[feat](trx-rs): add AIS decoder mode and frontend

Add dual-channel AIS decode support across the SoapySDR backend, server decode pipeline, and frontend plugins, including the new AIS tab, live bar, and map filtering.

Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/src/audio_client.rs

@@ -18,9 +18,9 @@ use tracing::{info, warn};
 use trx_frontend::RemoteRigEntry;
 
 use trx_core::audio::{
-    read_audio_msg, write_audio_msg, AudioStreamInfo, AUDIO_MSG_APRS_DECODE, AUDIO_MSG_CW_DECODE,
-    AUDIO_MSG_FT8_DECODE, AUDIO_MSG_RX_FRAME, AUDIO_MSG_STREAM_INFO, AUDIO_MSG_TX_FRAME,
-    AUDIO_MSG_WSPR_DECODE,
+    read_audio_msg, write_audio_msg, AudioStreamInfo, AUDIO_MSG_AIS_DECODE,
+    AUDIO_MSG_APRS_DECODE, AUDIO_MSG_CW_DECODE, AUDIO_MSG_FT8_DECODE, AUDIO_MSG_RX_FRAME,
+    AUDIO_MSG_STREAM_INFO, AUDIO_MSG_TX_FRAME, AUDIO_MSG_WSPR_DECODE,
 };
 use trx_core::decode::DecodedMessage;
 
@@ -148,7 +148,8 @@ async fn handle_audio_connection(
                     let _ = rx_tx.send(Bytes::from(payload));
                 }
                 Ok((
-                    AUDIO_MSG_APRS_DECODE
+                    AUDIO_MSG_AIS_DECODE
+                    | AUDIO_MSG_APRS_DECODE
                     | AUDIO_MSG_CW_DECODE
                     | AUDIO_MSG_FT8_DECODE
                     | AUDIO_MSG_WSPR_DECODE,

src/trx-client/trx-frontend/src/lib.rs

@@ -13,7 +13,7 @@ use tokio::sync::{broadcast, mpsc, watch};
 use tokio::task::JoinHandle;
 
 use trx_core::audio::AudioStreamInfo;
-use trx_core::decode::{AprsPacket, CwEvent, DecodedMessage, Ft8Message, WsprMessage};
+use trx_core::decode::{AisMessage, AprsPacket, CwEvent, DecodedMessage, Ft8Message, WsprMessage};
 use trx_core::rig::state::{RigSnapshot, SpectrumData};
 use trx_core::{DynResult, RigRequest, RigState};
 
@@ -136,6 +136,8 @@ pub struct FrontendRuntimeContext {
     pub audio_info: Option<watch::Receiver<Option<AudioStreamInfo>>>,
     /// Decode message broadcast channel
     pub decode_rx: Option<broadcast::Sender<DecodedMessage>>,
+    /// AIS decode history (timestamp, message)
+    pub ais_history: Arc<Mutex<VecDeque<(Instant, AisMessage)>>>,
     /// APRS decode history (timestamp, packet)
     pub aprs_history: Arc<Mutex<VecDeque<(Instant, AprsPacket)>>>,
     /// CW decode history (timestamp, event)
@@ -196,6 +198,7 @@ impl FrontendRuntimeContext {
             audio_tx: None,
             audio_info: None,
             decode_rx: None,
+            ais_history: Arc::new(Mutex::new(VecDeque::new())),
             aprs_history: Arc::new(Mutex::new(VecDeque::new())),
             cw_history: Arc::new(Mutex::new(VecDeque::new())),
             ft8_history: Arc::new(Mutex::new(VecDeque::new())),

src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js

@@ -845,10 +845,11 @@ function drawSignalOverlay() {
 
   if (lastFreqHz != null && currentBandwidthHz > 0) {
     const halfBw = currentBandwidthHz / 2;
-    const xL = hzToX(lastFreqHz - halfBw);
-    const xR = hzToX(lastFreqHz + halfBw);
-    const stripW = xR - xL;
-    if (stripW > 1) {
+    for (const centerHz of visibleBandwidthCenters(lastFreqHz)) {
+      const xL = hzToX(centerHz - halfBw);
+      const xR = hzToX(centerHz + halfBw);
+      const stripW = xR - xL;
+      if (stripW <= 1) continue;
       const grd = ctx.createLinearGradient(xL, 0, xR, 0);
       grd.addColorStop(0, "rgba(240,173,78,0.05)");
       grd.addColorStop(0.2, "rgba(240,173,78,0.14)");
@@ -1204,6 +1205,31 @@ function coverageGuardBandwidthHz(mode = modeEl ? modeEl.value : "") {
   return Math.max(0, Number.isFinite(maxBw) ? maxBw : currentBandwidthHz);
 }
 
+function isAisMode(mode = modeEl ? modeEl.value : "") {
+  return String(mode || "").toUpperCase() === "AIS";
+}
+
+function coverageSpanForMode(freqHz, bandwidthHz = coverageGuardBandwidthHz(), mode = modeEl ? modeEl.value : "") {
+  if (!Number.isFinite(freqHz)) return null;
+  const safeBw = Math.max(0, Number.isFinite(bandwidthHz) ? bandwidthHz : 0);
+  let loHz = freqHz - safeBw / 2;
+  let hiHz = freqHz + safeBw / 2;
+  if (isAisMode(mode)) {
+    const aisBFreqHz = freqHz + 50_000;
+    loHz = Math.min(loHz, aisBFreqHz - safeBw / 2);
+    hiHz = Math.max(hiHz, aisBFreqHz + safeBw / 2);
+  }
+  return { loHz, hiHz };
+}
+
+function visibleBandwidthCenters(freqHz = lastFreqHz, mode = modeEl ? modeEl.value : "") {
+  if (!Number.isFinite(freqHz)) return [];
+  if (isAisMode(mode)) {
+    return [freqHz, freqHz + 50_000];
+  }
+  return [freqHz];
+}
+
 function effectiveSpectrumCoverageSpanHz(sampleRateHz) {
   const sampleRate = Number(sampleRateHz);
   if (!Number.isFinite(sampleRate) || sampleRate <= 0) return 0;
@@ -1220,17 +1246,17 @@ function requiredCenterFreqForCoverageInFrame(data, freqHz, bandwidthHz = covera
     return null;
   }
 
