gps related minor fixes

pi/backend/gps_service.py

@@ -11,7 +11,7 @@ from typing import Any
 # When True: skips gpsd entirely, generates realistic mock data
 # When False: connects to real gpsd (requires GPS device)
 # ============================================================================
-_GPS_DEBUG = True
+_GPS_DEBUG = False
 
 # gpsdclient is a modern, simple gpsd client
 # Install gpsd on Pi: sudo apt install gpsd gpsd-clients
@@ -45,6 +45,7 @@ class GPSService:
 
         # Periodic status logging
         self._last_status_log = 0.0
+        self._last_state_emit = 0.0
         self._fix_count = 0
 
     def set_on_data(self, callback):
@@ -165,11 +166,20 @@ class GPSService:
                         timeout_s = "120s" if not self._has_ever_fixed else "10s"
                         print(f"[GPS] No GPS fix after {timeout_s}, will retry connection")
                         raise ConnectionError("No GPS fix within timeout")
+                    # Emit state periodically so UI knows we're alive
+                    now = time.time()
+                    if now - self._last_state_emit >= 5.0:
+                        self._last_state_emit = now
+                        with self._lock:
+                            self._latest = fix
+                        if self._on_data_callback:
+                            self._on_data_callback(fix)
                     continue  # Skip empty fixes
 
                 # Got real data — mark first fix, reset timeout to shorter window
                 if not self._has_ever_fixed:
                     self._has_ever_fixed = True
+                    self._last_state_emit = 0.0  # Force immediate emit on transition
                     print("[GPS] First fix acquired")
                 fix_timeout = time.time() + 10.0  # 10s timeout for signal loss
 
@@ -212,8 +222,8 @@ class GPSService:
         signal_lost = False
         signal_lost_until = 0.0
 
-        # Simulate cold start acquisition (~3s)
-        acquiring_until = time.time() + 3.0
+        # Simulate cold start acquisition (~30s)
+        acquiring_until = time.time() + 30.0
 
