[feat](trx-rs): redesign SDR noise blanker with tuning profiles

The old IQ noise blanker tracked a fast running RMS and, on a
threshold crossing, replaced the sample with the last clean one. That
hard sample-and-hold is a step discontinuity: it splatters energy back
across the wideband passband, so after the narrow channel filter it
often sounded worse than the noise it removed — especially on SSB, CW
and digital. It also had no look-ahead (the impulse leading edge leaked
through before the fast RMS reacted), blanked only single samples, and
used a fixed 1/128 time constant that did not scale with capture rate.

Redesign the blanker around accepted wideband-NB practice and add
profiles matched to the interference source:

- Noise-floor tracker updated only from clean samples and frozen while
  blanking, so a burst cannot desensitise detection.
- Detection on instantaneous power vs threshold² × noise floor.
- Look-ahead delay line so the gate closes *before* the impulse reaches
  the output, removing the leading edge.
- Raised-cosine tapered gate (ramp 1→0→1) instead of a hard hold, which
  minimises blanker splatter.
- Windowed blanking that re-arms on every detected sample to cover the
  full width of a burst.
- All timings expressed in real time and converted to samples at the
  capture rate, so behaviour is consistent across SDR sample rates.

Profiles (`NoiseBlankerProfile`, default `spike`): spike, ignition,
powerline, broadband — each selects the blank window, look-ahead, taper
and floor time constant. `threshold` stays orthogonal as the
sensitivity knob.

Core/protocol:
- New `NoiseBlankerProfile` in trx-core (serde/parse/u8/TS), re-exported
  at the crate root; `RigFilterState.sdr_nb_profile` for state sync.
- `profile` added to `RigCommand`/`ClientCommand::SetSdrNoiseBlanker`,
  the trait method, and the command mapping.

Config: `[rig.sdr.noise_blanker] profile = "spike"` (regenerated
trx-rs.toml.example).

SDR backend: `NoiseBlanker` rewritten in the channel DSP; profile wired
through `SoapySdrConfig`, the runtime setter, and `filter_state()`.

Frontend: an "NB profile" selector in the SDR advanced controls
(POST /set_sdr_noise_blanker&profile=…), reflecting server state; the
profile rides along with the enable/threshold quick toggle so it is
preserved. Regenerated generated.ts and app.js.

Tests: profile u8/parse round-trips (trx-core); DSP tests for impulse
suppression with no leading-edge leak, strong-steady-signal
pass-through, and wider-profile-blanks-longer.

Docs: User-Manual NB section rewritten for the new algorithm and
profiles.

