRadioFreq != null) {
-                        tx.setFrequency(txRadioFreq)
+                    txNow.setFrequency(txRadioFreq)
                     lastSetTxFreq = txRadioFreq.toDouble()
                 }
-                    if (rx != null && rx.isConnected && rxRadioFreq != null) {
+                if (rxNow != null && rxNow.isConnected && rxRadioFreq != null) {
-                        rx.setFrequency(rxRadioFreq)
+                    rxNow.setFrequency(rxRadioFreq)
                     lastSetRxFreq = rxRadioFreq.toDouble()
                 }
             }
 
             _state.update {
                 it.copy(
-                        txConnected = tx?.isConnected ?: false,
+                    txConnected  = txNow?.isConnected ?: false,
-                        rxConnected = rx?.isConnected ?: false,
+                    rxConnected  = rxNow?.isConnected ?: false,
                     txFrequencyHz = txRadioFreq,
                     rxFrequencyHz = rxRadioFreq,
                     azimuth      = Math.toDegrees(pos.azimuth),
@@ -266,12 +287,196 @@ class RadioTrackingService(
                     distance     = pos.distance
                 )
             }
-
             delay(1000)
         }
     }
+
+    // ── IC-705 split-radio tracking ─────────────────────────────────────────
+
+    private suspend fun runSplitTracking(transponder: SatRadio, initialTxBaseFreqHz: Long?) {
+        val radio = txController ?: return
+        if (!radio.isConnected) return
+
+        val txMode = transponder.uplinkMode
+        val rxMode = transponder.downlinkMode
+            ?: transponder.uplinkMode?.let {
+                TransponderMapper.mapUplinkModeToDownlinkMode(it, transponder.isInverted)
             }
 