         # Base position (Tokyo area)
         base_lat = 35.6762

pi/backend/lte_service.py

@@ -0,0 +1,178 @@
+"""LTE service - polls ModemManager for signal quality and connection state."""
+
+import random
+import subprocess
+import re
+import threading
+import time
+from typing import Any
+
+# ============================================================================
+# DEBUG MODE - Set True for development without modem hardware
+# When True: skips mmcli entirely, generates mock LTE data
+# When False: polls real ModemManager via mmcli
+# ============================================================================
+_LTE_DEBUG = True
+
+
+class LteService:
+    """Threaded LTE modem status poller.
+
+    Polls `mmcli -m 0` every 5 seconds, parses signal quality, connection
+    state, operator, and access technology. Emits dict via callback.
+
+    No history buffer — historical signal strength isn't useful.
+    """
+
+    def __init__(self, poll_interval: float = 5.0):
+        self.poll_interval = poll_interval
+
+        self._latest: dict[str, Any] = {}
+        self._connected = False  # True when mmcli responds (modem alive)
+        self._running = False
+        self._thread: threading.Thread | None = None
+        self._lock = threading.Lock()
+
+        # Callback for push-based updates
+        self._on_data_callback = None
+
+    def set_on_data(self, callback):
+        """Set callback for new LTE data. Called with data dict."""
+        self._on_data_callback = callback
+
+    @property
+    def connected(self) -> bool:
+        """Whether the modem is reachable via mmcli."""
+        return self._connected
+
+    def get_latest(self) -> dict[str, Any]:
+        """Get most recent LTE status."""
+        with self._lock:
+            return self._latest.copy() if self._latest else {"error": "no data"}
+
+    def start(self):
+        """Start background LTE poller thread."""
+        if self._running:
+            return
+        self._running = True
+        self._thread = threading.Thread(target=self._poll_loop, daemon=True)
+        self._thread.start()
+        print("[LTE] Service started")
+
+    def stop(self):
+        """Stop background poller."""
+        self._running = False
+        if self._thread:
+            self._thread.join(timeout=2.0)
+
+    def _poll_loop(self):
+        """Main poll loop."""
+        print("[LTE] Poller thread running")
+        while self._running:
+            try:
+                if _LTE_DEBUG:
+                    data = self._stub_poll()
+                else:
+                    data = self._real_poll()
+
+                with self._lock:
+                    self._latest = data
+
+                if self._on_data_callback:
+                    self._on_data_callback(data)
+
+            except Exception as e:
+                print(f"[LTE] Poll error: {e}")
+                self._connected = False
+
+            time.sleep(self.poll_interval)
+
+    def _real_poll(self) -> dict[str, Any]:
+        """Poll mmcli -m 0 and parse output."""
+        try:
+            result = subprocess.run(
+                ["mmcli", "-m", "0"],
+                capture_output=True,
+                text=True,
+                timeout=5.0,
+            )
+
+            if result.returncode != 0:
+                self._connected = False
+                return {
+                    "connected": False,
+                    "signal": 0,
+                    "operator": None,
+                    "access_tech": None,
+                }
+
+            output = result.stdout
+            self._connected = True
+
+            # Parse signal quality: "signal quality: 68 (recent)"
+            signal = 0
+            m = re.search(r"signal quality:\s*(\d+)", output)
+            if m:
+                signal = int(m.group(1))
+
+            # Parse state: "state: connected" / "registered" / "searching" etc.
+            state = None
+            m = re.search(r"^\s*state:\s*(\S+)", output, re.MULTILINE)
+            if m:
+                state = m.group(1).strip("'\"")
+
+            # Parse operator: "operator name: KDDI KDDI"
+            operator = None
+            m = re.search(r"operator name:\s*(.+)", output)
+            if m:
+                operator = m.group(1).strip()
+
+            # Parse access tech: "access tech: lte"
+            access_tech = None
+            m = re.search(r"access tech:\s*(\S+)", output)
+            if m:
+                access_tech = m.group(1).strip("'\"")
+
+            network_connected = state in ("connected", "registered")
+
+            return {
+                "connected": network_connected,
+                "signal": signal,
+                "operator": operator,
+                "access_tech": access_tech,
+            }
+
+        except subprocess.TimeoutExpired:
+            print("[LTE] mmcli timed out")
+            self._connected = False
+            return {
+                "connected": False,
+                "signal": 0,
+                "operator": None,
+                "access_tech": None,
+            }
+        except FileNotFoundError:
+            print("[LTE] mmcli not found, falling back to stub mode")
+            self._connected = False
+            return self._stub_poll()
+
+    # Stub state lives across polls
+    _stub_signal: float = 70.0
+
+    def _stub_poll(self) -> dict[str, Any]:
+        """Generate mock LTE data for development.
+
+        Simulates connected state with signal wandering 60-80.
+        """
+        self._connected = True
+
+        # Random walk signal, clamped to 60-80
+        self._stub_signal += random.uniform(-3, 3)
+        self._stub_signal = max(60, min(80, self._stub_signal))
+
+        return {
+            "connected": True,
+            "signal": int(self._stub_signal),
+            "operator": "STUB",
+            "access_tech": "lte",
+        }

pi/backend/main.py

@@ -9,6 +9,7 @@ from flask_socketio import SocketIO, emit
 from gps_service import GPSService
 from arduino_service import ArduinoService
 from gpio_service import GPIOService
+from lte_service import LteService
 from throttle import Throttle
 
 app = Flask(__name__)
@@ -21,10 +22,12 @@ socketio = SocketIO(app, async_mode="gevent", cors_allowed_origins="*")
 gps = GPSService()
 arduino = ArduinoService()
 gpio = GPIOService()
+lte = LteService()
 
-# Throttles for emission rate limiting (20Hz for arduino, 1Hz for GPS)
+# Throttles for emission rate limiting (20Hz for arduino, 1Hz for GPS, 5s for LTE)
 arduino_throttle = Throttle(min_interval=0.05)  # 20Hz max
 gps_throttle = Throttle(min_interval=1.0)      # 1Hz max
+lte_throttle = Throttle(min_interval=5.0)      # Every 5s — signal doesn't need real-time
 
 # Track connected clients
 connected_clients = set()
@@ -57,6 +60,10 @@ def handle_connect():
     if "error" not in gps_data:
         emit("gps", gps_data)
 
+    lte_data = lte.get_latest()
+    if "error" not in lte_data:
+        emit("lte", lte_data)
+
 
 @socketio.on("disconnect")
 def handle_disconnect():
@@ -133,6 +140,10 @@ def on_arduino_data(data):
     data = dict(data)  # Don't mutate original
     data["theme_switch"] = gpio.theme_switch
     
+    # backend voltage offset correction
+    if "voltage" in data:
+        data["voltage"] += 0.2  # Calibration offset
+
     def emit_fn(d):
         socketio.emit("arduino", d)
 
