[feat](trx-rs): configurable DIG sideband for SDR (auto/USB/LSB)

DIG has no inherent sideband; on the SDR backend it was always demodulated
as USB. Make it resolve to USB or LSB via a policy that defaults to the
amateur SSB/data convention (USB at/above 10 MHz, LSB below) and can be
overridden globally from the advanced radio controls or per-bookmark.

Design: the logical DIG mode is kept in RigState (display, decoder gating)
while the SDR pipeline is handed a concrete USB/LSB demodulator resolved from
(policy, dial frequency). Resolution happens at the boundary — the rig for
the primary channel and the virtual-channel manager for vchans — so the hot
DSP/demod path is untouched. The resolved sideband is only re-pushed when it
actually changes (e.g. tuning DIG/Auto across 10 MHz), keeping ordinary
tuning glitch-free.

Core/protocol:
- New `DigSidebandPolicy { Auto, Usb, Lsb }` with `resolve(freq)` and an
  `effective_demod_mode()` helper (trx-core), re-exported at the crate root.
- `RigCommand::SetSdrDigSideband`, `RigSdr::set_sdr_dig_sideband`, and a
  `RigFilterState.sdr_dig_sideband` field for state sync; wired through the
  ClientCommand mapping.

Config: `[rig.sdr] dig_sideband = "auto"` (regenerated trx-rs.toml.example).

SDR backend: the vchan manager owns the shared policy (atomic); the rig
applies it to the primary channel and, on `set_sdr_dig_sideband`, re-resolves
all DIG virtual channels.

Frontend: a mode-gated "DIG sideband" selector in the SDR advanced controls
(POST /set_sdr_dig_sideband), reflecting server state; bookmarks gain an
optional `dig_sideband` field (form selector shown only for DIG) that, on
apply, sets the global policy before switching to DIG. The scheduler honours
it for automated bookmark activation too.

Tests: policy resolution / effective-mode / u8+parse round-trips (trx-core);
a vchan integration test asserting a DIG channel resolves to LSB below
10 MHz, flips with the policy, and still lists as DIG.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UiK871ht2uPFBHtMbxy3wD
Signed-off-by: Stan Grams <sjg@haxx.space>

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

@@ -4758,6 +4758,13 @@ function render(update) {
         }
       }
     }
+    if (typeof update.filter.sdr_dig_sideband === "string") {
+      sdrDigSidebandSupported = true;
+      if (sdrDigSidebandEl && document.activeElement !== sdrDigSidebandEl) {
+        sdrDigSidebandEl.value = update.filter.sdr_dig_sideband;
+      }
+      updateWfmControls();
+    }
   }
   if (typeof update.show_sdr_gain_control === "boolean") {
     if (sdrSettingsRowEl) sdrSettingsRowEl.style.display = update.show_sdr_gain_control ? "" : "none";
@@ -6624,6 +6631,9 @@ var sdrNbThresholdControlsEl = document.getElementById("sdr-nb-threshold-control
 var sdrNbThresholdEl = document.getElementById("sdr-nb-threshold");
 var sdrNbThresholdSetBtn = document.getElementById("sdr-nb-threshold-set");
 var sdrNbSupported = false;
+var sdrDigSidebandWrapEl = document.getElementById("sdr-dig-sideband-wrap");
+var sdrDigSidebandEl = document.getElementById("sdr-dig-sideband");
+var sdrDigSidebandSupported = false;
 fetch("/audio", { method: "GET" }).then((r) => {
   if (r.status === 404) audioRow.style.display = "none";
 }).catch(() => {
@@ -7019,11 +7029,26 @@ if (sdrNbThresholdEl) {
     }
   });
 }
+function submitSdrDigSideband() {
+  if (!sdrDigSidebandSupported || !sdrDigSidebandEl) return;
+  const policy = sdrDigSidebandEl.value || "auto";
+  if (policy !== "auto" && policy !== "usb" && policy !== "lsb") return;
+  postPath(`/set_sdr_dig_sideband?policy=${encodeURIComponent(policy)}`).catch(() => {
+  });
+}
+if (sdrDigSidebandEl) {
+  sdrDigSidebandEl.addEventListener("change", () => {
+    submitSdrDigSideband();
+  });
+}
 function updateWfmControls() {
   const mode = (modeEl && modeEl.value ? modeEl.value : "").toUpperCase();
   if (wfmControlsCol) wfmControlsCol.style.display = mode === "WFM" ? "" : "none";
   if (samControlsCol) samControlsCol.style.display = mode === "SAM" ? "" : "none";
   if (modeControlsRow) modeControlsRow.style.display = mode === "WFM" || mode === "SAM" ? "" : "none";
+  if (sdrDigSidebandWrapEl) {
+    sdrDigSidebandWrapEl.style.display = sdrDigSidebandSupported && mode === "DIG" ? "" : "none";
+  }
 }
 if (!hasWebCodecs) {
   rxAudioBtn.disabled = true;

