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 2759354e..ce058897 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
@@ -3729,10 +3729,19 @@ function visibleBandwidthSpecs(freqHz = lastFreqHz, mode = modeEl ? modeEl.value
   }
   return [{ centerHz: freqHz, widthHz: currentBandwidthHz }];
 }
+function digSidebandDirection() {
+  if (sdrDigSidebandPolicy === "usb") return 1;
+  if (sdrDigSidebandPolicy === "lsb") return -1;
+  if (typeof lastFreqHz === "number" && isFiniteNumber(lastFreqHz)) {
+    return lastFreqHz >= DIG_AUTO_SIDEBAND_THRESHOLD_HZ ? 1 : -1;
+  }
+  return 1;
+}
 function sidebandDirectionForMode(mode = modeEl ? modeEl.value : "") {
   const modeUpper = String(mode || "").toUpperCase();
   if (modeUpper === "LSB" || modeUpper === "CWR") return -1;
-  if (modeUpper === "USB" || modeUpper === "CW" || modeUpper === "DIG") return 1;
+  if (modeUpper === "DIG") return sdrDigSidebandSupported ? digSidebandDirection() : 1;
+  if (modeUpper === "USB" || modeUpper === "CW") return 1;
   return 0;
 }
 function displaySpanForBandwidthSpec(spec, mode = modeEl ? modeEl.value : "") {
@@ -4760,10 +4769,15 @@ function render(update) {
     }
     if (typeof update.filter.sdr_dig_sideband === "string") {
       sdrDigSidebandSupported = true;
+      const prevPolicy = sdrDigSidebandPolicy;
+      sdrDigSidebandPolicy = update.filter.sdr_dig_sideband;
       if (sdrDigSidebandEl && document.activeElement !== sdrDigSidebandEl) {
         sdrDigSidebandEl.value = update.filter.sdr_dig_sideband;
       }
       updateWfmControls();
+      if (prevPolicy !== sdrDigSidebandPolicy && lastSpectrumData) {
+        scheduleSpectrumDraw();
+      }
     }
   }
   if (typeof update.show_sdr_gain_control === "boolean") {
@@ -6634,6 +6648,8 @@ var sdrNbSupported = false;
 var sdrDigSidebandWrapEl = document.getElementById("sdr-dig-sideband-wrap");
 var sdrDigSidebandEl = document.getElementById("sdr-dig-sideband");
 var sdrDigSidebandSupported = false;
+var sdrDigSidebandPolicy = "auto";
+var DIG_AUTO_SIDEBAND_THRESHOLD_HZ = 1e7;
 fetch("/audio", { method: "GET" }).then((r) => {
   if (r.status === 404) audioRow.style.display = "none";
 }).catch(() => {
@@ -7033,6 +7049,8 @@ function submitSdrDigSideband() {
   if (!sdrDigSidebandSupported || !sdrDigSidebandEl) return;
   const policy = sdrDigSidebandEl.value || "auto";
   if (policy !== "auto" && policy !== "usb" && policy !== "lsb") return;
+  sdrDigSidebandPolicy = policy;
+  if (lastSpectrumData) scheduleSpectrumDraw();
   postPath(`/set_sdr_dig_sideband?policy=${encodeURIComponent(policy)}`).catch(() => {
   });
 }
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 33ce2e05..800a4cee 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
@@ -2450,10 +2450,26 @@ function visibleBandwidthSpecs(freqHz: number | null = lastFreqHz, mode = modeEl
   return [{ centerHz: freqHz, widthHz: currentBandwidthHz }];
 }
 
+// Resolve the DIG passband direction from the current policy and dial
+// frequency, mirroring the backend's demodulator resolution so the spectrum
+// overlay lands on the same sideband that is actually being demodulated.
+function digSidebandDirection() {
+  if (sdrDigSidebandPolicy === "usb") return 1;
+  if (sdrDigSidebandPolicy === "lsb") return -1;
+  // "auto": USB at/above the threshold, LSB below.
+  if (typeof lastFreqHz === "number" && isFiniteNumber(lastFreqHz)) {
+    return lastFreqHz >= DIG_AUTO_SIDEBAND_THRESHOLD_HZ ? 1 : -1;
+  }
+  return 1;
+}
+
 function sidebandDirectionForMode(mode = modeEl ? modeEl.value : "") {
   const modeUpper = String(mode || "").toUpperCase();
   if (modeUpper === "LSB" || modeUpper === "CWR") return -1;
-  if (modeUpper === "USB" || modeUpper === "CW" || modeUpper === "DIG") return 1;
+  // On SDR the DIG sideband is configurable; resolve it. On other backends
+  // keep the historical upper-sideband overlay.
+  if (modeUpper === "DIG") return sdrDigSidebandSupported ? digSidebandDirection() : 1;
+  if (modeUpper === "USB" || modeUpper === "CW") return 1;
   return 0;
 }
 
@@ -3683,10 +3699,16 @@ function render(update: AppUpdate) {
     }
     if (typeof update.filter.sdr_dig_sideband === "string") {
       sdrDigSidebandSupported = true;
+      const prevPolicy = sdrDigSidebandPolicy;
+      sdrDigSidebandPolicy = update.filter.sdr_dig_sideband;
       if (sdrDigSidebandEl && document.activeElement !== sdrDigSidebandEl) {
         sdrDigSidebandEl.value = update.filter.sdr_dig_sideband;
       }
       updateWfmControls();
+      // Repaint the passband overlay if the DIG sideband just changed.
+      if (prevPolicy !== sdrDigSidebandPolicy && lastSpectrumData) {
+        scheduleSpectrumDraw();
+      }
     }
   }
   if (typeof update.show_sdr_gain_control === "boolean") {
@@ -5621,6 +5643,11 @@ let sdrNbSupported = false;
 const sdrDigSidebandWrapEl = document.getElementById("sdr-dig-sideband-wrap");
 const sdrDigSidebandEl = document.getElementById("sdr-dig-sideband") as HTMLSelectElement | null;
 let sdrDigSidebandSupported = false;
+// Current DIG sideband policy ("auto" | "usb" | "lsb"), mirrored from server
+// filter state. Drives the spectrum passband overlay direction for DIG.
+let sdrDigSidebandPolicy = "auto";
+// Matches DigSidebandPolicy::AUTO_THRESHOLD_HZ on the backend.
+const DIG_AUTO_SIDEBAND_THRESHOLD_HZ = 10_000_000;
 
 // Hide audio row if audio is not configured on the server
 fetch("/audio", { method: "GET" }).then((r) => {
@@ -6076,6 +6103,10 @@ function submitSdrDigSideband() {
   if (!sdrDigSidebandSupported || !sdrDigSidebandEl) return;
   const policy = sdrDigSidebandEl.value || "auto";
   if (policy !== "auto" && policy !== "usb" && policy !== "lsb") return;
+  // Optimistically move the passband overlay to the chosen sideband so the
+  // display responds instantly, before the server round-trip confirms it.
+  sdrDigSidebandPolicy = policy;
+  if (lastSpectrumData) scheduleSpectrumDraw();
   postPath(`/set_sdr_dig_sideband?policy=${encodeURIComponent(policy)}`).catch(() => {});
 }
 if (sdrDigSidebandEl) {