-  const safeBw = Math.max(0, Number.isFinite(bandwidthHz) ? bandwidthHz : 0);
   const halfSpanHz = sampleRate / 2;
-  const requiredHalfSpanHz = safeBw / 2 + spectrumCoverageMarginHz;
-  if (requiredHalfSpanHz * 2 >= sampleRate) {
+  const span = coverageSpanForMode(freqHz, bandwidthHz);
+  if (!span) return null;
+  const requiredLoHz = span.loHz - spectrumCoverageMarginHz;
+  const requiredHiHz = span.hiHz + spectrumCoverageMarginHz;
+  if (requiredHiHz - requiredLoHz >= sampleRate) {
     return alignFreqToRigStep(Math.round(freqHz));
   }
 
   const currentLoHz = currentCenterHz - halfSpanHz;
   const currentHiHz = currentCenterHz + halfSpanHz;
-  const requiredLoHz = freqHz - requiredHalfSpanHz;
-  const requiredHiHz = freqHz + requiredHalfSpanHz;
   if (requiredLoHz >= currentLoHz && requiredHiHz <= currentHiHz) {
     return null;
   }
@@ -1300,8 +1326,11 @@ function sweetSpotCandidateForFrame(data, freqHz, bandwidthHz) {
 
   const halfUsableSpanHz = usableSpanHz / 2;
   const fullHalfSpanHz = sampleRate / 2;
-  const guardHalfSpanHz = bandwidthHz / 2 + spectrumCoverageMarginHz;
-  if (guardHalfSpanHz * 2 >= usableSpanHz) {
+  const span = coverageSpanForMode(freqHz, bandwidthHz);
+  if (!span) return null;
+  const requiredLoHz = span.loHz - spectrumCoverageMarginHz;
+  const requiredHiHz = span.hiHz + spectrumCoverageMarginHz;
+  if (requiredHiHz - requiredLoHz >= usableSpanHz) {
     const fallbackCenterHz = requiredCenterFreqForCoverageInFrame(data, freqHz, bandwidthHz);
     if (!Number.isFinite(fallbackCenterHz)) return null;
     return { centerHz: fallbackCenterHz, score: Number.POSITIVE_INFINITY };
@@ -1310,8 +1339,8 @@ function sweetSpotCandidateForFrame(data, freqHz, bandwidthHz) {
   const evalHalfSpanHz = Math.max(0, (sampleRate - usableSpanHz) / 2);
   const evalMinCenterHz = currentCenterHz - evalHalfSpanHz;
   const evalMaxCenterHz = currentCenterHz + evalHalfSpanHz;
-  const fitMinCenterHz = freqHz + guardHalfSpanHz - halfUsableSpanHz;
-  const fitMaxCenterHz = freqHz - guardHalfSpanHz + halfUsableSpanHz;
+  const fitMinCenterHz = requiredHiHz - halfUsableSpanHz;
+  const fitMaxCenterHz = requiredLoHz + halfUsableSpanHz;
   const minCenterHz = Math.max(evalMinCenterHz, fitMinCenterHz);
   const maxCenterHz = Math.min(evalMaxCenterHz, fitMaxCenterHz);
   if (!Number.isFinite(minCenterHz) || !Number.isFinite(maxCenterHz) || minCenterHz > maxCenterHz) {
@@ -1334,8 +1363,8 @@ function sweetSpotCandidateForFrame(data, freqHz, bandwidthHz) {
 
   let bestStartIdx = null;
   let bestScore = Number.POSITIVE_INFINITY;
-  const signalLoHz = freqHz - bandwidthHz / 2;
-  const signalHiHz = freqHz + bandwidthHz / 2;
+  const signalLoHz = span.loHz;
+  const signalHiHz = span.hiHz;
 
   for (let startIdx = startMinIdx; startIdx <= startMaxIdx; startIdx += 1) {
     const endIdx = Math.min(maxIdx, startIdx + usableBins);
@@ -1351,7 +1380,8 @@ function sweetSpotCandidateForFrame(data, freqHz, bandwidthHz) {
     }
 
     // Keep a very small bias toward a reasonably centered passband when scores are close.
-    const centeredOffsetHz = Math.abs(candidateCenterHz - freqHz);
+    const spanMidHz = (span.loHz + span.hiHz) / 2;
+    const centeredOffsetHz = Math.abs(candidateCenterHz - spanMidHz);
     score *= 1 + centeredOffsetHz / Math.max(usableSpanHz, 1) * 0.08;
     if (score < bestScore) {
       bestScore = score;
@@ -1388,13 +1418,16 @@ function sweetSpotProbeCenters(data, freqHz, bandwidthHz) {
   if (!Number.isFinite(usableSpanHz) || usableSpanHz <= 0) return [];
 
   const halfUsableSpanHz = usableSpanHz / 2;
-  const guardHalfSpanHz = bandwidthHz / 2 + spectrumCoverageMarginHz;
-  if (guardHalfSpanHz * 2 >= usableSpanHz) {
+  const span = coverageSpanForMode(freqHz, bandwidthHz);
+  if (!span) return [];
+  const requiredLoHz = span.loHz - spectrumCoverageMarginHz;
+  const requiredHiHz = span.hiHz + spectrumCoverageMarginHz;
+  if (requiredHiHz - requiredLoHz >= usableSpanHz) {
     return [alignFreqToRigStep(Math.round(freqHz))];
   }
 
