diff --git a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/generated/app.js b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/generated/app.js
index 23604021..29b3e30b 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/generated/app.js
+++ b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/generated/app.js
@@ -2244,6 +2244,7 @@ function formatSigStrength(dbm) {
   return `${dbfs.toFixed(1)} ${sigUnit("dBFS")}`;
 }
 function refreshSigStrengthDisplay() {
+  renderSdrSquelch();
   if (!sigStrengthEl) return;
   sigStrengthEl.innerHTML = formatSigStrength(sigLastDbm);
 }
@@ -6209,11 +6210,14 @@ var modeControlsRow = document.getElementById("mode-controls-row");
 var samStereoWidthEl = document.getElementById("sam-stereo-width");
 var samCarrierSyncEl = document.getElementById("sam-carrier-sync");
 var sdrSquelchWrapEl = document.getElementById("sdr-squelch-wrap");
-var sdrSquelchEl = document.getElementById("sdr-squelch");
-var sdrSquelchPctEl = document.getElementById("sdr-squelch-pct");
+var sdrSquelchDbEl = document.getElementById("sdr-squelch-db");
+var sdrSquelchStateEl = document.getElementById("sdr-squelch-state");
+var sdrSquelchToggleBtn = document.getElementById("sdr-squelch-toggle");
+var squelchLineEl = document.getElementById("spectrum-squelch-line");
+var squelchGripEl = document.getElementById("spectrum-squelch-grip");
+var squelchLabelEl = document.getElementById("spectrum-squelch-label");
 var SDR_SQUELCH_MIN_DB = -120;
 var SDR_SQUELCH_MAX_DB = -30;
-var syncFromServerSdrSquelch = false;
 var sdrNbWrapEl = document.getElementById("sdr-nb-wrap");
 var sdrNbEnabledEl = document.getElementById("sdr-nb-enabled");
 var sdrNbThresholdControlsEl = document.getElementById("sdr-nb-threshold-controls");
@@ -6302,89 +6306,162 @@ function normalizeWfmDenoiseLevel(value) {
   if (next === "off" || next === "auto" || next === "low" || next === "medium" || next === "high") return next;
   return "auto";
 }
-function clampSdrSquelchPercent(value) {
-  if (!isFiniteNumber(value)) return 0;
-  return Math.max(0, Math.min(100, Math.round(value)));
+var sdrSquelchEnabled = loadSetting("sdrSquelchEnabled", false);
+var sdrSquelchThresholdDb = clampSdrSquelchDb(Number(loadSetting("sdrSquelchThresholdDb", -95)));
+function clampSdrSquelchDb(value) {
+  if (!isFiniteNumber(value)) return SDR_SQUELCH_MIN_DB;
+  return Math.max(SDR_SQUELCH_MIN_DB, Math.min(SDR_SQUELCH_MAX_DB, Math.round(value)));
 }
-function sdrSquelchPercentToServer(percent) {
-  const pct = clampSdrSquelchPercent(percent);
-  if (pct <= 0) {
-    return { enabled: false, thresholdDb: SDR_SQUELCH_MIN_DB };
+function sdrSquelchIsPassing() {
+  if (!sdrSquelchEnabled) return true;
+  if (!isFiniteNumber(sigLastDbm)) return false;
+  return sigLastDbm >= sdrSquelchThresholdDb;
+}
+function renderSdrSquelch() {
+  if (sdrSquelchDbEl && document.activeElement !== sdrSquelchDbEl) {
+    sdrSquelchDbEl.value = String(sdrSquelchThresholdDb);
   }
-  const ratio = pct / 100;
-  const thresholdDb = SDR_SQUELCH_MIN_DB + ratio * (SDR_SQUELCH_MAX_DB - SDR_SQUELCH_MIN_DB);
-  return { enabled: true, thresholdDb };
+  if (sdrSquelchDbEl) sdrSquelchDbEl.disabled = !sdrSquelchSupported;
+  if (sdrSquelchToggleBtn) {
+    sdrSquelchToggleBtn.textContent = sdrSquelchEnabled ? "On" : "Off";
+    sdrSquelchToggleBtn.setAttribute("aria-pressed", String(sdrSquelchEnabled));
+  }
+  const state = !sdrSquelchEnabled ? "off" : sdrSquelchIsPassing() ? "open" : "closed";
+  if (sdrSquelchStateEl) {
+    sdrSquelchStateEl.dataset.state = state;
+    sdrSquelchStateEl.setAttribute(
+      "aria-label",
+      state === "off" ? "Squelch off" : state === "open" ? "Squelch open" : "Squelch closed"
+    );
+  }
+  if (squelchLabelEl) squelchLabelEl.textContent = String(sdrSquelchThresholdDb);
+  if (squelchGripEl) squelchGripEl.setAttribute("aria-valuenow", String(sdrSquelchThresholdDb));
+  if (squelchLineEl) squelchLineEl.dataset.state = state === "open" ? "open" : "closed";
+  positionSquelchLine();
 }
-function sdrSquelchServerToPercent(enabled, thresholdDb) {
-  if (!enabled) return 0;
-  if (!isFiniteNumber(thresholdDb)) return 0;
-  const ratio = (thresholdDb - SDR_SQUELCH_MIN_DB) / (SDR_SQUELCH_MAX_DB - SDR_SQUELCH_MIN_DB);
-  return clampSdrSquelchPercent(ratio * 100);
+function positionSquelchLine() {
+  if (!squelchLineEl) return;
+  const mode = (modeEl && modeEl.value ? modeEl.value : "").toUpperCase();
+  const canvas = document.getElementById("spectrum-canvas");
+  const visible = sdrSquelchSupported && sdrSquelchEnabled && mode !== "WFM" && !!canvas && canvas.clientHeight > 0 && getComputedStyle(requiredElement("spectrum-panel")).display !== "none";
+  if (!visible) {
+    squelchLineEl.style.display = "none";
+    return;
+  }
+  const dbMin = spectrumFloor;
+  const dbMax = spectrumFloor + spectrumRange;
+  const frac = Math.max(0, Math.min(1, (sdrSquelchThresholdDb - dbMin) / Math.max(1, dbMax - dbMin)));
+  squelchLineEl.style.display = "";
+  squelchLineEl.style.top = `${canvas.offsetTop + canvas.clientHeight * (1 - frac)}px`;
 }
-function updateSdrSquelchPctLabel() {
-  if (!sdrSquelchEl || !sdrSquelchPctEl) return;
-  const pct = clampSdrSquelchPercent(Number(sdrSquelchEl.value));
-  sdrSquelchPctEl.textContent = pct <= 0 ? "Open" : `${pct}%`;
+function submitSdrSquelch() {
+  if (!sdrSquelchSupported) return;
+  saveSetting("sdrSquelchEnabled", sdrSquelchEnabled);
+  saveSetting("sdrSquelchThresholdDb", sdrSquelchThresholdDb);
+  postPath(
+    `/set_sdr_squelch?enabled=${sdrSquelchEnabled ? "true" : "false"}&threshold_db=${encodeURIComponent(sdrSquelchThresholdDb.toFixed(2))}`
+  ).catch(() => {
+  });
+}
+function setSdrSquelch(thresholdDb, enabled, options = {}) {
+  sdrSquelchThresholdDb = clampSdrSquelchDb(thresholdDb);
+  sdrSquelchEnabled = enabled;
+  renderSdrSquelch();
+  if (options.submit !== false) submitSdrSquelch();
+}
+function autoSquelchThresholdDb() {
+  const data = lastSpectrumData || window.lastSpectrumData;
+  if (!data || !isNumericBins(data.bins) || data.bins.length === 0) return null;
+  const noiseDb = estimateNoiseFloorDb(data.bins);
+  if (noiseDb == null || !isFiniteNumber(noiseDb)) return null;
+  return clampSdrSquelchDb(noiseDb + 6);
 }
 function updateSdrSquelchControlVisibility() {
   if (!sdrSquelchWrapEl) return;
   const mode = (modeEl && modeEl.value ? modeEl.value : "").toUpperCase();
   sdrSquelchWrapEl.style.display = sdrSquelchSupported && mode !== "WFM" ? "" : "none";
+  renderSdrSquelch();
 }
 function syncSdrSquelchFromServer(enabled, thresholdDb) {
-  if (!sdrSquelchEl) return;
-  if (document.activeElement === sdrSquelchEl) return;
-  const pct = sdrSquelchServerToPercent(enabled, thresholdDb);
-  syncFromServerSdrSquelch = true;
-  sdrSquelchEl.value = String(pct);
-  updateSdrSquelchPctLabel();
-  syncFromServerSdrSquelch = false;
-  saveSetting("sdrSquelchPct", pct);
+  if (squelchDragPointerId !== null) return;
+  if (sdrSquelchDbEl && document.activeElement === sdrSquelchDbEl) return;
+  sdrSquelchEnabled = enabled;
+  if (isFiniteNumber(thresholdDb)) sdrSquelchThresholdDb = clampSdrSquelchDb(thresholdDb);
+  saveSetting("sdrSquelchEnabled", sdrSquelchEnabled);
+  saveSetting("sdrSquelchThresholdDb", sdrSquelchThresholdDb);
+  renderSdrSquelch();
 }
-function submitSdrSquelchPercent(percent) {
-  if (!sdrSquelchSupported) return;
-  const { enabled, thresholdDb } = sdrSquelchPercentToServer(percent);
-  postPath(
-    `/set_sdr_squelch?enabled=${enabled ? "true" : "false"}&threshold_db=${encodeURIComponent(thresholdDb.toFixed(2))}`
-  ).catch(() => {
+var squelchDragPointerId = null;
+var squelchDragSubmitAt = 0;
+if (sdrSquelchDbEl) {
+  sdrSquelchDbEl.addEventListener("change", () => {
+    setSdrSquelch(Number(sdrSquelchDbEl.value), sdrSquelchEnabled);
+  });
+  sdrSquelchDbEl.addEventListener("blur", () => {
+    renderSdrSquelch();
   });
 }
-if (sdrSquelchEl) {
-  const savedPct = clampSdrSquelchPercent(Number(loadSetting("sdrSquelchPct", 0)));
-  sdrSquelchEl.value = String(savedPct);
-  updateSdrSquelchPctLabel();
-  sdrSquelchEl.addEventListener("input", () => {
-    const pct = clampSdrSquelchPercent(Number(sdrSquelchEl.value));
-    sdrSquelchEl.value = String(pct);
-    updateSdrSquelchPctLabel();
-    saveSetting("sdrSquelchPct", pct);
-    if (!syncFromServerSdrSquelch) {
-      submitSdrSquelchPercent(pct);
-    }
+if (sdrSquelchToggleBtn) {
+  sdrSquelchToggleBtn.addEventListener("click", () => {
+    if (!sdrSquelchSupported) return;
+    setSdrSquelch(sdrSquelchThresholdDb, !sdrSquelchEnabled);
   });
 }
 var sdrSquelchAutoBtn = document.getElementById("sdr-squelch-auto");
 if (sdrSquelchAutoBtn) {
   sdrSquelchAutoBtn.addEventListener("click", () => {
     if (!sdrSquelchSupported) return;
-    let pct = 0;
-    const data = lastSpectrumData || window.lastSpectrumData;
-    if (data && isNumericBins(data.bins) && data.bins.length > 0) {
-      const noiseDb = estimateNoiseFloorDb(data.bins);
-      if (noiseDb != null && isFiniteNumber(noiseDb)) {
-        const thresholdDb = noiseDb + 6;
-        const clamped = Math.max(SDR_SQUELCH_MIN_DB, Math.min(SDR_SQUELCH_MAX_DB, thresholdDb));
-        pct = clampSdrSquelchPercent(
-          (clamped - SDR_SQUELCH_MIN_DB) / (SDR_SQUELCH_MAX_DB - SDR_SQUELCH_MIN_DB) * 100
-        );
-      }
+    const threshold = autoSquelchThresholdDb();
+    if (threshold == null) {
+      showHint("No spectrum to measure the noise from", 1800);
+      return;
     }
-    if (sdrSquelchEl) {
-      sdrSquelchEl.value = String(pct);
-      updateSdrSquelchPctLabel();
-      saveSetting("sdrSquelchPct", pct);
+    setSdrSquelch(threshold, true);
+    showHint(`Squelch ${threshold} dB`, 1500);
+  });
+}
+if (squelchGripEl) {
+  const dbFromClientY = (clientY) => {
+    const canvas = document.getElementById("spectrum-canvas");
+    if (!canvas || !canvas.clientHeight) return sdrSquelchThresholdDb;
+    const rect = canvas.getBoundingClientRect();
+    const frac = 1 - (clientY - rect.top) / rect.height;
+    return clampSdrSquelchDb(spectrumFloor + frac * spectrumRange);
+  };
+  squelchGripEl.addEventListener("pointerdown", (event) => {
+    if (!sdrSquelchSupported) return;
+    squelchDragPointerId = event.pointerId;
+    squelchGripEl.setPointerCapture(event.pointerId);
+    event.preventDefault();
+    event.stopPropagation();
+  });
+  squelchGripEl.addEventListener("pointermove", (event) => {
+    if (squelchDragPointerId !== event.pointerId) return;
+    sdrSquelchThresholdDb = dbFromClientY(event.clientY);
+    renderSdrSquelch();
+    const now = Date.now();
+    if (now - squelchDragSubmitAt > 200) {
+      squelchDragSubmitAt = now;
+      submitSdrSquelch();
     }
-    submitSdrSquelchPercent(pct);
+  });
+  const endDrag = (event) => {