src/trx-client/trx-frontend/trx-frontend-http/assets/web/generated/bookmarks.js

@@ -214,6 +214,12 @@ function bmBuildDecoderCheckboxes() {
     container.appendChild(label);
   });
 }
+function bmSyncDigSidebandVisibility() {
+  const label = bmOptionalEl("bm-dig-sideband-label");
+  if (!label) return;
+  const mode = (bmEl("bm-mode").value || "").trim().toUpperCase();
+  label.style.display = mode === "DIG" ? "" : "none";
+}
 function bmOpenForm(bm) {
   const wrap = bmEl("bm-form-wrap");
   if (!wrap) return;
@@ -227,7 +233,9 @@ function bmOpenForm(bm) {
   bmEl("bm-locator").value = bm ? bm.locator || "" : "";
   bmEl("bm-category-input").value = bm ? bm.category || "" : "";
   bmEl("bm-comment").value = bm ? bm.comment || "" : "";
+  bmEl("bm-dig-sideband").value = bm ? bm.dig_sideband || "" : "";
   bmWriteDecoders(bm?.decoders ?? []);
+  bmSyncDigSidebandVisibility();
   bmEl("bm-form-title").textContent = bm ? "Edit Bookmark" : "Add Bookmark";
   wrap.style.display = "flex";
   bmEl("bm-name").focus();
@@ -263,6 +271,7 @@ async function bmSave(e) {
   const category = bmEl("bm-category-input").value.trim();
   const comment = bmEl("bm-comment").value.trim();
   const decoders = bmReadDecoders();
+  const dig_sideband = mode.toUpperCase() === "DIG" ? bmEl("bm-dig-sideband").value || null : null;
   const formError = bmEl("bm-form-error");
   if (formError) formError.textContent = "";
   if (!name || !Number.isFinite(freq_hz) || !mode) {
@@ -279,7 +288,8 @@ async function bmSave(e) {
     locator: locator || null,
     category,
     comment,
-    decoders
+    decoders,
+    dig_sideband
   };
   try {
     let resp;
@@ -344,6 +354,12 @@ function bmApply(bm) {
     }
     const tunePromise = (async () => {
       await bridge.trx.modules.vchan?.takeSchedulerControl();
+      if ((bm.mode || "").toUpperCase() === "DIG" && bm.dig_sideband) {
+        const p = bm.dig_sideband.toLowerCase();
+        if (p === "auto" || p === "usb" || p === "lsb") {
+          await hostCore.postPath("/set_sdr_dig_sideband?policy=" + encodeURIComponent(p));
+        }
+      }
       const onVirtual = await bridge.trx.modules.vchan?.interceptMode(bm.mode) ?? false;
       if (!onVirtual) {
         await hostCore.postPath("/set_mode?mode=" + encodeURIComponent(bm.mode));
@@ -596,6 +612,7 @@ function bmPopulateScopePicker() {
   bmEl("bm-form").addEventListener("submit", (event) => {
     void bmSave(event);
   });
+  bmEl("bm-mode").addEventListener("input", bmSyncDigSidebandVisibility);
   bmEl("bm-form-cancel").addEventListener("click", bmCloseForm);
   const formWrap = bmEl("bm-form-wrap");
   if (formWrap) {