-  const minCenterHz = freqHz + guardHalfSpanHz - halfUsableSpanHz;
-  const maxCenterHz = freqHz - guardHalfSpanHz + halfUsableSpanHz;
+  const minCenterHz = requiredHiHz - halfUsableSpanHz;
+  const maxCenterHz = requiredLoHz + halfUsableSpanHz;
   if (!Number.isFinite(minCenterHz) || !Number.isFinite(maxCenterHz) || minCenterHz > maxCenterHz) {
     return [];
   }
@@ -1486,15 +1519,17 @@ function tunedFrequencyForCenterCoverage(centerHz, freqHz = lastFreqHz, bandwidt
   const sampleRate = effectiveSpectrumCoverageSpanHz(lastSpectrumData.sample_rate);
   if (!Number.isFinite(sampleRate) || sampleRate <= 0) return null;
 
-  const safeBw = Math.max(0, Number.isFinite(bandwidthHz) ? bandwidthHz : 0);
+  const span = coverageSpanForMode(freqHz, bandwidthHz);
+  if (!span) return null;
   const halfSpanHz = sampleRate / 2;
-  const requiredHalfSpanHz = safeBw / 2 + spectrumCoverageMarginHz;
-  if (requiredHalfSpanHz * 2 >= sampleRate) {
+  const requiredLoOffset = freqHz - (span.loHz - spectrumCoverageMarginHz);
+  const requiredHiOffset = (span.hiHz + spectrumCoverageMarginHz) - freqHz;
+  if (requiredLoOffset + requiredHiOffset >= sampleRate) {
     return alignFreqToRigStep(Math.round(centerHz));
   }
 
-  const minFreqHz = centerHz - halfSpanHz + requiredHalfSpanHz;
-  const maxFreqHz = centerHz + halfSpanHz - requiredHalfSpanHz;
+  const minFreqHz = centerHz - halfSpanHz + requiredLoOffset;
+  const maxFreqHz = centerHz + halfSpanHz - requiredHiOffset;
   if (freqHz >= minFreqHz && freqHz <= maxFreqHz) {
     return null;
   }
@@ -1953,10 +1988,15 @@ function render(update) {
     }
   }
   const modeUpper = update.status && update.status.mode ? normalizeMode(update.status.mode).toUpperCase() : "";
+  const aisStatus = document.getElementById("ais-status");
   const aprsStatus = document.getElementById("aprs-status");
   const cwStatus = document.getElementById("cw-status");
   const ft8Status = document.getElementById("ft8-status");
   const wsprStatus = document.getElementById("wspr-status");
+  if (aisStatus && modeUpper !== "AIS" && aisStatus.textContent === "Receiving") {
+    aisStatus.textContent = "Connected, listening for packets";
+  }
+  if (window.updateAisBar) window.updateAisBar();
   if (aprsStatus && modeUpper !== "PKT" && aprsStatus.textContent === "Receiving") {
     aprsStatus.textContent = "Connected, listening for packets";
   }
@@ -2644,6 +2684,7 @@ const MODE_BW_DEFAULTS = {
   USB:    [2_700,  300,   6_000,  100],
   AM:     [9_000,  500,   20_000, 500],
   FM:     [12_500, 2_500, 25_000, 500],
+  AIS:    [25_000, 12_500, 50_000, 500],
   WFM:    [180_000, 50_000,300_000,5_000],
   DIG:    [3_000,  300,   6_000,  100],
   PKT:    [25_000, 300,  50_000,  500],
@@ -2925,8 +2966,9 @@ let aprsRadioPath = null;
 const stationMarkers = new Map();
 const locatorMarkers = new Map();
 const mapMarkers = new Set();
-const mapFilter = { aprs: true, ft8: true, wspr: true };
+const mapFilter = { ais: true, aprs: true, ft8: true, wspr: true };
 const APRS_TRACK_MAX_POINTS = 64;
+const aisMarkers = new Map();
 
 window.clearMapMarkersByType = function(type) {
   if (type === "aprs") {
@@ -2944,6 +2986,17 @@ window.clearMapMarkersByType = function(type) {
     return;
   }
 
+  if (type === "ais") {
+    aisMarkers.forEach((entry) => {
+      if (entry && entry.marker) {
+        if (aprsMap && aprsMap.hasLayer(entry.marker)) entry.marker.removeFrom(aprsMap);
+        mapMarkers.delete(entry.marker);
+      }
+    });
+    aisMarkers.clear();
+    return;
+  }
+
   if (type === "ft8" || type === "wspr") {
     const prefix = `${type}:`;
     for (const [key, entry] of locatorMarkers.entries()) {
@@ -3041,9 +3094,16 @@ function initAprsMap() {
   }
   applyMapFilter();
 
+  const aisFilter = document.getElementById("map-filter-ais");
   const aprsFilter = document.getElementById("map-filter-aprs");
   const ft8Filter = document.getElementById("map-filter-ft8");
   const wsprFilter = document.getElementById("map-filter-wspr");
+  if (aisFilter) {
+    aisFilter.addEventListener("change", () => {
+      mapFilter.ais = aisFilter.checked;
+      applyMapFilter();
+    });
+  }
   if (aprsFilter) {
     aprsFilter.addEventListener("change", () => {
       mapFilter.aprs = aprsFilter.checked;
@@ -3188,6 +3248,30 @@ function buildAprsPopupHtml(call, lat, lon, info, pkt) {
     `</div>`;
 }
 