+    if (squelchDragPointerId !== event.pointerId) return;
+    squelchDragPointerId = null;
+    submitSdrSquelch();
+  };
+  squelchGripEl.addEventListener("pointerup", endDrag);
+  squelchGripEl.addEventListener("pointercancel", endDrag);
+  squelchGripEl.addEventListener("keydown", (event) => {
+    const step = event.shiftKey ? 10 : 1;
+    if (event.key === "ArrowUp" || event.key === "ArrowRight") {
+      setSdrSquelch(sdrSquelchThresholdDb + step, sdrSquelchEnabled);
+    } else if (event.key === "ArrowDown" || event.key === "ArrowLeft") {
+      setSdrSquelch(sdrSquelchThresholdDb - step, sdrSquelchEnabled);
+    } else {
+      return;
+    }
+    event.preventDefault();
   });
 }
 if (wfmAudioModeEl) {
@@ -7244,15 +7321,10 @@ function volWheel(slider, pctEl, getGain, storageKey) {
 }
 volWheel(rxVolSlider, rxVolPct, () => rxGainNode, "rxVol");
 volWheel(txVolSlider, txVolPct, () => txGainNode, "txVol");
-if (sdrSquelchEl) {
-  sdrSquelchEl.addEventListener("wheel", (e) => {
-    e.preventDefault();
-    const step = e.deltaY < 0 ? 2 : -2;
-    const next = clampSdrSquelchPercent(Number(sdrSquelchEl.value) + step);
-    sdrSquelchEl.value = String(next);
-    updateSdrSquelchPctLabel();
-    saveSetting("sdrSquelchPct", next);
-    submitSdrSquelchPercent(next);
+if (sdrSquelchDbEl) {
+  sdrSquelchDbEl.addEventListener("wheel", (event) => {
+    event.preventDefault();
+    setSdrSquelch(sdrSquelchThresholdDb + (event.deltaY < 0 ? 1 : -1), sdrSquelchEnabled);
   }, { passive: false });
 }
 requiredElement("copyright-year").textContent = String((/* @__PURE__ */ new Date()).getFullYear());
@@ -8299,6 +8371,7 @@ function drawSpectrum(data) {
   }
   spectrumGl.drawSegments(spectrumTmpGridSegments, cssColorToRgba(pal.spectrumGrid), 1);
   updateSpectrumDbAxis(DB_MIN, DB_MAX, gridStep, H, dpr);
+  positionSquelchLine();
   function hzToX(hz) {
     return (hz - range.visLoHz) / range.visSpanHz * W;
   }
@@ -8927,31 +9000,15 @@ window.addEventListener("keydown", (event) => {
   }
   if (key === "q") {
     event.preventDefault();
-    if (sdrSquelchSupported && sdrSquelchEl) {
-      const current = clampSdrSquelchPercent(Number(sdrSquelchEl.value));
-      let nextPct;
-      if (current > 0) {
-        nextPct = 0;
+    if (sdrSquelchSupported) {
+      if (sdrSquelchEnabled) {
+        setSdrSquelch(sdrSquelchThresholdDb, false);
+        showHint("Squelch off", 1200);
       } else {
-        let auto = 30;
-        const data = lastSpectrumData || window.lastSpectrumData;
-        if (data && isNumericBins(data.bins) && data.bins.length > 0) {
-          const noiseDb = estimateNoiseFloorDb(data.bins);
-          if (noiseDb != null && isFiniteNumber(noiseDb)) {
-            const thresholdDb = noiseDb + 6;
-            const clamped = Math.max(SDR_SQUELCH_MIN_DB, Math.min(SDR_SQUELCH_MAX_DB, thresholdDb));
-            auto = clampSdrSquelchPercent(
-              (clamped - SDR_SQUELCH_MIN_DB) / (SDR_SQUELCH_MAX_DB - SDR_SQUELCH_MIN_DB) * 100
-            );
-          }
-        }
-        nextPct = auto;
+        const threshold = sdrSquelchThresholdDb > SDR_SQUELCH_MIN_DB ? sdrSquelchThresholdDb : autoSquelchThresholdDb() ?? SDR_SQUELCH_MIN_DB + 25;
+        setSdrSquelch(threshold, true);
+        showHint(`Squelch ${clampSdrSquelchDb(threshold)} dB`, 1200);
       }
-      sdrSquelchEl.value = String(nextPct);
-      updateSdrSquelchPctLabel();
-      saveSetting("sdrSquelchPct", nextPct);
-      submitSdrSquelchPercent(nextPct);
-      showHint(nextPct > 0 ? `Squelch ${nextPct}%` : "Squelch Off", 1200);
     } else {
       showHint("Squelch N/A", 1200);
     }
diff --git a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html
index ed043b60..6c3e9fe3 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html
+++ b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html
@@ -142,6 +142,10 @@ SPDX-License-Identifier: GPL-2.0-or-later
           <div id="spectrum-bookmark-side-left" class="spectrum-bookmark-side spectrum-bookmark-side-left" aria-hidden="true"></div>
           <canvas id="spectrum-canvas" tabindex="0" role="img" aria-label="Spectrum display" aria-describedby="spectrum-text-summary"></canvas>
           <p id="spectrum-text-summary" class="visually-hidden">Spectrum data is waiting for the receiver.</p>
+          <div id="spectrum-squelch-line" class="spectrum-squelch-line" style="display:none;" data-state="closed">
+            <span class="spectrum-squelch-grip" id="spectrum-squelch-grip" role="slider" tabindex="0"
+                  aria-label="Squelch threshold" aria-valuemin="-120" aria-valuemax="-30" aria-valuenow="-95">SQL <span id="spectrum-squelch-label">-95</span> dB</span>
+          </div>
           <div id="spectrum-zoom-indicator" aria-hidden="true"></div>
           <div id="spectrum-minimap" aria-hidden="true"><div class="minimap-view"></div></div>
           <div id="spectrum-db-axis" aria-hidden="true"></div>
@@ -411,7 +415,13 @@ SPDX-License-Identifier: GPL-2.0-or-later
                     <button id="tx-audio-btn" type="button">Transmit Audio</button>
                     <label class="vol-label">RX<input type="range" id="rx-vol" min="0" max="100" value="80" class="vol-slider" /><small class="vol-pct" id="rx-vol-pct">80%</small></label>
                     <label class="vol-label">TX<input type="range" id="tx-vol" min="0" max="100" value="80" class="vol-slider" /><small class="vol-pct" id="tx-vol-pct">80%</small></label>
-                    <label class="vol-label" id="sdr-squelch-wrap" style="display:none;">SQL<input type="range" id="sdr-squelch" min="0" max="100" value="0" class="vol-slider" /><small class="vol-pct" id="sdr-squelch-pct">Open</small><button id="sdr-squelch-auto" type="button" class="sql-auto-btn" title="Set squelch to current noise level">Auto</button></label>
+                    <span class="sql-control" id="sdr-squelch-wrap" style="display:none;">
+                      <span class="sql-title">SQL</span>
+                      <span class="sql-state" id="sdr-squelch-state" data-state="off" role="img" aria-label="Squelch state"></span>
+                      <label class="sql-db"><input type="number" id="sdr-squelch-db" min="-120" max="-30" step="1" value="-95" inputmode="numeric" aria-label="Squelch threshold in dB" /><span class="sql-db-unit">dB</span></label>
+                      <button id="sdr-squelch-auto" type="button" class="sql-auto-btn" title="Set the threshold just above the noise floor">Auto</button>
+                      <button id="sdr-squelch-toggle" type="button" class="sql-auto-btn" aria-pressed="false" title="Enable or disable the squelch">Off</button>
+                    </span>
                     <div id="audio-level">
                       <div id="audio-level-fill"></div>
                     </div>
diff --git a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css
index 993a4a86..73caae17 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css
+++ b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css
@@ -1845,6 +1845,106 @@ small { color: var(--text-muted); }
   color: var(--text-muted);
   line-height: 1;
 }
+/* Squelch: a threshold in dB, the unit the spectrum's own axis is labelled in,
+   with a dot showing whether the gate is passing audio right now. The old
+   percentage was a number with nothing on screen to relate it to. */
+.sql-control {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.35rem;
+  color: var(--text-muted);
+  font-size: 0.82rem;
+  white-space: nowrap;
+}
+.sql-title {
+  font-weight: 700;
+  letter-spacing: 0.02em;
+}
+.sql-state {
+  width: 0.5rem;
+  height: 0.5rem;
+  border-radius: 50%;
+  flex-shrink: 0;
+  background: color-mix(in srgb, var(--text-muted) 45%, transparent);
+  transition: background var(--dur-fast) var(--ease-standard),
+              box-shadow var(--dur-fast) var(--ease-standard);
+}
+.sql-state[data-state="open"] {
+  background: var(--status-ok);
+  box-shadow: 0 0 0 0.14rem color-mix(in srgb, var(--status-ok) 25%, transparent);
+}
+.sql-state[data-state="closed"] {
+  background: var(--accent-yellow);
+  box-shadow: 0 0 0 0.14rem color-mix(in srgb, var(--accent-yellow) 22%, transparent);
+}
+.sql-db {
+  display: inline-flex;
+  align-items: baseline;
+  gap: 0.2rem;
+}
+.sql-db input {
+  width: 3.4rem;
+  height: 1.5rem;
+  min-height: 0;
+  padding: 0 0.3rem;
+  font-size: 0.78rem;
+  font-variant-numeric: tabular-nums;
+  text-align: right;
+  border: 1px solid var(--border-light);
+  border-radius: 4px;
+  background: var(--input-bg);
+  color: var(--text);
+}
+.sql-db-unit {
+  font-size: 0.68rem;
+}
+.sql-control button[aria-pressed="true"] {
+  border-color: color-mix(in srgb, var(--accent-green) 55%, var(--border-light));
+  color: var(--accent-text);
+}
+/* The line is the control: it spans the plot at its threshold and carries its
+   own grip, so the level is set where the noise it has to clear is visible. */
+.spectrum-squelch-line {
+  position: absolute;
+  left: 0;
+  right: 0;
+  height: 0;
+  /* Above the overlays that share the plot: the split control sits at the
+     right edge on z-index 9 and would otherwise swallow the grip's pointer. */
+  z-index: 10;
+  border-top: 1px dashed color-mix(in srgb, var(--accent-yellow) 75%, transparent);
+  pointer-events: none;
+}
+.spectrum-squelch-line[data-state="open"] {
+  border-top-color: color-mix(in srgb, var(--status-ok) 80%, transparent);
+}
+.spectrum-squelch-grip {
+  position: absolute;
+  /* Clear of the split control's column so the two never sit on top of each
+     other, whatever height the threshold is at. */
+  right: 3.6rem;
+  top: -0.72rem;
+  padding: 0.05rem 0.35rem;
+  border-radius: 3px;
+  border: 1px solid color-mix(in srgb, var(--accent-yellow) 60%, var(--border-light));
+  background: color-mix(in srgb, var(--card-bg) 88%, transparent);
+  color: var(--text);
+  font-size: 0.62rem;
+  font-weight: 700;
+  font-variant-numeric: tabular-nums;
+  line-height: 1.3;
+  cursor: ns-resize;
+  pointer-events: auto;
+  user-select: none;
+  touch-action: none;
+}
+.spectrum-squelch-line[data-state="open"] .spectrum-squelch-grip {
+  border-color: color-mix(in srgb, var(--status-ok) 60%, var(--border-light));
+}
+.spectrum-squelch-grip:focus-visible {
+  outline: 2px solid var(--accent-text);
+  outline-offset: 1px;
+}
 .sql-auto-btn {
   font-size: 0.68rem;
   padding: 0 5px;
diff --git a/src/trx-client/trx-frontend/trx-frontend-http/frontend/src/app.ts b/src/trx-client/trx-frontend/trx-frontend-http/frontend/src/app.ts
index e565561d..6950595a 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/frontend/src/app.ts
+++ b/src/trx-client/trx-frontend/trx-frontend-http/frontend/src/app.ts
@@ -946,6 +946,8 @@ function formatSigStrength(dbm: number | null) {
 }
 