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

@@ -385,6 +385,14 @@ SPDX-License-Identifier: GPL-2.0-or-later
                   </label>
                   <button id="sdr-nb-threshold-set" type="button" class="wfm-inline-btn">Set</button>
                 </div>
+                <label class="wfm-control" id="sdr-dig-sideband-wrap" style="display:none;">
+                  <span class="wfm-control-label" title="Sideband used to demodulate DIG. Auto = USB &ge; 10 MHz, LSB below.">DIG sideband</span>
+                  <select id="sdr-dig-sideband" class="status-input">
+                    <option value="auto">Auto (by band)</option>
+                    <option value="usb">USB</option>
+                    <option value="lsb">LSB</option>
+                  </select>
+                </label>
               </div>
             </div>
             <div class="full-row label-below-row" id="vchan-row">
@@ -721,6 +729,14 @@ SPDX-License-Identifier: GPL-2.0-or-later
             <label class="bm-label">Bandwidth (Hz)
               <input type="number" id="bm-bw" class="status-input" min="0" placeholder="optional" />
             </label>
+            <label class="bm-label" id="bm-dig-sideband-label" style="display:none;">DIG sideband
+              <select id="bm-dig-sideband" class="status-input">
+                <option value="">Global setting</option>
+                <option value="auto">Auto (by band)</option>
+                <option value="usb">USB</option>
+                <option value="lsb">LSB</option>
+              </select>
+            </label>
             <label class="bm-label">Locator
               <input type="text" id="bm-locator" class="status-input" maxlength="6" placeholder="e.g. JO93" />
             </label>

src/trx-client/trx-frontend/trx-frontend-http/examples/generate_typescript.rs

@@ -12,7 +12,9 @@ use trx_core::rig::{
     RigAccessMethod, RigCapabilities, RigInfo, RigRxStatus, RigStatus, RigTxStatus, RigVfo,
     RigVfoEntry,
 };
-use trx_core::{DecoderConfig, RdsData, RigFilterState, RigMode, RigSnapshot, WfmDenoiseLevel};
+use trx_core::{
+    DecoderConfig, DigSidebandPolicy, RdsData, RigFilterState, RigMode, RigSnapshot, WfmDenoiseLevel,
+};
 use trx_frontend_http::server::api::rig::{RigListItem, RigListResponse};
 use trx_frontend_http::server::api::FrontendMeta;
 use trx_frontend_http::server::auth::AuthRole;
@@ -49,6 +51,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     export!(RigStatus);
     export!(DecoderConfig);
     export!(WfmDenoiseLevel);
+    export!(DigSidebandPolicy);
     export!(RigFilterState);
     export!(RdsData);
     export!(SpectrumData);

src/trx-client/trx-frontend/trx-frontend-http/frontend/src/api/generated.ts

@@ -55,7 +55,14 @@ export type DecoderConfig = { aprs_decode_enabled: boolean, hf_aprs_decode_enabl
 
 export type WfmDenoiseLevel = "off" | "auto" | "low" | "medium" | "high";
 
-export type RigFilterState = { bandwidth_hz: number, cw_center_hz: number, sdr_gain_db?: number | null, sdr_lna_gain_db?: number | null, sdr_agc_enabled?: boolean | null, sdr_squelch_enabled?: boolean | null, sdr_squelch_threshold_db?: number | null, sdr_nb_enabled?: boolean | null, sdr_nb_threshold?: number | null, wfm_deemphasis_us: number, wfm_stereo: boolean, wfm_stereo_detected: boolean, wfm_denoise: WfmDenoiseLevel, 
+export type DigSidebandPolicy = "auto" | "usb" | "lsb";
+
+export type RigFilterState = { bandwidth_hz: number, cw_center_hz: number, sdr_gain_db?: number | null, sdr_lna_gain_db?: number | null, sdr_agc_enabled?: boolean | null, sdr_squelch_enabled?: boolean | null, sdr_squelch_threshold_db?: number | null, sdr_nb_enabled?: boolean | null, sdr_nb_threshold?: number | null, 
+/**
+ * Current DIG sideband policy (SDR backends only). Surfaces in the UI as
+ * the advanced-controls "DIG sideband" selector.
+ */
+sdr_dig_sideband?: DigSidebandPolicy | null, wfm_deemphasis_us: number, wfm_stereo: boolean, wfm_stereo_detected: boolean, wfm_denoise: WfmDenoiseLevel, 
 /**
  * Co-Channel Interference level (0–100 scale).
  */