+function buildAisPopupHtml(msg) {
+  const age = msg?._tsMs ? formatTimeAgo(msg._tsMs) : null;
+  const distKm = (serverLat != null && serverLon != null && msg?.lat != null && msg?.lon != null)
+    ? haversineKm(serverLat, serverLon, msg.lat, msg.lon)
+    : null;
+  const distStr = distKm != null
+    ? (distKm < 1 ? `${Math.round(distKm * 1000)} m` : `${distKm.toFixed(1)} km`)
+    : null;
+  const meta = [age, distStr, msg?.channel ? `AIS ${escapeMapHtml(msg.channel)}` : null].filter(Boolean).join(" &middot; ");
+  let rows = "";
+  rows += `<tr><td class="aprs-popup-label">MMSI</td><td>${escapeMapHtml(String(msg.mmsi || "--"))}</td></tr>`;
+  rows += `<tr><td class="aprs-popup-label">Type</td><td>${escapeMapHtml(String(msg.message_type || "--"))}</td></tr>`;
+  if (msg?.sog_knots != null) rows += `<tr><td class="aprs-popup-label">SOG</td><td>${Number(msg.sog_knots).toFixed(1)} kn</td></tr>`;
+  if (msg?.cog_deg != null) rows += `<tr><td class="aprs-popup-label">COG</td><td>${Number(msg.cog_deg).toFixed(1)}&deg;</td></tr>`;
+  if (msg?.lat != null && msg?.lon != null) rows += `<tr><td class="aprs-popup-label">Pos</td><td>${msg.lat.toFixed(5)}, ${msg.lon.toFixed(5)}</td></tr>`;
+  const info = [msg?.vessel_name, msg?.callsign, msg?.destination].filter(Boolean).map(escapeMapHtml).join(" · ");
+  return `<div class="aprs-popup">` +
+    `<div class="aprs-popup-call">${escapeMapHtml(msg?.vessel_name || `MMSI ${msg?.mmsi || "--"}`)}</div>` +
+    (meta ? `<div class="aprs-popup-meta">${meta}</div>` : "") +
+    (rows ? `<table class="aprs-popup-table">${rows}</table>` : "") +
+    (info ? `<div class="aprs-popup-info">${info}</div>` : "") +
+    `</div>`;
+}
+
 function aprsPositionsEqual(a, b) {
   if (!a || !b) return false;
   return Math.abs(a[0] - b[0]) < 0.000001 && Math.abs(a[1] - b[1]) < 0.000001;
@@ -3276,6 +3360,31 @@ window.aprsMapAddStation = function(call, lat, lon, info, symbolTable, symbolCod
   }
 };
 
+window.aisMapAddVessel = function(msg) {
+  if (msg == null || msg.lat == null || msg.lon == null || !Number.isFinite(msg.mmsi)) return;
+  if (!aprsMap) initAprsMap();
+  const key = String(msg.mmsi);
+  const popupHtml = buildAisPopupHtml(msg);
+  const existing = aisMarkers.get(key);
+  if (existing && existing.marker) {
+    existing.msg = msg;
+    existing.marker.setLatLng([msg.lat, msg.lon]);
+    existing.marker.setPopupContent(popupHtml);
+    return;
+  }
+  if (!aprsMap) return;
+  const marker = L.circleMarker([msg.lat, msg.lon], {
+    radius: 6,
+    color: "#e2553d",
+    fillColor: "#ff7559",
+    fillOpacity: 0.82,
+  }).addTo(aprsMap).bindPopup(popupHtml);
+  marker.__trxType = "ais";
+  mapMarkers.add(marker);
+  aisMarkers.set(key, { marker, msg });
+  applyMapFilter();
+};
+
 function maidenheadToBounds(grid) {
   if (!grid || grid.length < 4) return null;
   const g = grid.toUpperCase();
@@ -3310,6 +3419,7 @@ function applyMapFilter() {
   mapMarkers.forEach((marker) => {
     const type = marker.__trxType;
     const visible =
+      (type === "ais" && mapFilter.ais) ||
       (type === "aprs" && mapFilter.aprs) ||
       (type === "ft8" && mapFilter.ft8) ||
       (type === "wspr" && mapFilter.wspr);
@@ -3999,15 +4109,18 @@ document.getElementById("copyright-year").textContent = new Date().getFullYear()
 let decodeSource = null;
 let decodeConnected = false;
 function updateDecodeStatus(text) {
+  const ais = document.getElementById("ais-status");
   const aprs = document.getElementById("aprs-status");
   const cw = document.getElementById("cw-status");
   const ft8 = document.getElementById("ft8-status");
+  if (ais && ais.textContent !== "Receiving") ais.textContent = text;
   if (aprs && aprs.textContent !== "Receiving") aprs.textContent = text;
   if (cw && cw.textContent !== "Receiving") cw.textContent = text;
   if (ft8 && ft8.textContent !== "Receiving") ft8.textContent = text;
 }
 function connectDecode() {
   if (decodeSource) { decodeSource.close(); }
+  if (window.resetAisHistoryView) window.resetAisHistoryView();
   if (window.resetAprsHistoryView) window.resetAprsHistoryView();
   if (window.resetCwHistoryView) window.resetCwHistoryView();
   if (window.resetFt8HistoryView) window.resetFt8HistoryView();
@@ -4020,6 +4133,7 @@ function connectDecode() {
   decodeSource.onmessage = (evt) => {
     try {
       const msg = JSON.parse(evt.data);
+      if (msg.type === "ais" && window.onServerAis) window.onServerAis(msg);
       if (msg.type === "aprs" && window.onServerAprs) window.onServerAprs(msg);
       if (msg.type === "cw" && window.onServerCw) window.onServerCw(msg);
       if (msg.type === "ft8" && window.onServerFt8) window.onServerFt8(msg);
@@ -4796,36 +4910,38 @@ function drawSpectrum(data) {
   // ── BW strip (drawn before spectrum so traces appear on top) ──────────────
   if (lastFreqHz != null && currentBandwidthHz > 0) {
     if (_bwDragEdge) {
-      const xMid = hzToX(lastFreqHz);
-      // Bottom bookmark tab centered on the dial frequency, shown only while resizing BW
+      // Bottom bookmark tab centered on each visible channel, shown while resizing BW
       const bwText = formatBwLabel(currentBandwidthHz);
-      ctx.save();
-      ctx.font = `bold ${Math.round(10 * dpr)}px sans-serif`;
-      const tw = ctx.measureText(bwText).width;
-      const PAD  = 6 * dpr;
-      const TAB_H = 16 * dpr;
-      const TAB_OFFSET = 4 * dpr;
-      const tabX = Math.max(0, Math.min(W - tw - PAD * 2, xMid - (tw + PAD * 2) / 2));
-      const tabBottom = H - TAB_OFFSET;
-      const tabY = tabBottom - TAB_H;
-      const r = 3 * dpr;
-      // Rounded-bottom tab shape (flat top)
-      ctx.fillStyle = "rgba(240,173,78,0.85)";
-      ctx.beginPath();
-      ctx.moveTo(tabX, tabY);
-      ctx.lineTo(tabX + tw + PAD * 2, tabY);
-      ctx.lineTo(tabX + tw + PAD * 2, tabBottom - r);
-      ctx.arcTo(tabX + tw + PAD * 2, tabBottom, tabX + tw + PAD * 2 - r, tabBottom, r);
-      ctx.lineTo(tabX + r, tabBottom);
-      ctx.arcTo(tabX, tabBottom, tabX, tabBottom - r, r);
-      ctx.lineTo(tabX, tabY);
-      ctx.closePath();
-      ctx.fill();
-      // Tab text
-      ctx.fillStyle = spectrumBgColor();
-      ctx.textAlign = "left";
-      ctx.fillText(bwText, tabX + PAD, tabBottom - 4 * dpr);
-      ctx.restore();
+      for (const centerHz of visibleBandwidthCenters(lastFreqHz)) {
+        const xMid = hzToX(centerHz);
+        ctx.save();
+        ctx.font = `bold ${Math.round(10 * dpr)}px sans-serif`;
+        const tw = ctx.measureText(bwText).width;
+        const PAD  = 6 * dpr;
+        const TAB_H = 16 * dpr;
+        const TAB_OFFSET = 4 * dpr;
+        const tabX = Math.max(0, Math.min(W - tw - PAD * 2, xMid - (tw + PAD * 2) / 2));
+        const tabBottom = H - TAB_OFFSET;
+        const tabY = tabBottom - TAB_H;
+        const r = 3 * dpr;
+        // Rounded-bottom tab shape (flat top)
+        ctx.fillStyle = "rgba(240,173,78,0.85)";
+        ctx.beginPath();
+        ctx.moveTo(tabX, tabY);
+        ctx.lineTo(tabX + tw + PAD * 2, tabY);
+        ctx.lineTo(tabX + tw + PAD * 2, tabBottom - r);
+        ctx.arcTo(tabX + tw + PAD * 2, tabBottom, tabX + tw + PAD * 2 - r, tabBottom, r);
+        ctx.lineTo(tabX + r, tabBottom);
+        ctx.arcTo(tabX, tabBottom, tabX, tabBottom - r, r);
+        ctx.lineTo(tabX, tabY);
+        ctx.closePath();
+        ctx.fill();
+        // Tab text
+        ctx.fillStyle = spectrumBgColor();
+        ctx.textAlign = "left";
+        ctx.fillText(bwText, tabX + PAD, tabBottom - 4 * dpr);
+        ctx.restore();
+      }
     }
   }
 