+        // Compute nominal base frequencies
+        val txCenter = when {
+            transponder.uplinkLow != null && transponder.uplinkHigh != null ->
+                (transponder.uplinkLow!! + transponder.uplinkHigh!!) / 2
+            transponder.uplinkLow != null -> transponder.uplinkLow!!
+            else -> null
+        }
+        val rxNominal = if (txCenter != null) {
+            TransponderMapper.mapUplinkToDownlink(txCenter, transponder)
+        } else transponder.downlinkLow
+
+        val txBase = initialTxBaseFreqHz ?: txCenter
+        Log.i(tag, "IC-705 split setup: txBase=${txBase}Hz rxNominal=${rxNominal}Hz txMode=$txMode rxMode=$rxMode")
+
+        // ── Initial setup sequence ──────────────────────────────────────────
+        // Sequence per IC-705: explicitly select VFO, then band → freq → mode.
+        // ACK from each command gates the next — no fixed delays needed.
+
+        // VFO-A = RX (downlink)
+        Log.d(tag, "Split init: selecting VFO-A for RX (downlink)")
+        radio.setVfo(vfoA = true)
+        if (rxNominal != null) {
+            Log.d(tag, "Split init: VFO-A band for ${rxNominal}Hz")
+            radio.setBand(rxNominal)
+            Log.d(tag, "Split init: VFO-A freq=${rxNominal}Hz")
+            radio.setFrequency(rxNominal)
+        }
+        if (rxMode != null) {
+            Log.d(tag, "Split init: VFO-A mode=$rxMode")
+            radio.setMode(rxMode)
+        }
+
+        // VFO-B = TX (uplink)
+        Log.d(tag, "Split init: selecting VFO-B for TX (uplink)")
+        radio.setVfo(vfoA = false)
+        if (txBase != null) {
+            Log.d(tag, "Split init: VFO-B band for ${txBase}Hz")
+            radio.setBand(txBase)
+            Log.d(tag, "Split init: VFO-B freq=${txBase}Hz")
+            radio.setFrequency(txBase)
+        }
+        if (txMode != null) {
+            Log.d(tag, "Split init: VFO-B mode=$txMode")
+            radio.setMode(txMode)
+        }
+        if (txMode?.uppercase() == "FM") {
+            val tone = _state.value.ctcssTone
+            if (tone != null) {
+                Log.d(tag, "Split init: CTCSS=${tone}Hz")
+                radio.setCtcssTone(tone)
+                radio.setCtcssMode(true)
+            } else {
+                radio.setCtcssMode(false)
+            }
+        }
+
+        // Enable SPLIT on VFO-A (return display to RX VFO first)
+        Log.d(tag, "Split init: returning to VFO-A, then enabling SPLIT mode")
+        radio.setVfo(vfoA = true)
+        radio.setSplitMode(enabled = true)
+
+        _state.update { it.copy(txMode = txMode, rxMode = rxMode, txBaseFrequencyHz = txBase) }
+        Log.i(tag, "IC-705 split init done — entering tracking loop")
+
+        // ── Tracking loop with tuning detection ─────────────────────────────
+        var lastSetTxFreq = 0.0
+        var lastSetRxFreq = 0.0
+        var tuningRadio   = ""  // "tx" or "rx" when manual tuning detected
+        var lastReadFreq  = 0L
+        var stableCount   = 0
+
+        while (currentCoroutineContext().isActive) {
+            val currentState = _state.value
+            if (!currentState.isActive) break
+
+            val satPass = currentState.currentPass ?: break
+            val xpdr    = currentState.selectedTransponder ?: break
+            var txBaseFreq = currentState.txBaseFrequencyHz
+            val stationPos = settingsRepo.stationPosition.value
+            val pos = satelliteRepo.getPosition(satPass.orbitalObject, stationPos, System.currentTimeMillis())
+            val v = pos.distanceRate * 1000.0
+
+            if (tuningRadio.isNotEmpty()) {
+                // User is tuning — wait for frequency to stabilize
+                val readFreq = if (tuningRadio == "tx") radio.readTxVfoFrequency() else radio.readWorkingFrequency()
+                if (readFreq != null) {
+                    if (kotlin.math.abs(readFreq - lastReadFreq) <= 20) stableCount++
+                    else { stableCount = 0; lastReadFreq = readFreq }
+
+                    if (stableCount >= 2) {
+                        // Frequency stable — reverse-calculate base frequency
+                        if (tuningRadio == "tx" && txBaseFreq != null) {
+                            val newBase = (readFreq.toDouble() * SPEED_OF_LIGHT / (SPEED_OF_LIGHT + v)).toLong()
+                            if (newBase > 0) {
+                                txBaseFreq = newBase
+                                _state.update { it.copy(txBaseFrequencyHz = newBase) }
+                                Log.i(tag, "Split TX tuning done → base=$newBase")
+                            }
+                        } else if (tuningRadio == "rx") {
+                            val rxNominal = (readFreq.toDouble() * SPEED_OF_LIGHT / (SPEED_OF_LIGHT - v)).toLong()