Signed-off-by: Stan Grams <sjg@haxx.space>

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

@@ -4766,6 +4766,13 @@ function render(update) {
           sdrNbThresholdEl.value = String(Math.round(update.filter.sdr_nb_threshold));
         }
       }
+      if (typeof update.filter.sdr_nb_profile === "string") {
+        sdrNbProfile = update.filter.sdr_nb_profile;
+        if (sdrNbProfileWrapEl) sdrNbProfileWrapEl.style.display = "";
+        if (sdrNbProfileEl && document.activeElement !== sdrNbProfileEl) {
+          sdrNbProfileEl.value = update.filter.sdr_nb_profile;
+        }
+      }
     }
     if (typeof update.filter.sdr_dig_sideband === "string") {
       sdrDigSidebandSupported = true;
@@ -6644,7 +6651,10 @@ var sdrNbEnabledEl = document.getElementById("sdr-nb-enabled");
 var sdrNbThresholdControlsEl = document.getElementById("sdr-nb-threshold-controls");
 var sdrNbThresholdEl = document.getElementById("sdr-nb-threshold");
 var sdrNbThresholdSetBtn = document.getElementById("sdr-nb-threshold-set");
+var sdrNbProfileWrapEl = document.getElementById("sdr-nb-profile-wrap");
+var sdrNbProfileEl = document.getElementById("sdr-nb-profile");
 var sdrNbSupported = false;
+var sdrNbProfile = "spike";
 var sdrDigSidebandWrapEl = document.getElementById("sdr-dig-sideband-wrap");
 var sdrDigSidebandEl = document.getElementById("sdr-dig-sideband");
 var sdrDigSidebandSupported = false;
@@ -7019,7 +7029,7 @@ function submitSdrNbState() {
   const threshold = sdrNbThresholdEl ? Number.parseFloat(sdrNbThresholdEl.value) : 10;
   if (!isFiniteNumber(threshold) || threshold < 1 || threshold > 100) return;
   postPath(
-    `/set_sdr_noise_blanker?enabled=${enabled ? "true" : "false"}&threshold=${encodeURIComponent(threshold)}`
+    `/set_sdr_noise_blanker?enabled=${enabled ? "true" : "false"}&threshold=${encodeURIComponent(threshold)}&profile=${encodeURIComponent(sdrNbProfile)}`
   ).catch(() => {
   });
 }
@@ -7028,6 +7038,16 @@ if (sdrNbEnabledEl) {
     submitSdrNbState();
   });
 }
+if (sdrNbProfileEl) {
+  sdrNbProfileEl.addEventListener("change", () => {
+    const profile = sdrNbProfileEl.value || "spike";
+    if (profile !== "spike" && profile !== "ignition" && profile !== "powerline" && profile !== "broadband") {
+      return;
+    }
+    sdrNbProfile = profile;
+    submitSdrNbState();
+  });
+}
 function submitSdrNbThreshold() {
   if (!sdrNbThresholdEl) return;
   const parsed = Number.parseFloat(sdrNbThresholdEl.value);

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

@@ -385,6 +385,15 @@ 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-nb-profile-wrap" style="display:none;">
+                  <span class="wfm-control-label" title="Matches the blanker to the interference: Spike = sharp bursts, Ignition = engine/PWM, Powerline = mains buzz, Broadband = dense noise.">NB profile</span>
+                  <select id="sdr-nb-profile" class="status-input">
+                    <option value="spike">Spike</option>
+                    <option value="ignition">Ignition</option>
+                    <option value="powerline">Powerline</option>
+                    <option value="broadband">Broadband</option>
+                  </select>
+                </label>
                 <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">

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

@@ -13,8 +13,8 @@ use trx_core::rig::{
     RigVfoEntry,
 };
 use trx_core::{
-    DecoderConfig, DigSidebandPolicy, RdsData, RigFilterState, RigMode, RigSnapshot,
-    WfmDenoiseLevel,
+    DecoderConfig, DigSidebandPolicy, NoiseBlankerProfile, RdsData, RigFilterState, RigMode,
+    RigSnapshot, WfmDenoiseLevel,
 };
 use trx_frontend_http::server::api::rig::{RigListItem, RigListResponse};
 use trx_frontend_http::server::api::FrontendMeta;
@@ -53,6 +53,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     export!(DecoderConfig);
     export!(WfmDenoiseLevel);
     export!(DigSidebandPolicy);
+    export!(NoiseBlankerProfile);
     export!(RigFilterState);
     export!(RdsData);
     export!(SpectrumData);

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

@@ -57,7 +57,14 @@ export type WfmDenoiseLevel = "off" | "auto" | "low" | "medium" | "high";
 
 export type DigSidebandPolicy = "auto" | "usb" | "lsb";
 
+export type NoiseBlankerProfile = "spike" | "ignition" | "powerline" | "broadband";
+
 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 noise-blanker tuning profile (SDR backends only). Surfaces in the
+ * UI as the advanced-controls "NB profile" selector.
+ */
+sdr_nb_profile?: NoiseBlankerProfile | null, 
 /**
  * Current DIG sideband policy (SDR backends only). Surfaces in the UI as
  * the advanced-controls "DIG sideband" selector.