@@ -5188,11 +5304,24 @@ if (overviewCanvas) {
 function getBwEdgeHit(cssX, cssW, range) {
   if (!lastFreqHz || !currentBandwidthHz || !lastSpectrumData) return null;
   const halfBw = currentBandwidthHz / 2;
-  const xL = ((lastFreqHz - halfBw - range.visLoHz) / range.visSpanHz) * cssW;
-  const xR = ((lastFreqHz + halfBw - range.visLoHz) / range.visSpanHz) * cssW;
   const HIT = 8;
-  if (Math.abs(cssX - xL) < HIT) return "left";
-  if (Math.abs(cssX - xR) < HIT) return "right";
+  let bestEdge = null;
+  let bestDist = Number.POSITIVE_INFINITY;
+  for (const centerHz of visibleBandwidthCenters(lastFreqHz)) {
+    const xL = ((centerHz - halfBw - range.visLoHz) / range.visSpanHz) * cssW;
+    const xR = ((centerHz + halfBw - range.visLoHz) / range.visSpanHz) * cssW;
+    const distL = Math.abs(cssX - xL);
+    const distR = Math.abs(cssX - xR);
+    if (distL < HIT && distL < bestDist) {
+      bestEdge = "left";
+      bestDist = distL;
+    }
+    if (distR < HIT && distR < bestDist) {
+      bestEdge = "right";
+      bestDist = distR;
+    }
+  }
+  if (bestEdge) return bestEdge;
   return null;
 }
 

src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html

@@ -78,6 +78,7 @@
       <div class="overview-strip">
         <canvas id="overview-canvas" aria-hidden="true"></canvas>
         <div id="rds-ps-overlay" aria-live="polite" aria-label="RDS station name"></div>
+        <div id="ais-bar-overlay" aria-live="polite" aria-label="Recent AIS messages"></div>
         <div id="aprs-bar-overlay" aria-live="polite" aria-label="Recent APRS frames"></div>
       </div>
       <div id="spectrum-bookmark-axis"></div>
@@ -348,6 +349,7 @@
     <div id="tab-plugins" class="tab-panel" style="display:none;">
       <div class="sub-tab-bar">
         <button class="sub-tab active" data-subtab="overview">Overview</button>
+        <button class="sub-tab" data-subtab="ais">AIS</button>
         <button class="sub-tab" data-subtab="aprs">APRS</button>
         <button class="sub-tab" data-subtab="cw">CW</button>
         <button class="sub-tab" data-subtab="ft8">FT8</button>
@@ -355,6 +357,12 @@
         <button class="sub-tab" data-subtab="rds">RDS</button>
       </div>
       <div id="subtab-overview" class="sub-tab-panel">
+        <div class="plugin-item">
+          <strong>AIS Decoder</strong>
+          <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
+            Decodes dual-channel AIS traffic from RX audio using 9.6 kbit/s GMSK and HDLC.
+          </div>
+        </div>
         <div class="plugin-item">
           <strong>APRS Decoder</strong>
           <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
@@ -411,6 +419,14 @@
         </div>
         <pre id="rds-raw" class="rds-raw">--</pre>
       </div>
+      <div id="subtab-ais" class="sub-tab-panel" style="display:none;">
+        <div class="aprs-controls">
+          <button id="ais-clear-btn" type="button">Clear</button>
+          <input id="ais-filter" class="ft8-filter" type="text" placeholder="Filter (e.g. MMSI, vessel, A)" />
+          <small id="ais-status" style="color:var(--text-muted);">Waiting for server decode</small>
+        </div>
+        <div id="ais-messages"></div>
+      </div>
       <div id="subtab-aprs" class="sub-tab-panel" style="display:none;">
         <div class="aprs-controls">
           <button id="aprs-clear-btn" type="button">Clear</button>
@@ -469,6 +485,7 @@
     </div>
     <div id="tab-map" class="tab-panel" style="display:none;">
       <div class="map-controls">
+        <label><input type="checkbox" id="map-filter-ais" checked /> AIS</label>
         <label><input type="checkbox" id="map-filter-aprs" checked /> APRS</label>
         <label><input type="checkbox" id="map-filter-ft8" checked /> FT8</label>
         <label><input type="checkbox" id="map-filter-wspr" checked /> WSPR</label>
@@ -504,6 +521,7 @@
     </div>
   </div>
   <script src="/app.js"></script>
+  <script src="/ais.js"></script>
   <script src="/aprs.js"></script>
   <script src="/ft8.js"></script>
   <script src="/wspr.js"></script>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/plugins/ais.js