+                            val newTxBase = TransponderMapper.mapDownlinkToUplink(rxNominal, xpdr)
+                            if (newTxBase != null && newTxBase > 0) {
+                                txBaseFreq = newTxBase
+                                _state.update { it.copy(txBaseFrequencyHz = newTxBase) }
+                                Log.i(tag, "Split RX tuning done → txBase=$newTxBase")
+                            }
+                        }
+                        tuningRadio   = ""
+                        stableCount   = 0
+                        lastSetTxFreq = 0.0
+                        lastSetRxFreq = 0.0
+                    }
+                }
+            } else {
+                // Detect manual dial changes
+                if (txBaseFreq != null && lastSetTxFreq > 0.0) {
+                    val readTx = radio.readTxVfoFrequency()
+                    if (readTx != null && kotlin.math.abs(readTx - lastSetTxFreq) >= 20.0) {
+                        tuningRadio  = "tx"
+                        lastReadFreq = readTx
+                        stableCount  = 0
+                        Log.i(tag, "Split TX tuning detected (read=${readTx}, lastSet=$lastSetTxFreq)")
+                    }
+                }
+                if (tuningRadio.isEmpty() && lastSetRxFreq > 0.0) {
+                    val readRx = radio.readWorkingFrequency()
+                    if (readRx != null && kotlin.math.abs(readRx - lastSetRxFreq) >= 20.0) {
+                        tuningRadio  = "rx"
+                        lastReadFreq = readRx
+                        stableCount  = 0
+                        Log.i(tag, "Split RX tuning detected (read=${readRx}, lastSet=$lastSetRxFreq)")
+                    }
+                }
+            }
+
+            // Determine Doppler-corrected frequencies
+            val txRadioFreq = txBaseFreq?.let { pos.getUplinkFreq(it) }
+            val rxBaseCalc  = if (txBaseFreq != null) {
+                TransponderMapper.mapUplinkToDownlink(txBaseFreq, xpdr)
+            } else xpdr.downlinkLow
+            val rxRadioFreq = rxBaseCalc?.let { pos.getDownlinkFreq(it) }
+
+            if (radio.isConnected && tuningRadio.isEmpty()) {
+                // Update both VFOs every cycle — no PTT polling needed.
+                // 0x25/00 = active (RX) VFO, 0x25/01 = inactive (TX) VFO.
+                if (rxRadioFreq != null) {
+                    Log.d(tag, "Split loop RX (0x25/00): ${rxRadioFreq}Hz")
+                    radio.setWorkingFrequency(rxRadioFreq)
+                    lastSetRxFreq = rxRadioFreq.toDouble()
+                }
+                if (txRadioFreq != null) {
+                    Log.d(tag, "Split loop TX (0x25/01): ${txRadioFreq}Hz")
+                    radio.setTxVfoFrequency(txRadioFreq)
+                    lastSetTxFreq = txRadioFreq.toDouble()
+                }
+            }
+
+            _state.update {
+                it.copy(
+                    txConnected   = radio.isConnected,
+                    rxConnected   = false,  // single radio
+                    txFrequencyHz = txRadioFreq,
+                    rxFrequencyHz = rxRadioFreq,
+                    azimuth       = Math.toDegrees(pos.azimuth),
+                    elevation     = Math.toDegrees(pos.elevation),
+                    distance      = pos.distance
+                )
+            }
+            delay(1000)
+        }
+    }
+
+    // ── Other IRadioTrackingService methods ─────────────────────────────────
+
     override fun stopTracking() {
         trackingJob?.cancel()
         trackingJob = null
@@ -288,7 +493,6 @@ class RadioTrackingService(
                     TransponderMapper.mapUplinkModeToDownlinkMode(it, transponder.isInverted)
                 }
             rxMode?.let { rx?.setMode(it) }
-
             if (transponder.uplinkMode?.uppercase() == "FM") {
                 _state.value.ctcssTone?.let { tone ->
                     tx?.setCtcssTone(tone)
@@ -302,13 +506,9 @@ class RadioTrackingService(
             transponder.uplinkLow != null -> transponder.uplinkLow!!
             else -> null
         }
-        // Show nominal frequencies immediately
         val rxNominal = if (txCenter != null) {
             TransponderMapper.mapUplinkToDownlink(txCenter, transponder)
-        } else {
+        } else transponder.downlinkLow
-            // Downlink-only transponder (beacon etc.) - use downlink directly
-            transponder.downlinkLow
-        }
         _state.update {
             it.copy(
                 selectedTransponder = transponder,
@@ -353,5 +553,4 @@ class RadioTrackingService(
         }
         _state.update { it.copy(txMode = txMode, rxMode = rxMode) }
     }
-
 }