 function refreshSigStrengthDisplay() {
+  // The squelch indicator reads the same meter, so it follows it here.
+  renderSdrSquelch();
   if (!sigStrengthEl) return;
   sigStrengthEl.innerHTML = formatSigStrength(sigLastDbm);
 }
@@ -5151,11 +5153,14 @@ const modeControlsRow = document.getElementById("mode-controls-row");
 const samStereoWidthEl = document.getElementById("sam-stereo-width") as HTMLInputElement | null;
 const samCarrierSyncEl = document.getElementById("sam-carrier-sync") as HTMLSelectElement | null;
 const sdrSquelchWrapEl = document.getElementById("sdr-squelch-wrap");
-const sdrSquelchEl = document.getElementById("sdr-squelch") as HTMLInputElement | null;
-const sdrSquelchPctEl = document.getElementById("sdr-squelch-pct");
+const sdrSquelchDbEl = document.getElementById("sdr-squelch-db") as HTMLInputElement | null;
+const sdrSquelchStateEl = document.getElementById("sdr-squelch-state");
+const sdrSquelchToggleBtn = document.getElementById("sdr-squelch-toggle") as HTMLButtonElement | null;
+const squelchLineEl = document.getElementById("spectrum-squelch-line");
+const squelchGripEl = document.getElementById("spectrum-squelch-grip");
+const squelchLabelEl = document.getElementById("spectrum-squelch-label");
 const SDR_SQUELCH_MIN_DB = -120;
 const SDR_SQUELCH_MAX_DB = -30;
-let syncFromServerSdrSquelch = false;
 const sdrNbWrapEl = document.getElementById("sdr-nb-wrap");
 const sdrNbEnabledEl = document.getElementById("sdr-nb-enabled") as HTMLInputElement | null;
 const sdrNbThresholdControlsEl = document.getElementById("sdr-nb-threshold-controls");
@@ -5255,71 +5260,131 @@ function normalizeWfmDenoiseLevel(value: unknown) {
   return "auto";
 }
 