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

@@ -3696,6 +3696,13 @@ function render(update: AppUpdate) {
           sdrNbThresholdEl.value = String(Math.round(update.filter.sdr_nb_threshold));
         }
       }
+      if (typeof update.filter.sdr_nb_profile === "string") {
+        sdrNbProfile = update.filter.sdr_nb_profile;
+        if (sdrNbProfileWrapEl) sdrNbProfileWrapEl.style.display = "";
+        if (sdrNbProfileEl && document.activeElement !== sdrNbProfileEl) {
+          sdrNbProfileEl.value = update.filter.sdr_nb_profile;
+        }
+      }
     }
     if (typeof update.filter.sdr_dig_sideband === "string") {
       sdrDigSidebandSupported = true;
@@ -5639,7 +5646,12 @@ const sdrNbEnabledEl = document.getElementById("sdr-nb-enabled") as HTMLInputEle
 const sdrNbThresholdControlsEl = document.getElementById("sdr-nb-threshold-controls");
 const sdrNbThresholdEl = document.getElementById("sdr-nb-threshold") as HTMLInputElement | null;
 const sdrNbThresholdSetBtn = document.getElementById("sdr-nb-threshold-set") as HTMLButtonElement | null;
+const sdrNbProfileWrapEl = document.getElementById("sdr-nb-profile-wrap");
+const sdrNbProfileEl = document.getElementById("sdr-nb-profile") as HTMLSelectElement | null;
 let sdrNbSupported = false;
+// Current NB profile, mirrored from server filter state; sent alongside every
+// enable/threshold change (including the quick toggle) so it is preserved.
+let sdrNbProfile = "spike";
 const sdrDigSidebandWrapEl = document.getElementById("sdr-dig-sideband-wrap");
 const sdrDigSidebandEl = document.getElementById("sdr-dig-sideband") as HTMLSelectElement | null;
 let sdrDigSidebandSupported = false;
@@ -6074,7 +6086,7 @@ function submitSdrNbState() {
   const threshold = sdrNbThresholdEl ? Number.parseFloat(sdrNbThresholdEl.value) : 10;
   if (!isFiniteNumber(threshold) || threshold < 1 || threshold > 100) return;
   postPath(
-    `/set_sdr_noise_blanker?enabled=${enabled ? "true" : "false"}&threshold=${encodeURIComponent(threshold)}`,
+    `/set_sdr_noise_blanker?enabled=${enabled ? "true" : "false"}&threshold=${encodeURIComponent(threshold)}&profile=${encodeURIComponent(sdrNbProfile)}`,
   ).catch(() => {});
 }
 if (sdrNbEnabledEl) {
@@ -6082,6 +6094,21 @@ if (sdrNbEnabledEl) {
     submitSdrNbState();
   });
 }
+if (sdrNbProfileEl) {
+  sdrNbProfileEl.addEventListener("change", () => {
+    const profile = sdrNbProfileEl.value || "spike";
+    if (
+      profile !== "spike" &&
+      profile !== "ignition" &&
+      profile !== "powerline" &&
+      profile !== "broadband"
+    ) {
+      return;
+    }
+    sdrNbProfile = profile;
+    submitSdrNbState();
+  });
+}
 function submitSdrNbThreshold() {
   if (!sdrNbThresholdEl) return;
   const parsed = Number.parseFloat(sdrNbThresholdEl.value);

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::{DigSidebandPolicy, RigCommand, RigRequest, RigState};
+use trx_core::{DigSidebandPolicy, NoiseBlankerProfile, RigCommand, RigRequest, RigState};
 use trx_frontend::{FrontendRuntimeContext, RemoteRigEntry};
 use trx_protocol::parse_mode;
 
@@ -279,6 +279,10 @@ pub async fn set_sdr_squelch(
 pub struct SdrNoiseBlankerQuery {
     pub enabled: bool,
     pub threshold: f64,
+    /// `spike` (default), `ignition`, `powerline`, or `broadband`. Optional so
+    /// the quick toggle (which only carries enable/threshold) keeps working.
+    #[serde(default)]
+    pub profile: NoiseBlankerProfile,
     pub remote: Option<String>,
 }
 
