feat(sdr): local receivers — browser RTL-SDR, Local ADS-B layer and decoder feeds (#732)

Adds a Local ADS-B layer fed by your own receivers: a browser WebUSB
RTL-SDR (with FM listening) and local 1090/978 MHz decoder feeds
(LOCAL_RECEIVER_FEEDS, local and private addresses only). Local aircraft
draw in magenta with class, silhouettes, 3D models, trails and a position
sanity filter; the click card names the band and input that heard them.

Builds on Sameh Khamis's SDR prototype and the initial GEV port by
Mazeyar Moeini Feizabadi (#134); the decoder-feed design follows the
notes on #57. Closes #57.

Co-authored-by: Sameh Khamis <[email protected]>
Co-authored-by: Mazeyar Moeini Feizabadi <[email protected]>

src/ui/localSdrPresentation.js

@@ -0,0 +1,146 @@
+import { localReceiverFeedName } from '../layers/localAdsb/feedNames.js';
+
+/**
+ * Pure presentation of the Local RTL-SDR card in the Radio panel. Receives the
+ * receiver session snapshot and returns what each control should show.
+ */
+
+function formatGain(gain) {
+  return gain === 'auto' || !Number.isFinite(gain) ? 'auto' : gain.toFixed(1);
+}
+
+function formatIq(state) {
+  return Number.isFinite(state.iqLevelDbfs)
+    ? `${state.iqLevelDbfs.toFixed(1)} dBFS`
+    : '--';
+}
+
+function statusText(state) {
+  const fmActive = state.mode === 'fm';
+  const iqStatus =
+    state.samplesPerSecond > 0
+      ? `${(state.samplesPerSecond / 1_000_000).toFixed(2)} MS/s IQ`
+      : 'waiting for IQ';
+  const device = state.deviceLabel ? ` · ${state.deviceLabel}` : '';
+  if (state.connected && !fmActive) {
+    return `${state.message}${device} · ${iqStatus} · ${state.decodedMessages} messages`;
+  }
+  const detail = state.seeking
+    ? state.seekMessage
+    : state.seekMessage || state.message;
+  if (state.connected && fmActive) {
+    const workerStatus =
+      state.workerBlocks > 0
+        ? `DSP ${state.workerBlocks} blocks`
+        : 'DSP waiting';
+    const rfStatus = `RF ${formatIq(state)}`;
+    const audioSignal = Number.isFinite(state.audioLevelDbfs)
+      ? `${state.audioLevelDbfs.toFixed(1)} dBFS audio`
+      : 'audio signal --';
+    return `${detail}${device} · ${iqStatus} · ${workerStatus} · ${rfStatus} · ${audioSignal} · audio ${state.audioState}`;
+  }
+  return detail;
+}
+
+/**
+ * Derive the card's control states from one receiver snapshot.
+ * @param {object} state SdrController.getState() snapshot.
+ * @returns {object} Control presentation.
+ */
+export function localSdrCardView(state) {
+  const transitional =
+    state.status === 'connecting' || state.status === 'tuning';
+  const fmActive = state.mode === 'fm';
+  const adsbActive = state.mode === 'adsb';
+  const fmInteractive =
+    state.connected && fmActive && state.status === 'streaming';
+  return {
+    connectionLabel: state.connected
+      ? adsbActive
+        ? `${state.aircraftHeard || 0} HEARD`
+        : 'STREAMING'
+      : String(state.status || 'idle').toUpperCase(),
+    connectionActive: Boolean(state.connected),
+    connectLabel: transitional
+      ? String(state.status).toUpperCase()
+      : state.connected
+        ? 'DISCONNECT'
+        : 'CONNECT',
+    connectDisabled: transitional || !state.webUsbSupported,
+    connectPressed: Boolean(state.connected),
+    fmActive,
+    adsbActive,
+    modeDisabled: transitional,
+    locateLabel:
+      state.locationStatus === 'requesting'
+        ? 'LOCATING…'
+        : state.locationStatus === 'ready'
+          ? 'LOCATED'
+          : 'LOCATE',
+    locateDisabled: state.locationStatus === 'requesting',
+    locateActive: state.locationStatus === 'ready',
+    changeDeviceDisabled: transitional || !state.webUsbSupported,
+    gainValue: formatGain(state.gain),
+    gainDisabled: transitional,
+    statsHidden: !(adsbActive && state.connected),
+    stats: {
+      rate: Number.isFinite(state.messagesPerSecond)
+        ? state.messagesPerSecond.toFixed(1)
+        : '--',
+      heard: String(state.aircraftHeard || 0),
+      positioned: String(state.aircraftPositioned || 0),
+      iq: formatIq(state),
+    },
+    frequencyDisabled: !fmActive || transitional,
+    frequencyValue: fmActive
+      ? (state.frequencyHz / 1_000_000).toFixed(1)
+      : null,
+    tuneDisabled: !state.connected || !fmActive || transitional,
+    seekDisabled: !fmInteractive || Boolean(state.seeking),
+    volumePercent: Math.round((Number(state.volume) || 0) * 100),
+    volumeDisabled: !fmActive,
+    statusText: statusText(state),
+    statusError: state.status === 'error' || state.status === 'unsupported',
+  };
+}
+
+/**
+ * Whether the receiver is producing FM audio (the state that must not overlap
+ * internet-radio playback).
+ * @param {object} state SdrController.getState() snapshot.
+ * @returns {boolean}
+ */
+export function localSdrFmAudioActive(state) {
+  return Boolean(
+    state?.connected && state.mode === 'fm' && state.status === 'streaming',
+  );
+}
+
+/**
+ * Whether internet radio is loading or playing a station.
+ * @param {object} state Radio UI state.
+ * @returns {boolean}
+ */
+export function internetRadioAudioActive(state) {
+  return ['loading', 'buffering', 'playing'].includes(state?.audioState);
+}
+
+/**
+ * One-line decoder-feed summary for the card, or null when the server has no
+ * feed configured. Statuses show while Local ADS-B polls the feeds; otherwise
+ * the line names the configured bands.
+ * @param {object|null} feedState Local receiver feed session snapshot.
+ * @returns {string|null}
+ */
+export function localSdrFeedLine(feedState) {
+  const feeds = feedState?.configured === true ? feedState.feeds : null;
+  if (!Array.isArray(feeds) || !feeds.length) return null;
+  const names = feeds.map((feed) => {
+    const name = localReceiverFeedName(feed, feeds);
+    return feedState.polling || feed?.status === 'invalid'
+      ? `${name} ${feed?.status || 'unreachable'}`
+      : name;
+  });
+  const suffix = feedState.polling ? '' : ' · read while Local ADS-B is on';
+  return `Decoder feeds: ${names.join(' · ')}${suffix}`;
+}