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

@@ -26,6 +26,7 @@ import androidx.room.Room
 import com.rtbishop.look4sat.core.data.database.Look4SatDb
 import com.rtbishop.look4sat.core.data.framework.BluetoothReporter
 import com.rtbishop.look4sat.core.data.framework.Ft817Controller
+import com.rtbishop.look4sat.core.data.framework.Ic705Controller
 import com.rtbishop.look4sat.core.data.framework.NetworkReporter
 import com.rtbishop.look4sat.core.data.framework.RadioTrackingService
 import com.rtbishop.look4sat.core.data.repository.DatabaseRepo
@@ -39,6 +40,7 @@ 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.model.RadioControlSettings
 import com.rtbishop.look4sat.core.domain.repository.IDatabaseRepo
 import com.rtbishop.look4sat.core.domain.repository.IMainContainer
 import com.rtbishop.look4sat.core.domain.repository.IRadioController
@@ -107,14 +109,24 @@ class MainContainer(private val context: Context) : IMainContainer {
 
     override fun provideTxRadioController(): IRadioController {
         val manager  = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
-        val address = settingsRepo.radioControlSettings.value.txRadioAddress
+        val settings = settingsRepo.radioControlSettings.value
-        return Ft817Controller(manager, address)
+        val address  = settings.txRadioAddress
+        return if (settings.radioModel == RadioControlSettings.MODEL_ICOM_IC705) {
+            Ic705Controller(manager, address)
+        } else {
+            Ft817Controller(manager, address)
+        }
     }
 
     override fun provideRxRadioController(): IRadioController {
         val manager  = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
-        val address = settingsRepo.radioControlSettings.value.rxRadioAddress
+        val settings = settingsRepo.radioControlSettings.value
-        return Ft817Controller(manager, address)
+        val address  = settings.rxRadioAddress
+        return if (settings.radioModel == RadioControlSettings.MODEL_ICOM_IC705) {
+            Ic705Controller(manager, address)
+        } else {
+            Ft817Controller(manager, address)
+        }
     }
 
     override fun provideSensorsRepo(): ISensorsRepo {

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

@@ -383,6 +383,7 @@ class SettingsRepo(
     private val keyTxRadioName = "txRadioName"
     private val keyRxRadioName = "rxRadioName"
     private val keyRadioBaudRate = "radioBaudRate"
+    private val keyRadioSplitMode = "radioSplitMode"
 
     private val _radioControlSettings = MutableStateFlow(getRadioControlSettings())
     override val radioControlSettings: StateFlow<RadioControlSettings> = _radioControlSettings
@@ -396,18 +397,20 @@ class SettingsRepo(
             putString(keyTxRadioName, settings.txRadioName)
             putString(keyRxRadioName, settings.rxRadioName)
             putInt(keyRadioBaudRate, settings.baudRate)
+            putBoolean(keyRadioSplitMode, settings.splitMode)
         }
         _radioControlSettings.value = settings
     }
 
     private fun getRadioControlSettings(): RadioControlSettings = RadioControlSettings(
         enabled = preferences.getBoolean(keyRadioControlEnabled, false),
-        radioModel = preferences.getString(keyRadioModel, null) ?: "Yaesu FT-817/818",
+        radioModel = preferences.getString(keyRadioModel, null) ?: RadioControlSettings.MODEL_YAESU_FT817,
         txRadioAddress = preferences.getString(keyTxRadioAddress, null) ?: "",
         rxRadioAddress = preferences.getString(keyRxRadioAddress, null) ?: "",
         txRadioName = preferences.getString(keyTxRadioName, null) ?: "TX Radio",
         rxRadioName = preferences.getString(keyRxRadioName, null) ?: "RX Radio",
-        baudRate = preferences.getInt(keyRadioBaudRate, 4800)
+        baudRate = preferences.getInt(keyRadioBaudRate, 4800),
+        splitMode = preferences.getBoolean(keyRadioSplitMode, false)
     )
     //endregion
 }

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

@@ -74,12 +74,20 @@ data class RadioControlSettings(
     val rxRadioAddress: String,
     val txRadioName: String,
     val rxRadioName: String,
-    val baudRate: Int
+    val baudRate: Int,
+    /** IC-705 only: use single-radio split-VFO mode instead of two radios. */
+    val splitMode: Boolean = false
 ) {
     companion object {
-        val SUPPORTED_RADIOS = listOf(
+        const val MODEL_YAESU_FT817   = "Yaesu FT-817/818"
-            "Yaesu FT-817/818",
+        const val MODEL_YAESU_FT857   = "Yaesu FT-857/897"
-            "Yaesu FT-857/897"
+        const val MODEL_ICOM_IC705    = "Icom IC-705"
-        )
+
+        val SUPPORTED_RADIOS = listOf(MODEL_YAESU_FT817, MODEL_YAESU_FT857, MODEL_ICOM_IC705)
+
+        /** Baud rates available for Yaesu radios. */
+        val BAUD_RATES_YAESU = listOf(4800, 9600, 38400)
+        /** Baud rates available for Icom IC-705 (higher speeds supported via CI-V USB/BT). */
+        val BAUD_RATES_ICOM  = listOf(4800, 9600, 19200, 38400, 57600, 115200)
     }
 }