@@ -147,6 +158,14 @@ def on_gps_data(data):
     gps_throttle.maybe_emit(data, emit_fn)
 
 
+def on_lte_data(data):
+    """Called by LteService when new status polled."""
+    def emit_fn(d):
+        socketio.emit("lte", d)
+
+    lte_throttle.maybe_emit(data, emit_fn)
+
+
 def on_arduino_ack(cmd, status, extra):
     """Called by ArduinoService when ACK received from Arduino."""
     socketio.emit("ack", {
@@ -172,6 +191,9 @@ def throttle_flusher():
         if gps_throttle.has_pending:
             gps_throttle.flush(lambda d: socketio.emit("gps", d))
 
+        if lte_throttle.has_pending:
+            lte_throttle.flush(lambda d: socketio.emit("lte", d))
+
 
 # -----------------------------------------------------------------------------
 # REST API (backward compatibility)
@@ -181,11 +203,14 @@ def throttle_flusher():
 def health():
     """Health check endpoint."""
     gps_latest = gps.get_latest()
+    lte_latest = lte.get_latest()
     return jsonify({
         "status": "ok",
         "gps_connected": gps.connected,
         "gps_state": gps_latest.get("gps_state", "acquiring"),
         "arduino_connected": arduino.connected,
+        "lte_connected": lte.connected,
+        "lte_signal": lte_latest.get("signal"),
         "ws_clients": len(connected_clients),
     })
 
@@ -202,6 +227,12 @@ def gps_history():
     return jsonify(gps.get_buffer())
 
 
+@app.route("/lte")
+def lte_data():
+    """Current LTE modem status."""
+    return jsonify(lte.get_latest())
+
+
 @app.route("/arduino")
 def arduino_data():
     """Current Arduino telemetry (voltage, rpm, etc)."""
@@ -224,11 +255,13 @@ def main():
     arduino.set_on_data(on_arduino_data)
     arduino.set_on_ack(on_arduino_ack)
     gps.set_on_data(on_gps_data)
+    lte.set_on_data(on_lte_data)
 
     # Start services
     gps.start()
     arduino.start()
     gpio.start()
+    lte.start()
 
     # Start throttle flusher in background
     socketio.start_background_task(throttle_flusher)
@@ -241,6 +274,7 @@ def main():
         arduino.stop()
         gps.stop()
         gpio.stop()
+        lte.stop()
 
 
 if __name__ == "__main__":

pi/ui/lib/screens/dashboard_screen.dart

@@ -37,6 +37,7 @@ class _DashboardScreenState extends State<DashboardScreen> {
   // WebSocket stream subscriptions
   StreamSubscription<ArduinoData>? _arduinoSub;
   StreamSubscription<GpsData>? _gpsSub;
+  StreamSubscription<LteData>? _lteSub;
   StreamSubscription<WsConnectionState>? _connectionSub;
 
   // Pi temperature - direct file read (safety critical)
@@ -114,6 +115,13 @@ class _DashboardScreenState extends State<DashboardScreen> {
       });
     });
 
+    // Subscribe to LTE data stream
+    _lteSub = WebSocketService.instance.lteStream.listen((data) {
+      setState(() {
+        _lteSignal = data.signal;
+      });
+    });
+
     // Subscribe to connection state
     _connectionSub = WebSocketService.instance.connectionStream.listen((state) {
       setState(() {
@@ -151,8 +159,11 @@ class _DashboardScreenState extends State<DashboardScreen> {
 
     _wsState = WebSocketService.instance.connectionState;
 
-    // Placeholder: LTE signal (TODO: wire up when LTE service exists)
-    _lteSignal = null;
+    // Init from cached LTE data
+    final cachedLte = WebSocketService.instance.latestLte;
+    if (cachedLte != null) {
+      _lteSignal = cachedLte.signal;
+    }
 