@@ -0,0 +1,165 @@
+// --- AIS Decoder Plugin (server-side decode) ---
+const aisStatus = document.getElementById("ais-status");
+const aisMessagesEl = document.getElementById("ais-messages");
+const aisFilterInput = document.getElementById("ais-filter");
+const aisClearBtn = document.getElementById("ais-clear-btn");
+const aisBarOverlay = document.getElementById("ais-bar-overlay");
+const AIS_MAX_MESSAGES = 200;
+const AIS_BAR_WINDOW_MS = 15 * 60 * 1000;
+let aisFilterText = "";
+let aisMessageHistory = [];
+
+function aisDisplayName(msg) {
+  return msg.vessel_name || msg.callsign || `MMSI ${msg.mmsi}`;
+}
+
+function renderAisRow(msg) {
+  const row = document.createElement("div");
+  row.className = "ais-message";
+  const ts = msg._ts || new Date().toLocaleTimeString([], { hour: "2-digit", minute: "2-digit", second: "2-digit" });
+  const name = aisDisplayName(msg);
+  const channel = msg.channel ? `AIS-${msg.channel}` : "AIS";
+  const pos = msg.lat != null && msg.lon != null
+    ? ` <a class="aprs-pos" href="javascript:void(0)" onclick="window.navigateToAprsMap(${msg.lat},${msg.lon})">${msg.lat.toFixed(4)}, ${msg.lon.toFixed(4)}</a>`
+    : "";
+  const motion = [
+    msg.sog_knots != null ? `${Number(msg.sog_knots).toFixed(1)} kn` : null,
+    msg.cog_deg != null ? `${Number(msg.cog_deg).toFixed(1)}°` : null,
+  ].filter(Boolean).join(" · ");
+  row.dataset.filterText = [
+    name,
+    msg.mmsi,
+    msg.channel,
+    msg.vessel_name,
+    msg.callsign,
+    msg.destination,
+  ]
+    .filter(Boolean)
+    .join(" ")
+    .toUpperCase();
+  row.innerHTML =
+    `<span class="ais-time">${ts}</span>` +
+    `<span class="ais-call">${escapeMapHtml(name)}</span> ` +
+    `<span class="aprs-time">[${escapeMapHtml(channel)}]</span> ` +
+    `<span>MMSI ${escapeMapHtml(String(msg.mmsi))}</span>` +
+    (motion ? ` <span>${escapeMapHtml(motion)}</span>` : "") +
+    pos;
+  applyAisFilterToRow(row);
+  return row;
+}
+
+function applyAisFilterToRow(row) {
+  if (!aisFilterText) {
+    row.style.display = "";
+    return;
+  }
+  const message = row.dataset.filterText || "";
+  row.style.display = message.includes(aisFilterText) ? "" : "none";
+}
+
+function applyAisFilterToAll() {
+  if (!aisMessagesEl) return;
+  const rows = aisMessagesEl.querySelectorAll(".ais-message");
+  rows.forEach((row) => applyAisFilterToRow(row));
+}
+
+function updateAisBar() {
+  if (!aisBarOverlay) return;
+  const isAis = (document.getElementById("mode")?.value || "").toUpperCase() === "AIS";
+  const cutoffMs = Date.now() - AIS_BAR_WINDOW_MS;
+  const messages = aisMessageHistory.filter((msg) => msg._tsMs >= cutoffMs);
+  if (!isAis || messages.length === 0) {
+    aisBarOverlay.style.display = "none";
+    aisBarOverlay.innerHTML = "";
+    return;
+  }
+
+  let html = '<div class="aprs-bar-header"><span class="aprs-bar-title"><span class="aprs-bar-title-word">AIS</span><span class="aprs-bar-title-word">Live</span></span><span class="aprs-bar-clear-wrap"><span class="aprs-bar-clear" role="button" tabindex="0" onclick="window.clearAisBar()" onkeydown="if(event.key===\'Enter\'||event.key===\' \'){event.preventDefault();window.clearAisBar();}" aria-label="Clear AIS overlay">Clear</span></span><span class="aprs-bar-window">Last 15 minutes</span></div>';
+  for (const msg of messages) {
+    const ts = msg._ts ? `<span class="aprs-bar-time">${msg._ts}</span>` : "";
+    const pin = msg.lat != null && msg.lon != null
+      ? `<button class="aprs-bar-pin" title="${msg.lat.toFixed(4)}, ${msg.lon.toFixed(4)}" onclick="window.navigateToAprsMap(${msg.lat},${msg.lon})">📍</button>`
+      : "";
+    const name = `<span class="ais-call">${escapeMapHtml(aisDisplayName(msg))}</span>`;
+    const channel = msg.channel ? ` AIS-${escapeMapHtml(msg.channel)}` : "";
+    const details = [
+      `MMSI ${escapeMapHtml(String(msg.mmsi))}`,
+      msg.sog_knots != null ? `${Number(msg.sog_knots).toFixed(1)} kn` : null,
+      msg.cog_deg != null ? `${Number(msg.cog_deg).toFixed(1)}°` : null,
+    ].filter(Boolean).join(" · ");
+    html += `<div class="aprs-bar-frame">` +
+      `<div class="aprs-bar-frame-main">${ts}${pin}${name}${channel}: ${details}</div>` +
+      `</div>`;
+  }
+  aisBarOverlay.innerHTML = html;
+  aisBarOverlay.style.display = "flex";
+}
+window.updateAisBar = updateAisBar;
+window.clearAisBar = function() {
+  window.resetAisHistoryView();
+};
+
+window.resetAisHistoryView = function() {
+  if (aisMessagesEl) aisMessagesEl.innerHTML = "";
+  aisMessageHistory = [];
+  updateAisBar();
+  if (window.clearMapMarkersByType) window.clearMapMarkersByType("ais");
+};
+
+function addAisMessage(msg) {
+  const tsMs = Number.isFinite(msg.ts_ms) ? Number(msg.ts_ms) : Date.now();
+  msg._tsMs = tsMs;
+  msg._ts = new Date(tsMs).toLocaleTimeString([], { hour: "2-digit", minute: "2-digit", second: "2-digit" });
+
+  aisMessageHistory.unshift(msg);
+  if (aisMessageHistory.length > AIS_MAX_MESSAGES) aisMessageHistory.length = AIS_MAX_MESSAGES;
+  updateAisBar();
+
+  if (aisMessagesEl) {
+    const row = renderAisRow(msg);
+    aisMessagesEl.prepend(row);
+    while (aisMessagesEl.children.length > AIS_MAX_MESSAGES) {
+      aisMessagesEl.removeChild(aisMessagesEl.lastChild);
+    }
+  }
+
+  if (msg.lat != null && msg.lon != null && window.aisMapAddVessel) {
+    window.aisMapAddVessel(msg);
+  }
+}
+
+if (aisClearBtn) {
+  aisClearBtn.addEventListener("click", async () => {
+    try {
+      await postPath("/clear_ais_decode");
+      window.resetAisHistoryView();
+    } catch (e) {
+      console.error("AIS clear failed", e);
+    }
+  });
+}
+
+if (aisFilterInput) {
+  aisFilterInput.addEventListener("input", () => {
+    aisFilterText = aisFilterInput.value.trim().toUpperCase();
+    applyAisFilterToAll();
+  });
+}
+
+window.onServerAis = function(msg) {
+  if (aisStatus) aisStatus.textContent = "Receiving";
+  addAisMessage({
+    channel: msg.channel,
+    message_type: msg.message_type,
+    mmsi: msg.mmsi,
+    lat: msg.lat,
+    lon: msg.lon,
+    sog_knots: msg.sog_knots,
+    cog_deg: msg.cog_deg,
+    heading_deg: msg.heading_deg,
+    vessel_name: msg.vessel_name,
+    callsign: msg.callsign,
+    destination: msg.destination,
+    ts_ms: msg.ts_ms,
+  });
+};