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

@@ -38,4 +38,51 @@ interface IRadioController {
     suspend fun pttOn(): Boolean
 
     suspend fun pttOff(): Boolean
+
+    // ── Extended operations (IC-705 / CI-V) ──────────────────────────────
+
+    /**
+     * Select the band matching [frequencyHz] via the band stacking register.
+     * Must be called before [setFrequency] and [setMode] when first tracking.
+     * Default: no-op (Yaesu radios auto-switch band via frequency).
+     */
+    suspend fun setBand(frequencyHz: Long): Boolean = false
+
+    /**
+     * Select the active VFO.
+     * @param vfoA true → VFO-A (main/RX), false → VFO-B (sub/TX in split).
+     */
+    suspend fun setVfo(vfoA: Boolean): Boolean = false
+
+    /**
+     * Enable or disable SPLIT mode (TX on sub-VFO, RX on main VFO).
+     * Default: not supported.
+     */
+    suspend fun setSplitMode(enabled: Boolean): Boolean = false
+
+    /**
+     * Set the frequency of the currently active VFO (IC-705: CMD 0x25 sub 0x00).
+     * Default: delegates to [setFrequency].
+     */
+    suspend fun setWorkingFrequency(frequencyHz: Long): Boolean = setFrequency(frequencyHz)
+
+    /**
+     * Set the frequency of the inactive/TX VFO (IC-705: CMD 0x25 sub 0x01).
+     * Sent every tracking cycle alongside [setWorkingFrequency] in split mode.
+     * Default: delegates to [setWorkingFrequency].
+     */
+    suspend fun setTxVfoFrequency(frequencyHz: Long): Boolean = setWorkingFrequency(frequencyHz)
+
+    /**
+     * Read the frequency of the currently active VFO (IC-705: CMD 0x25 sub 0x00).
+     * Default: delegates to [readFrequencyAndMode].
+     */
+    suspend fun readWorkingFrequency(): Long? = readFrequencyAndMode()?.first
+
+    /**
+     * Read the frequency of the inactive/TX VFO (IC-705: CMD 0x25 sub 0x01).
+     * Used for tuning detection in split mode.
+     * Default: delegates to [readWorkingFrequency].
+     */
+    suspend fun readTxVfoFrequency(): Long? = readWorkingFrequency()
 }

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsDialog.kt

@@ -22,11 +22,14 @@ import android.content.Context
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 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.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.FilterChip
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
@@ -38,6 +41,7 @@ import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
@@ -438,6 +442,7 @@ private fun OutputChannelSection(
     }
 }
 
+@OptIn(ExperimentalLayoutApi::class)
 @Composable
 fun RadioControlDialog(
     initialSettings: RadioControlSettings,
@@ -446,9 +451,9 @@ fun RadioControlDialog(
 ) {
     val context    = androidx.compose.ui.platform.LocalContext.current
     val padding    = LocalSpacing.current.large
-    val baudRates = listOf(4800, 9600, 38400)
     val enabled    = rememberSaveable { mutableStateOf(initialSettings.enabled) }
     val radioModel = rememberSaveable { mutableStateOf(initialSettings.radioModel) }
+    val splitMode  = rememberSaveable { mutableStateOf(initialSettings.splitMode) }
     val txAddress  = rememberSaveable { mutableStateOf(initialSettings.txRadioAddress) }
     val rxAddress  = rememberSaveable { mutableStateOf(initialSettings.rxRadioAddress) }
     val txName     = rememberSaveable { mutableStateOf(initialSettings.txRadioName) }
@@ -456,12 +461,26 @@ fun RadioControlDialog(
     val baudRate   = rememberSaveable { mutableIntStateOf(initialSettings.baudRate) }
     val selectingFor = rememberSaveable { mutableStateOf("") } // "tx", "rx", or ""
 