-function clampSdrSquelchPercent(value: number) {
-  if (!isFiniteNumber(value)) return 0;
-  return Math.max(0, Math.min(100, Math.round(value)));
+// The threshold is held in dB, the scale the spectrum axis and the S-meter are
+// labelled in and the one the server compares against. It used to be a
+// percentage over that range, which left the operator no way to relate the
+// control to anything on screen — and 0% doubled as "disabled", so turning the
+// squelch off to listen threw the setting away.
+let sdrSquelchEnabled: boolean = loadSetting("sdrSquelchEnabled", false);
+let sdrSquelchThresholdDb = clampSdrSquelchDb(Number(loadSetting("sdrSquelchThresholdDb", -95)));
+
+function clampSdrSquelchDb(value: number) {
+  if (!isFiniteNumber(value)) return SDR_SQUELCH_MIN_DB;
+  return Math.max(SDR_SQUELCH_MIN_DB, Math.min(SDR_SQUELCH_MAX_DB, Math.round(value)));
 }
 
-function sdrSquelchPercentToServer(percent: number) {
-  const pct = clampSdrSquelchPercent(percent);
-  if (pct <= 0) {
-    return { enabled: false, thresholdDb: SDR_SQUELCH_MIN_DB };
+/** Passing right now, as far as the meter can tell: the same comparison the
+ *  DSP makes, against the same number it reports. */
+function sdrSquelchIsPassing() {
+  if (!sdrSquelchEnabled) return true;
+  if (!isFiniteNumber(sigLastDbm)) return false;
+  return sigLastDbm >= sdrSquelchThresholdDb;
+}
+
+function renderSdrSquelch() {
+  if (sdrSquelchDbEl && document.activeElement !== sdrSquelchDbEl) {
+    sdrSquelchDbEl.value = String(sdrSquelchThresholdDb);
   }
-  const ratio = pct / 100;
-  const thresholdDb = SDR_SQUELCH_MIN_DB + ratio * (SDR_SQUELCH_MAX_DB - SDR_SQUELCH_MIN_DB);
-  return { enabled: true, thresholdDb };
+  if (sdrSquelchDbEl) sdrSquelchDbEl.disabled = !sdrSquelchSupported;
+  if (sdrSquelchToggleBtn) {
+    sdrSquelchToggleBtn.textContent = sdrSquelchEnabled ? "On" : "Off";
+    sdrSquelchToggleBtn.setAttribute("aria-pressed", String(sdrSquelchEnabled));
+  }
+  const state = !sdrSquelchEnabled ? "off" : (sdrSquelchIsPassing() ? "open" : "closed");
+  if (sdrSquelchStateEl) {
+    sdrSquelchStateEl.dataset.state = state;
+    sdrSquelchStateEl.setAttribute(
+      "aria-label",
+      state === "off" ? "Squelch off" : (state === "open" ? "Squelch open" : "Squelch closed"),
+    );
+  }
+  if (squelchLabelEl) squelchLabelEl.textContent = String(sdrSquelchThresholdDb);
+  if (squelchGripEl) squelchGripEl.setAttribute("aria-valuenow", String(sdrSquelchThresholdDb));
+  if (squelchLineEl) squelchLineEl.dataset.state = state === "open" ? "open" : "closed";
+  positionSquelchLine();
 }
 