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -629,7 +629,8 @@ small { color: var(--text-muted); }
   color: var(--text-muted);
   background: color-mix(in srgb, var(--card-bg) 62%, transparent);
 }
-#aprs-bar-overlay {
+#aprs-bar-overlay,
+#ais-bar-overlay {
   display: none;
   position: absolute;
   top: 50%;
@@ -1087,11 +1088,16 @@ small { color: var(--text-muted); }
 .sub-tab:hover:not(.active) { color: var(--text); }
 #aprs-map { min-height: 150px; border-radius: 6px; }
 .aprs-controls { display: flex; gap: 0.6rem; align-items: center; margin-bottom: 0.75rem; }
-#aprs-packets { max-height: 360px; overflow-y: auto; border: 1px solid var(--border-light); border-radius: 6px; background: var(--input-bg); font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; }
+#aprs-packets,
+#ais-messages { max-height: 360px; overflow-y: auto; border: 1px solid var(--border-light); border-radius: 6px; background: var(--input-bg); font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; }
 .aprs-packet { font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; font-size: 0.82rem; padding: 0.35rem 0.5rem; border-bottom: 1px solid var(--border); line-height: 1.4; }
 .aprs-packet:last-child { border-bottom: none; }
+.ais-message { font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; font-size: 0.82rem; padding: 0.35rem 0.5rem; border-bottom: 1px solid var(--border); line-height: 1.4; }
+.ais-message:last-child { border-bottom: none; }
 .aprs-call { color: var(--accent-green); font-weight: 600; }
+.ais-call { color: var(--accent-red); font-weight: 600; }
 .aprs-time { color: var(--text-muted); margin-right: 0.5rem; }
+.ais-time { color: var(--text-muted); margin-right: 0.5rem; }
 .aprs-symbol { display: inline-block; width: 24px; height: 24px; background-size: 384px 192px; vertical-align: middle; margin-right: 0.3rem; }
 .aprs-pos { color: var(--accent-green); text-decoration: none; margin-left: 0.3rem; font-size: 0.8rem; }
 .aprs-pos:hover { text-decoration: underline; }

src/trx-client/trx-frontend/trx-frontend-http/src/api.rs

@@ -258,6 +258,11 @@ pub async fn decode_events(
 
     let history = {
         let mut out = Vec::new();
+        out.extend(
+            crate::server::audio::snapshot_ais_history(context.get_ref())
+                .into_iter()
+                .map(trx_core::decode::DecodedMessage::Ais),
+        );
         out.extend(
             crate::server::audio::snapshot_aprs_history(context.get_ref())
                 .into_iter()
@@ -685,6 +690,14 @@ pub async fn clear_aprs_decode(
     send_command(&rig_tx, RigCommand::ResetAprsDecoder).await
 }
 