-    val pairedDevices = remember {
+    val isIcom = radioModel.value == RadioControlSettings.MODEL_ICOM_IC705
+    val isSingleRadio = isIcom && splitMode.value
+
+    // Reset split mode when switching away from IC-705
+    if (!isIcom && splitMode.value) splitMode.value = false
+
+    val baudRates = if (isIcom) RadioControlSettings.BAUD_RATES_ICOM
+                   else         RadioControlSettings.BAUD_RATES_YAESU
+
+    // If current baud rate is not in the new list, default to the first available
+    if (baudRate.intValue !in baudRates) baudRate.intValue = baudRates.first()
+
+    val pairedDevices: List<Pair<String, String>> = remember {
+        buildList {
             try {
                 val manager = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
-            manager.adapter?.bondedDevices?.map { Pair(it.name ?: "Unknown", it.address) } ?: emptyList()
+                manager.adapter?.bondedDevices?.forEach {
-        } catch (_: SecurityException) {
+                    add(Pair(it.name ?: "Unknown", it.address ?: ""))
-            emptyList()
+                }
+            } catch (_: SecurityException) { }
         }
     }
 
@@ -471,20 +490,24 @@ fun RadioControlDialog(
                 enabled        = enabled.value,
                 radioModel     = radioModel.value,
                 txRadioAddress = txAddress.value,
-                rxRadioAddress = rxAddress.value,
+                rxRadioAddress = if (isSingleRadio) "" else rxAddress.value,
                 txRadioName    = txName.value,
-                rxRadioName = rxName.value,
+                rxRadioName    = if (isSingleRadio) "" else rxName.value,
-                baudRate = baudRate.intValue
+                baudRate       = baudRate.intValue,
+                splitMode      = splitMode.value
             )
         )
         onDismiss()
     }
+
     SharedDialog(
         title    = stringResource(R.string.rc_settings_title),
         onCancel = onDismiss,
         onAccept = onAccept
     ) {
         Column(modifier = Modifier.padding(horizontal = padding)) {
+
+            // Enable switch
             Row(
                 horizontalArrangement = Arrangement.SpaceBetween,
                 verticalAlignment     = Alignment.CenterVertically,
@@ -495,15 +518,15 @@ fun RadioControlDialog(
             }
             Spacer(modifier = Modifier.height(6.dp))
 
-            // Radio model selection
+            // Radio model — FlowRow so chips wrap on small screens
             Text(
-                stringResource(R.string.rc_radio_model),
+                text       = stringResource(R.string.rc_radio_model),
-                fontWeight = androidx.compose.ui.text.font.FontWeight.Medium,
+                fontWeight = FontWeight.Medium,
                 color      = androidx.compose.material3.MaterialTheme.colorScheme.primary
             )
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
+            FlowRow(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
                 RadioControlSettings.SUPPORTED_RADIOS.forEach { model ->
-                    androidx.compose.material3.FilterChip(
+                    FilterChip(
                         selected = radioModel.value == model,
                         onClick  = { radioModel.value = model },
                         label    = { Text(model, fontSize = 12.sp) },
@@ -513,39 +536,70 @@ fun RadioControlDialog(
             }
             Spacer(modifier = Modifier.height(6.dp))
 