     // DEBUG: flip-flop theme + navigator every 2s
     TestFlipFlopService.instance.start(navigatorKey: _navigatorKey);
@@ -163,6 +174,7 @@ class _DashboardScreenState extends State<DashboardScreen> {
     _piTempTimer?.cancel();
     _arduinoSub?.cancel();
     _gpsSub?.cancel();
+    _lteSub?.cancel();
     _connectionSub?.cancel();
     TestFlipFlopService.instance.stop();
     super.dispose();

pi/ui/lib/services/backend_service.dart

@@ -58,6 +58,25 @@ class GpsData {
   }
 }
 
+/// Data from LTE modem (signal quality, connection state)
+class LteData {
+  final bool? connected;
+  final int? signal; // 0-100 percent
+  final String? operator_;
+  final String? accessTech;
+
+  LteData({this.connected, this.signal, this.operator_, this.accessTech});
+
+  factory LteData.fromJson(Map<String, dynamic> json) {
+    return LteData(
+      connected: json['connected'] as bool?,
+      signal: (json['signal'] as num?)?.toInt(),
+      operator_: json['operator'] as String?,
+      accessTech: json['access_tech'] as String?,
+    );
+  }
+}
+
 /// HTTP client for Flask backend - fire-and-forget async fetch, sync cache return
 ///
 /// Follows the same pattern as PiIO: never blocks UI, always returns cached data.

pi/ui/lib/services/websocket_service.dart

@@ -65,11 +65,13 @@ class WebSocketService {
   // Latest values for sync access (backward compat)
   ArduinoData? _latestArduino;
   GpsData? _latestGps;
+  LteData? _latestLte;
   BackendStatus? _latestStatus;
 
   // Stream controllers
   late StreamController<ArduinoData> _arduinoController;
   late StreamController<GpsData> _gpsController;
+  late StreamController<LteData> _lteController;
   late StreamController<BackendStatus> _statusController;
   late StreamController<CommandAck> _ackController;
   late StreamController<BackendAlert> _alertController;
@@ -83,6 +85,7 @@ class WebSocketService {
   void _setupStreams() {
     _arduinoController = StreamController<ArduinoData>.broadcast();
     _gpsController = StreamController<GpsData>.broadcast();
+    _lteController = StreamController<LteData>.broadcast();
     _statusController = StreamController<BackendStatus>.broadcast();
     _ackController = StreamController<CommandAck>.broadcast();
     _alertController = StreamController<BackendAlert>.broadcast();
@@ -107,6 +110,9 @@ class WebSocketService {
   /// Stream of GPS updates
   Stream<GpsData> get gpsStream => _gpsController.stream;
 
+  /// Stream of LTE status updates
+  Stream<LteData> get lteStream => _lteController.stream;
+
   /// Stream of backend status updates
   Stream<BackendStatus> get statusStream => _statusController.stream;
 
@@ -139,6 +145,9 @@ class WebSocketService {
   /// Latest GPS data (may be null if not yet received)
   GpsData? get latestGps => _latestGps;
 
+  /// Latest LTE data (may be null if not yet received)
+  LteData? get latestLte => _latestLte;
+
   /// Latest backend status
   BackendStatus? get latestStatus => _latestStatus;
 
@@ -208,6 +217,15 @@ class WebSocketService {
       }
     });
 
+    _socket!.on('lte', (data) {
+      if (data is Map<String, dynamic>) {
+        final lte = LteData.fromJson(data);
+        _latestLte = lte;
+        _lteController.add(lte);
+        _log('lte: ${lte.signal ?? "-"}% ${lte.operator_ ?? "-"} ${lte.accessTech ?? "-"}');
+      }
+    });
+
     _socket!.on('status', (data) {
       if (data is Map<String, dynamic>) {
         final status = BackendStatus(
@@ -323,6 +341,7 @@ class WebSocketService {
     disconnect();
     _arduinoController.close();
     _gpsController.close();
+    _lteController.close();
     _statusController.close();
     _ackController.close();
     _alertController.close();

pi/ui/lib/widgets/gps_compass.dart

@@ -61,7 +61,7 @@ class GpsCompass extends StatelessWidget {
               _hasSignal ? "${_displayHeading} ${_compassDirection}" : (_isAcquiring ? "ACQ" : "N/A"),
               style: TextStyle(
                 fontSize: 80,
-                color: theme.subdued,
+                color: theme.subdued, // less emphasis on text, let the icon have semantic colour
                 fontFamily: 'DIN1451',
               ),
             ),

pi/ui/lib/widgets/system_bar.dart

@@ -70,7 +70,7 @@ class SystemBar extends StatelessWidget {
                   value: gpsState == 'acquiring' ? 'ACQ'
                        : gpsState == 'fix' ? (gpsSatellites?.toString() ?? 'N/A')
                        : '0',  // lost or unknown
-                  isAbnormal: gpsState != 'fix',
+                  isAbnormal: gpsState != 'fix' || gpsSatellites == null,
                   alignment: Alignment.centerLeft,
                   labelSize: labelSize,
                   valueSize: valueSize,