+#[post("/clear_ais_decode")]
+pub async fn clear_ais_decode(
+    context: web::Data<Arc<FrontendRuntimeContext>>,
+) -> Result<HttpResponse, Error> {
+    crate::server::audio::clear_ais_history(context.get_ref());
+    Ok(HttpResponse::Ok().finish())
+}
+
 #[post("/clear_cw_decode")]
 pub async fn clear_cw_decode(
     context: web::Data<Arc<FrontendRuntimeContext>>,
@@ -938,6 +951,7 @@ pub fn configure(cfg: &mut web::ServiceConfig) {
         .service(set_cw_tone)
         .service(toggle_ft8_decode)
         .service(toggle_wspr_decode)
+        .service(clear_ais_decode)
         .service(clear_aprs_decode)
         .service(clear_cw_decode)
         .service(clear_ft8_decode)
@@ -954,6 +968,7 @@ pub fn configure(cfg: &mut web::ServiceConfig) {
         .service(logo)
         .service(style_css)
         .service(app_js)
+        .service(ais_js)
         .service(aprs_js)
         .service(ft8_js)
         .service(wspr_js)
@@ -1020,6 +1035,16 @@ async fn aprs_js() -> impl Responder {
         .body(status::APRS_JS)
 }
 
+#[get("/ais.js")]
+async fn ais_js() -> impl Responder {
+    HttpResponse::Ok()
+        .insert_header((
+            header::CONTENT_TYPE,
+            "application/javascript; charset=utf-8",
+        ))
+        .body(status::AIS_JS)
+}
+
 #[get("/ft8.js")]
 async fn ft8_js() -> impl Responder {
     HttpResponse::Ok()

src/trx-client/trx-frontend/trx-frontend-http/src/audio.rs

@@ -20,7 +20,7 @@ use bytes::Bytes;
 use tokio::sync::broadcast;
 use tracing::warn;
 
-use trx_core::decode::{AprsPacket, CwEvent, DecodedMessage, Ft8Message, WsprMessage};
+use trx_core::decode::{AisMessage, AprsPacket, CwEvent, DecodedMessage, Ft8Message, WsprMessage};
 use trx_frontend::FrontendRuntimeContext;
 
 const HISTORY_RETENTION: Duration = Duration::from_secs(24 * 60 * 60);
@@ -34,6 +34,24 @@ fn prune_aprs_history(history: &mut VecDeque<(Instant, AprsPacket)>) {
     }
 }
 
+fn prune_ais_history(history: &mut VecDeque<(Instant, AisMessage)>) {
+    while let Some((ts, _)) = history.front() {
+        if ts.elapsed() <= HISTORY_RETENTION {
+            break;
+        }
+        history.pop_front();
+    }
+}
+
+fn record_ais(context: &FrontendRuntimeContext, msg: AisMessage) {
+    let mut history = context
+        .ais_history
+        .lock()
+        .expect("ais history mutex poisoned");
+    history.push_back((Instant::now(), msg));
+    prune_ais_history(&mut history);
+}
+
 fn prune_cw_history(history: &mut VecDeque<(Instant, CwEvent)>) {
     while let Some((ts, _)) = history.front() {
         if ts.elapsed() <= HISTORY_RETENTION {
@@ -113,6 +131,22 @@ pub fn snapshot_aprs_history(context: &FrontendRuntimeContext) -> Vec<AprsPacket
         .collect()
 }
 
+pub fn snapshot_ais_history(context: &FrontendRuntimeContext) -> Vec<AisMessage> {
+    let mut history = context
+        .ais_history
+        .lock()
+        .expect("ais history mutex poisoned");
+    prune_ais_history(&mut history);
+    history
+        .iter()
+        .map(|(ts, msg)| {
+            let mut msg = msg.clone();
+            msg.ts_ms = Some(timestamp_ms_for_elapsed(ts.elapsed()));
+            msg
+        })
+        .collect()
+}
+
 pub fn snapshot_cw_history(context: &FrontendRuntimeContext) -> Vec<CwEvent> {
     let mut history = context
         .cw_history
@@ -148,6 +182,14 @@ pub fn clear_aprs_history(context: &FrontendRuntimeContext) {
     history.clear();
 }
 
+pub fn clear_ais_history(context: &FrontendRuntimeContext) {
+    let mut history = context
+        .ais_history
+        .lock()
+        .expect("ais history mutex poisoned");
+    history.clear();
+}
+
 fn timestamp_ms_for_elapsed(elapsed: Duration) -> i64 {
     let wall_clock = SystemTime::now()
         .checked_sub(elapsed)
@@ -206,6 +248,7 @@ pub fn start_decode_history_collector(context: Arc<FrontendRuntimeContext>) {
         loop {
             match rx.recv().await {
                 Ok(msg) => match msg {
+                    DecodedMessage::Ais(msg) => record_ais(&context, msg),
                     DecodedMessage::Aprs(pkt) => record_aprs(&context, pkt),
                     DecodedMessage::Cw(evt) => record_cw(&context, evt),
                     DecodedMessage::Ft8(msg) => record_ft8(&context, msg),

src/trx-client/trx-frontend/trx-frontend-http/src/status.rs

@@ -9,6 +9,7 @@ const CLIENT_BUILD_DATE: &str = env!("TRX_CLIENT_BUILD_DATE");
 const INDEX_HTML: &str = include_str!("../assets/web/index.html");
 pub const STYLE_CSS: &str = include_str!("../assets/web/style.css");
 pub const APP_JS: &str = include_str!("../assets/web/app.js");
+pub const AIS_JS: &str = include_str!("../assets/web/plugins/ais.js");
 pub const APRS_JS: &str = include_str!("../assets/web/plugins/aprs.js");
 pub const FT8_JS: &str = include_str!("../assets/web/plugins/ft8.js");
 pub const WSPR_JS: &str = include_str!("../assets/web/plugins/wspr.js");