-function sdrSquelchServerToPercent(enabled: boolean, thresholdDb: number | null) {
-  if (!enabled) return 0;
-  if (!isFiniteNumber(thresholdDb)) return 0;
-  const ratio = (thresholdDb - SDR_SQUELCH_MIN_DB) / (SDR_SQUELCH_MAX_DB - SDR_SQUELCH_MIN_DB);
-  return clampSdrSquelchPercent(ratio * 100);
+/** Places the line at its threshold on the spectrum's dB axis. */
+function positionSquelchLine() {
+  if (!squelchLineEl) return;
+  const mode = (modeEl && modeEl.value ? modeEl.value : "").toUpperCase();
+  const canvas = document.getElementById("spectrum-canvas");
+  const visible = sdrSquelchSupported && sdrSquelchEnabled && mode !== "WFM"
+    && !!canvas && canvas.clientHeight > 0
+    && getComputedStyle(requiredElement("spectrum-panel")).display !== "none";
+  if (!visible) {
+    squelchLineEl.style.display = "none";
+    return;
+  }
+  const dbMin = spectrumFloor;
+  const dbMax = spectrumFloor + spectrumRange;
+  // Pinned to the plot edge when the threshold sits outside the visible dB
+  // window rather than hidden: the grip is how it gets dragged back, and the
+  // label still reads the real value.
+  const frac = Math.max(0, Math.min(1, (sdrSquelchThresholdDb - dbMin) / Math.max(1, dbMax - dbMin)));
+  squelchLineEl.style.display = "";
+  squelchLineEl.style.top = `${canvas.offsetTop + canvas.clientHeight * (1 - frac)}px`;
 }
 