src/trx-client/trx-frontend/trx-frontend-http/frontend/src/app.ts

@@ -3681,6 +3681,13 @@ function render(update: AppUpdate) {
         }
       }
     }
+    if (typeof update.filter.sdr_dig_sideband === "string") {
+      sdrDigSidebandSupported = true;
+      if (sdrDigSidebandEl && document.activeElement !== sdrDigSidebandEl) {
+        sdrDigSidebandEl.value = update.filter.sdr_dig_sideband;
+      }
+      updateWfmControls();
+    }
   }
   if (typeof update.show_sdr_gain_control === "boolean") {
     if (sdrSettingsRowEl) sdrSettingsRowEl.style.display = update.show_sdr_gain_control ? "" : "none";
@@ -5611,6 +5618,9 @@ const sdrNbThresholdControlsEl = document.getElementById("sdr-nb-threshold-contr
 const sdrNbThresholdEl = document.getElementById("sdr-nb-threshold") as HTMLInputElement | null;
 const sdrNbThresholdSetBtn = document.getElementById("sdr-nb-threshold-set") as HTMLButtonElement | null;
 let sdrNbSupported = false;
+const sdrDigSidebandWrapEl = document.getElementById("sdr-dig-sideband-wrap");
+const sdrDigSidebandEl = document.getElementById("sdr-dig-sideband") as HTMLSelectElement | null;
+let sdrDigSidebandSupported = false;
 
 // Hide audio row if audio is not configured on the server
 fetch("/audio", { method: "GET" }).then((r) => {
@@ -6062,6 +6072,17 @@ if (sdrNbThresholdEl) {
     }
   });
 }
+function submitSdrDigSideband() {
+  if (!sdrDigSidebandSupported || !sdrDigSidebandEl) return;
+  const policy = sdrDigSidebandEl.value || "auto";
+  if (policy !== "auto" && policy !== "usb" && policy !== "lsb") return;
+  postPath(`/set_sdr_dig_sideband?policy=${encodeURIComponent(policy)}`).catch(() => {});
+}
+if (sdrDigSidebandEl) {
+  sdrDigSidebandEl.addEventListener("change", () => {
+    submitSdrDigSideband();
+  });
+}
 function updateWfmControls() {
   const mode = (modeEl && modeEl.value ? modeEl.value : "").toUpperCase();
   if (wfmControlsCol) wfmControlsCol.style.display = mode === "WFM" ? "" : "none";
@@ -6069,6 +6090,11 @@ function updateWfmControls() {
   // The row holds only these two, so it goes with them — an empty one would
   // still take a track and a gap in the tray, and draw its divider.
   if (modeControlsRow) modeControlsRow.style.display = (mode === "WFM" || mode === "SAM") ? "" : "none";
+  // DIG sideband selector is only meaningful in DIG mode on an SDR backend.
+  if (sdrDigSidebandWrapEl) {
+    sdrDigSidebandWrapEl.style.display =
+      sdrDigSidebandSupported && mode === "DIG" ? "" : "none";
+  }
 }
 
 // Show compatibility warning for non-Chromium browsers

src/trx-client/trx-frontend/trx-frontend-http/frontend/src/plugins/bookmarks.ts

@@ -19,6 +19,8 @@ interface Bookmark {
   category?: string | null;
   comment?: string | null;
   decoders?: string[];
+  /** DIG sideband override: "auto" | "usb" | "lsb". Empty/absent = global. */
+  dig_sideband?: string | null;
   scope?: string;
 }
 