-            // TX Radio selection
+            // IC-705 split-mode toggle (only shown for IC-705)
-            Text("TX Radio (Uplink)", fontWeight = androidx.compose.ui.text.font.FontWeight.Medium)
+            if (isIcom) {
+                Row(
+                    horizontalArrangement = Arrangement.SpaceBetween,
+                    verticalAlignment     = Alignment.CenterVertically,
+                    modifier              = Modifier.fillMaxWidth()
+                ) {
+                    Column(modifier = Modifier.weight(1f)) {
+                        Text("Split mode (single radio)", fontWeight = FontWeight.Medium)
+                        Text(
+                            text     = "Use VFO-A/B split on one IC-705 instead of two radios",
+                            fontSize = 12.sp,
+                            color    = androidx.compose.material3.MaterialTheme.colorScheme.onSurfaceVariant
+                        )
+                    }
+                    Switch(
+                        checked         = splitMode.value,
+                        onCheckedChange = { splitMode.value = it },
+                        enabled         = enabled.value
+                    )
+                }
+                Spacer(modifier = Modifier.height(6.dp))
+            }
+
+            // TX Radio (always shown; in split mode this is the single IC-705)
+            val txLabel = if (isSingleRadio) "Radio (IC-705)" else "TX Radio (Uplink)"
+            Text(txLabel, fontWeight = FontWeight.Medium)
             if (txAddress.value.isNotBlank()) {
-                Text("${txName.value} - ${txAddress.value}", fontSize = 13.sp)
+                Text("${txName.value} — ${txAddress.value}", fontSize = 13.sp)
             }
             CardButton(
                 onClick  = { selectingFor.value = "tx" },
-                text = "Select TX Device",
+                text     = if (isSingleRadio) "Select Device" else "Select TX Device",
                 modifier = Modifier.fillMaxWidth()
             )
             Spacer(modifier = Modifier.height(6.dp))
 
-            // RX Radio selection
+            // RX Radio (hidden in split mode — the same radio handles both)
-            Text("RX Radio (Downlink)", fontWeight = androidx.compose.ui.text.font.FontWeight.Medium)
+            if (!isSingleRadio) {
+                Text("RX Radio (Downlink)", fontWeight = FontWeight.Medium)
                 if (rxAddress.value.isNotBlank()) {
-                Text("${rxName.value} - ${rxAddress.value}", fontSize = 13.sp)
+                    Text("${rxName.value} — ${rxAddress.value}", fontSize = 13.sp)
                 }
                 CardButton(
                     onClick  = { selectingFor.value = "rx" },
                     text     = "Select RX Device",
                     modifier = Modifier.fillMaxWidth()
                 )
-
-            // Paired devices list (shown when selecting)
-            if (selectingFor.value.isNotBlank()) {
                 Spacer(modifier = Modifier.height(6.dp))
+            }
+
+            // Paired device picker (inline, shown while selecting)
+            if (selectingFor.value.isNotBlank()) {
                 Text(
                     text       = "Paired Bluetooth Devices:",
-                    fontWeight = androidx.compose.ui.text.font.FontWeight.Medium,
+                    fontWeight = FontWeight.Medium,
                     color      = androidx.compose.material3.MaterialTheme.colorScheme.primary
                 )
+                Spacer(modifier = Modifier.height(2.dp))
                 if (pairedDevices.isEmpty()) {
-                    Text("No paired devices found. Pair your BT adapter in Android Bluetooth settings first.")
+                    Text(
+                        "No paired devices found. Pair your BT adapter in Android Bluetooth settings first.",
+                        fontSize = 13.sp
+                    )
                 } else {
                     pairedDevices.forEach { (name, address) ->
                         androidx.compose.material3.Surface(
@@ -573,25 +627,21 @@ fun RadioControlDialog(
                         }
                     }
                 }
+                Spacer(modifier = Modifier.height(6.dp))
             }
 
-            Spacer(modifier = Modifier.height(6.dp))
+            // Baud rate — FlowRow so all chips fit on narrow screens
-            Row(
+            Text("Baud Rate:", fontWeight = FontWeight.Medium)
-                horizontalArrangement = Arrangement.SpaceBetween,
+            FlowRow(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                verticalAlignment = Alignment.CenterVertically,
-                modifier = Modifier.fillMaxWidth()
-            ) {
-                Text("Baud Rate:")
-                Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
                 baudRates.forEach { rate ->
-                        CardButton(
+                    FilterChip(
+                        selected = rate == baudRate.intValue,
                         onClick  = { baudRate.intValue = rate },
-                            text = if (rate == baudRate.intValue) "[$rate]" else rate.toString(),
+                        label    = { Text(rate.toString(), fontSize = 12.sp) },
-                            modifier = Modifier
+                        enabled  = enabled.value
                     )
                 }
             }
         }
     }
 }
-}