@@ -293,6 +297,7 @@ pub async fn set_sdr_noise_blanker(
         RigCommand::SetSdrNoiseBlanker {
             enabled: q.enabled,
             threshold: q.threshold,
+            profile: q.profile,
         },
         q.remote,
     )

src/trx-config/src/server.rs

@@ -19,7 +19,7 @@ use crate::shared::{check_socket_conflicts, validate_log_level, validate_tokens,
 use serde::{Deserialize, Serialize};
 pub use trx_decode_log::DecodeLogsConfig;
 
-use trx_core::rig::state::{DigSidebandPolicy, RigMode};
+use trx_core::rig::state::{DigSidebandPolicy, NoiseBlankerProfile, RigMode};
 
 /// Every decoder the server knows how to run, by config name.
 ///
@@ -478,8 +478,14 @@ pub struct SdrNoiseBlankerConfig {
     /// Enables the noise blanker.
     pub enabled: bool,
     /// Threshold multiplier for impulse detection (typical range: 1..100).
-    /// A sample whose magnitude exceeds threshold × running RMS is blanked.
+    /// A sample whose magnitude exceeds threshold × the tracked noise floor is
+    /// blanked. Lower values blank more aggressively.
     pub threshold: f64,
+    /// Tuning profile matched to the interference source: `spike` (default),
+    /// `ignition`, `powerline`, or `broadband`. Selects the blank window width,
+    /// look-ahead, gate taper, and noise-floor time constant.
+    #[serde(default)]
+    pub profile: NoiseBlankerProfile,
 }
 
 impl Default for SdrNoiseBlankerConfig {
@@ -487,6 +493,7 @@ impl Default for SdrNoiseBlankerConfig {
         Self {
             enabled: false,
             threshold: 10.0,
+            profile: NoiseBlankerProfile::Spike,
         }
     }
 }

src/trx-core/src/lib.rs

@@ -16,7 +16,7 @@ pub use rig::command::RigCommand;
 pub use rig::request::RigRequest;
 pub use rig::response::{RigError, RigResult};
 pub use rig::state::{
-    DecoderConfig, DecoderResetSeqs, DigSidebandPolicy, RdsData, RigFilterState, RigMode,
-    RigSnapshot, RigState, WfmDenoiseLevel,
+    DecoderConfig, DecoderResetSeqs, DigSidebandPolicy, NoiseBlankerProfile, RdsData,
+    RigFilterState, RigMode, RigSnapshot, RigState, WfmDenoiseLevel,
 };
 pub use rig::AudioSource;

src/trx-core/src/rig/command.rs

@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 use crate::radio::freq::Freq;
-use crate::rig::state::{DigSidebandPolicy, WfmDenoiseLevel};
+use crate::rig::state::{DigSidebandPolicy, NoiseBlankerProfile, WfmDenoiseLevel};
 use crate::RigMode;
 
 /// Internal command handled by the rig task.
@@ -55,6 +55,7 @@ pub enum RigCommand {
     SetSdrNoiseBlanker {
         enabled: bool,
         threshold: f64,
+        profile: NoiseBlankerProfile,
     },
     /// Set how the SDR backend resolves DIG mode to a sideband (SDR only).
     SetSdrDigSideband(DigSidebandPolicy),

src/trx-core/src/rig/mod.rs

@@ -253,6 +253,7 @@ pub trait RigSdr: Send {
         &'a mut self,
         _enabled: bool,
         _threshold: f64,
+        _profile: crate::rig::state::NoiseBlankerProfile,
     ) -> Pin<Box<dyn Future<Output = DynResult<()>> + Send + 'a>> {
         Box::pin(std::future::ready(Err(
             Box::new(response::RigError::not_supported("set_sdr_noise_blanker"))