-function updateSdrSquelchPctLabel() {
-  if (!sdrSquelchEl || !sdrSquelchPctEl) return;
-  const pct = clampSdrSquelchPercent(Number(sdrSquelchEl.value));
-  sdrSquelchPctEl.textContent = pct <= 0 ? "Open" : `${pct}%`;
+function submitSdrSquelch() {
+  if (!sdrSquelchSupported) return;
+  saveSetting("sdrSquelchEnabled", sdrSquelchEnabled);
+  saveSetting("sdrSquelchThresholdDb", sdrSquelchThresholdDb);
+  postPath(
+    `/set_sdr_squelch?enabled=${sdrSquelchEnabled ? "true" : "false"}`
+    + `&threshold_db=${encodeURIComponent(sdrSquelchThresholdDb.toFixed(2))}`,
+  ).catch(() => {});
+}
+
+function setSdrSquelch(thresholdDb: number, enabled: boolean, options: { submit?: boolean } = {}) {
+  sdrSquelchThresholdDb = clampSdrSquelchDb(thresholdDb);
+  sdrSquelchEnabled = enabled;
+  renderSdrSquelch();
+  if (options.submit !== false) submitSdrSquelch();
+}
+
+/** Just above the noise, which is the level the gate has to clear. */
+function autoSquelchThresholdDb(): number | null {
+  const data = lastSpectrumData || window.lastSpectrumData;
+  if (!data || !isBinsArray(data.bins) || data.bins.length === 0) return null;
+  const noiseDb = estimateNoiseFloorDb(data.bins);
+  if (noiseDb == null || !isFiniteNumber(noiseDb)) return null;
+  return clampSdrSquelchDb(noiseDb + 6);
 }
 
 function updateSdrSquelchControlVisibility() {
   if (!sdrSquelchWrapEl) return;
   const mode = (modeEl && modeEl.value ? modeEl.value : "").toUpperCase();
   sdrSquelchWrapEl.style.display = sdrSquelchSupported && mode !== "WFM" ? "" : "none";
+  renderSdrSquelch();
 }
 
 function syncSdrSquelchFromServer(enabled: boolean, thresholdDb: number | null) {
-  if (!sdrSquelchEl) return;
-  if (document.activeElement === sdrSquelchEl) return;
-  const pct = sdrSquelchServerToPercent(enabled, thresholdDb);
-  syncFromServerSdrSquelch = true;
-  sdrSquelchEl.value = String(pct);
-  updateSdrSquelchPctLabel();
-  syncFromServerSdrSquelch = false;
-  saveSetting("sdrSquelchPct", pct);
+  // Not while the operator is on the control: dragging the line or typing a
+  // level would fight the echo of the value the server last confirmed.
+  if (squelchDragPointerId !== null) return;
+  if (sdrSquelchDbEl && document.activeElement === sdrSquelchDbEl) return;
+  sdrSquelchEnabled = enabled;
+  if (isFiniteNumber(thresholdDb)) sdrSquelchThresholdDb = clampSdrSquelchDb(thresholdDb);
+  saveSetting("sdrSquelchEnabled", sdrSquelchEnabled);
+  saveSetting("sdrSquelchThresholdDb", sdrSquelchThresholdDb);
+  renderSdrSquelch();
 }
 
-function submitSdrSquelchPercent(percent: number) {
-  if (!sdrSquelchSupported) return;
-  const { enabled, thresholdDb } = sdrSquelchPercentToServer(percent);
-  postPath(
-    `/set_sdr_squelch?enabled=${enabled ? "true" : "false"}&threshold_db=${encodeURIComponent(thresholdDb.toFixed(2))}`,
-  ).catch(() => {});
+let squelchDragPointerId: number | null = null;
+let squelchDragSubmitAt = 0;
+
+if (sdrSquelchDbEl) {
+  sdrSquelchDbEl.addEventListener("change", () => {
+    setSdrSquelch(Number(sdrSquelchDbEl.value), sdrSquelchEnabled);
+  });
+  sdrSquelchDbEl.addEventListener("blur", () => { renderSdrSquelch(); });
 }
 
-if (sdrSquelchEl) {
-  const savedPct = clampSdrSquelchPercent(Number(loadSetting("sdrSquelchPct", 0)));
-  sdrSquelchEl.value = String(savedPct);
-  updateSdrSquelchPctLabel();
-  sdrSquelchEl.addEventListener("input", () => {
-    const pct = clampSdrSquelchPercent(Number(sdrSquelchEl.value));
-    sdrSquelchEl.value = String(pct);
-    updateSdrSquelchPctLabel();
-    saveSetting("sdrSquelchPct", pct);
-    if (!syncFromServerSdrSquelch) {
-      submitSdrSquelchPercent(pct);
-    }
+if (sdrSquelchToggleBtn) {
+  sdrSquelchToggleBtn.addEventListener("click", () => {
+    if (!sdrSquelchSupported) return;
+    setSdrSquelch(sdrSquelchThresholdDb, !sdrSquelchEnabled);
   });
 }
 