@@ -321,6 +323,14 @@ function bmBuildDecoderCheckboxes() {
     });
 }
 
+/** Show the DIG-sideband override selector only when the mode field is DIG. */
+function bmSyncDigSidebandVisibility(): void {
+  const label = bmOptionalEl("bm-dig-sideband-label");
+  if (!label) return;
+  const mode = (bmEl("bm-mode").value || "").trim().toUpperCase();
+  label.style.display = mode === "DIG" ? "" : "none";
+}
+
 function bmOpenForm(bm: Bookmark | null): void {
   const wrap = bmEl("bm-form-wrap");
   if (!wrap) return;
@@ -338,7 +348,9 @@ function bmOpenForm(bm: Bookmark | null): void {
   bmEl("bm-locator").value = bm ? (bm.locator || "") : "";
   bmEl("bm-category-input").value = bm ? (bm.category || "") : "";
   bmEl("bm-comment").value = bm ? (bm.comment || "") : "";
+  bmEl("bm-dig-sideband").value = bm ? (bm.dig_sideband || "") : "";
   bmWriteDecoders(bm?.decoders ?? []);
+  bmSyncDigSidebandVisibility();
   bmEl("bm-form-title").textContent = bm ? "Edit Bookmark" : "Add Bookmark";
 
   wrap.style.display = "flex";
@@ -383,6 +395,9 @@ async function bmSave(e: Event): Promise<void> {
   const category = bmEl("bm-category-input").value.trim();
   const comment = bmEl("bm-comment").value.trim();
   const decoders = bmReadDecoders();
+  // Only meaningful for DIG; stored empty otherwise so it never overrides.
+  const dig_sideband =
+    mode.toUpperCase() === "DIG" ? (bmEl("bm-dig-sideband").value || null) : null;
 
   const formError = bmEl("bm-form-error");
   if (formError) formError.textContent = "";
@@ -403,6 +418,7 @@ async function bmSave(e: Event): Promise<void> {
     category,
     comment,
     decoders,
+    dig_sideband,
   };
 
   try {
@@ -477,6 +493,16 @@ function bmApply(bm: Bookmark): void {
     const tunePromise = (async () => {
       await bridge.trx.modules.vchan?.takeSchedulerControl();
 
+      // For a DIG bookmark carrying a sideband override, set the global DIG
+      // policy first so the backend resolves the intended sideband when DIG is
+      // applied. "auto" is honoured explicitly; an empty override is left alone.
+      if ((bm.mode || "").toUpperCase() === "DIG" && bm.dig_sideband) {
+        const p = bm.dig_sideband.toLowerCase();
+        if (p === "auto" || p === "usb" || p === "lsb") {
+          await hostCore.postPath("/set_sdr_dig_sideband?policy=" + encodeURIComponent(p));
+        }
+      }
+
       const onVirtual = await bridge.trx.modules.vchan?.interceptMode(bm.mode) ?? false;
       if (!onVirtual) {
         await hostCore.postPath("/set_mode?mode=" + encodeURIComponent(bm.mode));
@@ -770,6 +796,9 @@ function bmPopulateScopePicker() {
   // Form submit
   bmEl("bm-form").addEventListener("submit", (event) => { void bmSave(event); });
 
+  // Reveal the DIG-sideband override only while the mode field reads DIG.
+  bmEl("bm-mode").addEventListener("input", bmSyncDigSidebandVisibility);
+
   // Form cancel
   bmEl("bm-form-cancel").addEventListener("click", bmCloseForm);
 

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

@@ -37,6 +37,7 @@ pub struct BookmarkInput {
     pub comment: Option<String>,
     pub category: Option<String>,
     pub decoders: Option<Vec<String>>,
+    pub dig_sideband: Option<String>,
 }
 
 /// A bookmark with its owning scope tag for the list response.
@@ -88,6 +89,17 @@ fn normalize_bookmark_locator(locator: Option<String>) -> Option<String> {
     })
 }
 