@@ -5327,25 +5392,60 @@ const sdrSquelchAutoBtn = document.getElementById("sdr-squelch-auto") as HTMLBut
 if (sdrSquelchAutoBtn) {
   sdrSquelchAutoBtn.addEventListener("click", () => {
     if (!sdrSquelchSupported) return;
-    let pct = 0; // default: Off
-    const data = lastSpectrumData || window.lastSpectrumData;
-    if (data && isBinsArray(data.bins) && data.bins.length > 0) {
-      const noiseDb = estimateNoiseFloorDb(data.bins);
-      if (noiseDb != null && isFiniteNumber(noiseDb)) {
-        // Set threshold slightly above noise floor so squelch closes on noise
-        const thresholdDb = noiseDb + 6;
-        const clamped = Math.max(SDR_SQUELCH_MIN_DB, Math.min(SDR_SQUELCH_MAX_DB, thresholdDb));
-        pct = clampSdrSquelchPercent(
-          ((clamped - SDR_SQUELCH_MIN_DB) / (SDR_SQUELCH_MAX_DB - SDR_SQUELCH_MIN_DB)) * 100,
-        );
-      }
+    const threshold = autoSquelchThresholdDb();
+    if (threshold == null) {
+      showHint("No spectrum to measure the noise from", 1800);
+      return;
     }
-    if (sdrSquelchEl) {
-      sdrSquelchEl.value = String(pct);
-      updateSdrSquelchPctLabel();
-      saveSetting("sdrSquelchPct", pct);
+    setSdrSquelch(threshold, true);
+    showHint(`Squelch ${threshold} dB`, 1500);
+  });
+}
+
+// Dragging the line, the same gesture as the bandwidth edges. Submits are
+// throttled so the gate follows the drag by ear without a request per pixel.
+if (squelchGripEl) {
+  const dbFromClientY = (clientY: number) => {
+    const canvas = document.getElementById("spectrum-canvas");
+    if (!canvas || !canvas.clientHeight) return sdrSquelchThresholdDb;
+    const rect = canvas.getBoundingClientRect();
+    const frac = 1 - (clientY - rect.top) / rect.height;
+    return clampSdrSquelchDb(spectrumFloor + frac * spectrumRange);
+  };
+  squelchGripEl.addEventListener("pointerdown", (event) => {
+    if (!sdrSquelchSupported) return;
+    squelchDragPointerId = event.pointerId;
+    squelchGripEl.setPointerCapture(event.pointerId);
+    event.preventDefault();
+    event.stopPropagation();
+  });
+  squelchGripEl.addEventListener("pointermove", (event) => {
+    if (squelchDragPointerId !== event.pointerId) return;
+    sdrSquelchThresholdDb = dbFromClientY(event.clientY);
+    renderSdrSquelch();
+    const now = Date.now();
+    if (now - squelchDragSubmitAt > 200) {
+      squelchDragSubmitAt = now;
+      submitSdrSquelch();
     }
-    submitSdrSquelchPercent(pct);
+  });
+  const endDrag = (event: PointerEvent) => {
+    if (squelchDragPointerId !== event.pointerId) return;
+    squelchDragPointerId = null;
+    submitSdrSquelch();
+  };
+  squelchGripEl.addEventListener("pointerup", endDrag);
+  squelchGripEl.addEventListener("pointercancel", endDrag);
+  squelchGripEl.addEventListener("keydown", (event) => {
+    const step = event.shiftKey ? 10 : 1;
+    if (event.key === "ArrowUp" || event.key === "ArrowRight") {
+      setSdrSquelch(sdrSquelchThresholdDb + step, sdrSquelchEnabled);
+    } else if (event.key === "ArrowDown" || event.key === "ArrowLeft") {
+      setSdrSquelch(sdrSquelchThresholdDb - step, sdrSquelchEnabled);
+    } else {
+      return;
+    }
+    event.preventDefault();
   });
 }
 
@@ -6176,15 +6276,10 @@ function volWheel(slider: HTMLInputElement, pctEl: HTMLElement, getGain: () => G
 }
 volWheel(rxVolSlider, rxVolPct, () => rxGainNode, "rxVol");
 volWheel(txVolSlider, txVolPct, () => txGainNode, "txVol");
-if (sdrSquelchEl) {
-  sdrSquelchEl.addEventListener("wheel", (e) => {
-    e.preventDefault();
-    const step = e.deltaY < 0 ? 2 : -2;
-    const next = clampSdrSquelchPercent(Number(sdrSquelchEl.value) + step);
-    sdrSquelchEl.value = String(next);
-    updateSdrSquelchPctLabel();
-    saveSetting("sdrSquelchPct", next);
-    submitSdrSquelchPercent(next);
+if (sdrSquelchDbEl) {
+  sdrSquelchDbEl.addEventListener("wheel", (event) => {
+    event.preventDefault();
+    setSdrSquelch(sdrSquelchThresholdDb + (event.deltaY < 0 ? 1 : -1), sdrSquelchEnabled);
   }, { passive: false });
 }
 
@@ -7398,6 +7493,9 @@ function drawSpectrum(data: SpectrumFrame) {
   }
   spectrumGl.drawSegments(spectrumTmpGridSegments, cssColorToRgba(pal.spectrumGrid), 1);
   updateSpectrumDbAxis(DB_MIN, DB_MAX, gridStep, H, dpr);
+  // The squelch line rides the same axis: reposition it whenever the axis or
+  // the plot geometry moves under it.
+  positionSquelchLine();
 
   function hzToX(hz: number) {
     return ((hz - range.visLoHz) / range.visSpanHz) * W;
@@ -8125,35 +8223,21 @@ window.addEventListener("keydown", (event) => {
     return;
   }
 
-  // Q — toggle squelch (cycle 0 → auto → 0)
+  // Q — gate on or off, keeping the threshold. Picks one off the noise floor
+  // the first time, when there is nothing to keep.
   if (key === "q") {
     event.preventDefault();
-    if (sdrSquelchSupported && sdrSquelchEl) {
-      const current = clampSdrSquelchPercent(Number(sdrSquelchEl.value));
-      let nextPct;
-      if (current > 0) {
-        nextPct = 0; // turn off
+    if (sdrSquelchSupported) {
+      if (sdrSquelchEnabled) {
+        setSdrSquelch(sdrSquelchThresholdDb, false);
+        showHint("Squelch off", 1200);
       } else {
-        // Auto: estimate from noise floor
-        let auto = 30;
-        const data = lastSpectrumData || window.lastSpectrumData;
-        if (data && isBinsArray(data.bins) && data.bins.length > 0) {
-          const noiseDb = estimateNoiseFloorDb(data.bins);
-          if (noiseDb != null && isFiniteNumber(noiseDb)) {
-            const thresholdDb = noiseDb + 6;
-            const clamped = Math.max(SDR_SQUELCH_MIN_DB, Math.min(SDR_SQUELCH_MAX_DB, thresholdDb));
-            auto = clampSdrSquelchPercent(
-              ((clamped - SDR_SQUELCH_MIN_DB) / (SDR_SQUELCH_MAX_DB - SDR_SQUELCH_MIN_DB)) * 100,
-            );
-          }
-        }
-        nextPct = auto;
+        const threshold = sdrSquelchThresholdDb > SDR_SQUELCH_MIN_DB
+          ? sdrSquelchThresholdDb
+          : (autoSquelchThresholdDb() ?? SDR_SQUELCH_MIN_DB + 25);
+        setSdrSquelch(threshold, true);
+        showHint(`Squelch ${clampSdrSquelchDb(threshold)} dB`, 1200);
       }
-      sdrSquelchEl.value = String(nextPct);
-      updateSdrSquelchPctLabel();
-      saveSetting("sdrSquelchPct", nextPct);
-      submitSdrSquelchPercent(nextPct);
-      showHint(nextPct > 0 ? `Squelch ${nextPct}%` : "Squelch Off", 1200);
     } else {
       showHint("Squelch N/A", 1200);
     }
diff --git a/src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/spectrum-layout.mjs b/src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/spectrum-layout.mjs
index de6a39a1..a1c0a1d3 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/spectrum-layout.mjs
+++ b/src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/spectrum-layout.mjs
@@ -12,7 +12,7 @@ import assert from "node:assert/strict";
 import { chromium } from "playwright-core";
 import { startBrowser, startWebFixture } from "./web-fixture.mjs";
 