+/// Normalize a DIG sideband override to `auto`/`usb`/`lsb`, or `None` when
+/// absent or unrecognized (leaves the current policy untouched on apply).
+fn normalize_dig_sideband(value: Option<String>) -> Option<String> {
+    value.and_then(|v| match v.trim().to_lowercase().as_str() {
+        "auto" => Some("auto".to_string()),
+        "usb" => Some("usb".to_string()),
+        "lsb" => Some("lsb".to_string()),
+        _ => None,
+    })
+}
+
 // ============================================================================
 // Endpoints
 // ============================================================================
@@ -182,6 +194,7 @@ pub async fn create_bookmark(
         comment: body.comment.clone().unwrap_or_default(),
         category: body.category.clone().unwrap_or_default(),
         decoders: body.decoders.clone().unwrap_or_default(),
+        dig_sideband: normalize_dig_sideband(body.dig_sideband.clone()),
     };
     if store.insert(&bm) {
         Ok(HttpResponse::Created().json(bm))
@@ -219,6 +232,7 @@ pub async fn update_bookmark(
         comment: body.comment.clone().unwrap_or_default(),
         category: body.category.clone().unwrap_or_default(),
         decoders: body.decoders.clone().unwrap_or_default(),
+        dig_sideband: normalize_dig_sideband(body.dig_sideband.clone()),
     };
     if store.upsert(&id, &bm) {
         Ok(HttpResponse::Ok().json(bm))

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

@@ -595,6 +595,7 @@ pub fn configure(cfg: &mut web::ServiceConfig) {
         .service(rig::set_sdr_agc)
         .service(rig::set_sdr_squelch)
         .service(rig::set_sdr_noise_blanker)
+        .service(rig::set_sdr_dig_sideband)
         .service(rig::set_wfm_deemphasis)
         .service(rig::set_wfm_stereo)
         .service(rig::set_wfm_denoise)

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

@@ -14,7 +14,7 @@ use uuid::Uuid;
 
 use trx_core::radio::freq::Freq;
 use trx_core::rig::state::WfmDenoiseLevel;
-use trx_core::{RigCommand, RigRequest, RigState};
+use trx_core::{DigSidebandPolicy, RigCommand, RigRequest, RigState};
 use trx_frontend::{FrontendRuntimeContext, RemoteRigEntry};
 use trx_protocol::parse_mode;
 
@@ -299,6 +299,23 @@ pub async fn set_sdr_noise_blanker(
     .await
 }
 
+#[derive(serde::Deserialize)]
+pub struct SdrDigSidebandQuery {
+    /// `auto`, `usb`, or `lsb`.
+    pub policy: DigSidebandPolicy,
+    pub remote: Option<String>,
+}
+
+/// Set how the SDR backend resolves DIG mode to a sideband.
+#[post("/set_sdr_dig_sideband")]
+pub async fn set_sdr_dig_sideband(
+    query: web::Query<SdrDigSidebandQuery>,
+    rig_tx: web::Data<mpsc::Sender<RigRequest>>,
+) -> Result<HttpResponse, Error> {
+    let q = query.into_inner();
+    send_command(&rig_tx, RigCommand::SetSdrDigSideband(q.policy), q.remote).await
+}
+
 // ============================================================================
 // WFM / SAM settings
 // ============================================================================

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

@@ -21,6 +21,10 @@ pub struct Bookmark {
     pub comment: String,
     pub category: String,
     pub decoders: Vec<String>,
+    /// For `DIG` bookmarks, the sideband policy to apply on tune: `auto`,
+    /// `usb`, or `lsb`. `None` (or non-DIG) leaves the current policy alone.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub dig_sideband: Option<String>,
 }
 
 pub struct BookmarkStore {

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

@@ -592,6 +592,21 @@ async fn apply_scheduler_target(
     )
     .await?;
 
+    // Apply any DIG sideband override before switching to DIG so the SDR
+    // backend resolves the intended sideband for this bookmark.
+    if let Some(policy) = bookmark
+        .dig_sideband
+        .as_deref()
+        .and_then(trx_core::DigSidebandPolicy::parse)
+    {
+        scheduler_send(
+            rig_tx,
+            RigCommand::SetSdrDigSideband(policy),
+            remote.to_string(),
+        )
+        .await?;
+    }
+
     scheduler_send(
         rig_tx,
         RigCommand::SetMode(trx_protocol::parse_mode(&bookmark.mode)),