-/* global document */
+/* global document, getComputedStyle */
 
 const BOOKMARKS = [
   { id: "b1", name: "40m FT8", freq_hz: 7074000, mode: "DIG", category: "Digital", comment: "", locator: "" },
@@ -120,6 +120,67 @@ try {
   assert.equal(hits.chip, "chip", `chip is not clickable, hit ${hits.chip}`);
   assert.equal(hits.besideChip, "overview-canvas", `rail swallows events, hit ${hits.besideChip}`);
 
+  // Squelch: the threshold is in the dB the spectrum axis is labelled in, so the
+  // line is the control. It used to be a percentage on a slider in the audio
+  // row, with nothing on screen to relate the number to.
+  await page.locator("summary", { hasText: "Audio controls" }).click();
+  await page.locator("#sdr-squelch-toggle").click();
+  // Auto parks it just above the noise, which is mid-axis and leaves room to
+  // drag in either direction.
+  await page.locator("#sdr-squelch-auto").click();
+  await page.waitForTimeout(300);
+  const squelchOn = await page.evaluate(() => {
+    const line = document.getElementById("spectrum-squelch-line");
+    return {
+      shown: getComputedStyle(line).display !== "none",
+      db: Number(document.getElementById("sdr-squelch-db").value),
+      label: Number(document.getElementById("spectrum-squelch-label").textContent),
+      toggle: document.getElementById("sdr-squelch-toggle").textContent,
+      top: Math.round(line.getBoundingClientRect().top),
+    };
+  });
+  assert.equal(squelchOn.shown, true, "the threshold line did not appear with the squelch on");
+  assert.equal(squelchOn.toggle, "On", "the toggle did not follow the squelch state");
+  assert.equal(squelchOn.label, squelchOn.db, "the line and the readout disagree on the threshold");
+
+  // Dragging the line down lowers the threshold and tells the server.
+  const submitted = [];
+  page.on("request", (request) => {
+    if (request.url().includes("/set_sdr_squelch")) {
+      submitted.push(Number(new URL(request.url()).searchParams.get("threshold_db")));
+    }
+  });
+  const grip = await page.locator("#spectrum-squelch-grip").boundingBox();
+  await page.mouse.move(grip.x + grip.width / 2, grip.y + grip.height / 2);
+  await page.mouse.down();
+  await page.mouse.move(grip.x + grip.width / 2, grip.y + grip.height / 2 + 60, { steps: 8 });
+  await page.mouse.up();
+  await page.waitForTimeout(400);
+  const dragged = await page.evaluate(() => ({
+    db: Number(document.getElementById("sdr-squelch-db").value),
+    label: Number(document.getElementById("spectrum-squelch-label").textContent),
+    top: Math.round(document.getElementById("spectrum-squelch-line").getBoundingClientRect().top),
+  }));
+  assert.ok(dragged.db < squelchOn.db,
+    `dragging down left the threshold at ${dragged.db} dB (was ${squelchOn.db})`);
+  assert.equal(dragged.label, dragged.db, "the line label did not follow the drag");
+  assert.ok(dragged.top > squelchOn.top, "the line did not move with the drag");
+  assert.ok(submitted.includes(dragged.db),
+    `the server was never told about ${dragged.db} dB (saw ${JSON.stringify(submitted)})`);
+
+  // Turning it off leaves the threshold alone — the old control conflated the
+  // two, so dropping to zero to listen threw the setting away.
+  await page.locator("#sdr-squelch-toggle").click();
+  await page.waitForTimeout(300);
+  const squelchOff = await page.evaluate(() => ({
+    db: Number(document.getElementById("sdr-squelch-db").value),
+    shown: getComputedStyle(document.getElementById("spectrum-squelch-line")).display !== "none",
+    dot: document.getElementById("sdr-squelch-state").dataset.state,
+  }));
+  assert.equal(squelchOff.db, dragged.db, "turning the squelch off discarded the threshold");
+  assert.equal(squelchOff.shown, false, "the line stayed up with the squelch off");
+  assert.equal(squelchOff.dot, "off", "the indicator did not follow the squelch off");
+
   assert.deepEqual(runtimeErrors, []);
 } finally {
   await browser.close();
diff --git a/src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/web-fixture.mjs b/src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/web-fixture.mjs
index 276ac0cd..5afeccf3 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/web-fixture.mjs
+++ b/src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/web-fixture.mjs
@@ -111,7 +111,17 @@ export async function startWebFixture({
         signal_meter: spectrum,
       },
     },
-    status: { freq: { hz: 100_000_000 }, mode: "FM", tx_en: false, vfo: null, tx: null, rx: null, lock: null },
+    status: { freq: { hz: 100_000_000 }, mode: "FM", tx_en: false, vfo: null, tx: null, rx: { sig: -70 }, lock: null },
+    // Reported only by SDR backends, and what makes the client show the
+    // squelch control at all.
+    filter: spectrum
+      ? {
+        bandwidth_hz: 12_000,
+        sdr_squelch_enabled: false,
+        sdr_squelch_threshold_db: -95,
+        sdr_agc_enabled: false,
+      }
+      : null,
     band: null,
     enabled: true,
     initialized: true,
@@ -184,8 +194,11 @@ export async function startWebFixture({
       response.end(JSON.stringify(jsonRoutes.get(url.pathname)));
       return;
     }
+    // 200 means "audio is configured": the client hides the whole audio row —
+    // and the squelch control with it — when this 404s.
     if (url.pathname === "/audio") {
-      response.writeHead(404).end();
+      response.writeHead(200, { "content-type": "application/json" });
+      response.end(JSON.stringify({ sample_rate: 48_000, channels: 1 }));
       return;
     }
     if (spectrum && url.pathname === "/spectrum") {