src/trx-core/src/rig/state.rs

@@ -338,6 +338,10 @@ pub struct RigFilterState {
     pub sdr_nb_enabled: Option<bool>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub sdr_nb_threshold: Option<f64>,
+    /// Current noise-blanker tuning profile (SDR backends only). Surfaces in the
+    /// UI as the advanced-controls "NB profile" selector.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub sdr_nb_profile: Option<NoiseBlankerProfile>,
     /// Current DIG sideband policy (SDR backends only). Surfaces in the UI as
     /// the advanced-controls "DIG sideband" selector.
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -457,6 +461,72 @@ pub fn effective_demod_mode(logical: &RigMode, policy: DigSidebandPolicy, freq_h
     }
 }
 
+/// Tuning profile for the SDR impulse noise blanker.
+///
+/// The blanker removes short, wideband impulse noise from the IQ stream before
+/// down-conversion. Different interference sources have different pulse widths
+/// and repetition rates, so a single blank window cannot serve all of them: too
+/// narrow and it clips only the tip of a wide power-line burst, too wide and it
+/// punches audible holes in the wanted signal on sparse ignition spikes. Each
+/// profile selects a matched blank window, look-ahead, gate taper, and
+/// noise-floor time constant (the concrete values live in the SDR DSP, since
+/// they are converted to samples at the capture rate). The user-facing
+/// `threshold` control is orthogonal — it sets detection sensitivity within the
+/// chosen profile.
+#[derive(Debug, Clone, Copy, Default, Serialize, Deserialize, PartialEq, Eq, TS)]
+#[serde(rename_all = "lowercase")]
+pub enum NoiseBlankerProfile {
+    /// Short, sharp, sparse impulses — ignition sparks, static crashes, keyed
+    /// relays. Narrow blank window and fast recovery for minimal impact on the
+    /// wanted signal; the safe default for SSB/CW/digital.
+    #[default]
+    Spike,
+    /// Automotive ignition, electric fences, PWM/LED drivers — clusters of
+    /// medium-width pulses at a high repetition rate. Wider window than `Spike`.
+    Ignition,
+    /// Power-line and arcing noise — buzzy bursts locked to the 100/120 Hz mains
+    /// cycle. Wide blank window with a longer, slower noise-floor tracker.
+    Powerline,
+    /// Dense, continuous impulse noise where suppression matters more than
+    /// fidelity. Widest window and most aggressive gating; expect some softening
+    /// of the wanted signal.
+    Broadband,
+}
+
+impl NoiseBlankerProfile {
+    /// Compact encoding for storage in an atomic or terse wire field.
+    pub fn to_u8(self) -> u8 {
+        match self {
+            NoiseBlankerProfile::Spike => 0,
+            NoiseBlankerProfile::Ignition => 1,
+            NoiseBlankerProfile::Powerline => 2,
+            NoiseBlankerProfile::Broadband => 3,
+        }
+    }
+
+    /// Inverse of [`NoiseBlankerProfile::to_u8`]; unknown values decode to the
+    /// default `Spike`.
+    pub fn from_u8(v: u8) -> Self {
+        match v {
+            1 => NoiseBlankerProfile::Ignition,
+            2 => NoiseBlankerProfile::Powerline,
+            3 => NoiseBlankerProfile::Broadband,
+            _ => NoiseBlankerProfile::Spike,
+        }
+    }
+
+    /// Parse a case-insensitive profile name; `None` if unknown.
+    pub fn parse(s: &str) -> Option<Self> {
+        match s.trim().to_ascii_lowercase().as_str() {
+            "spike" => Some(NoiseBlankerProfile::Spike),
+            "ignition" => Some(NoiseBlankerProfile::Ignition),
+            "powerline" => Some(NoiseBlankerProfile::Powerline),
+            "broadband" => Some(NoiseBlankerProfile::Broadband),
+            _ => None,
+        }
+    }
+}
+
 fn default_wfm_deemphasis_us() -> u32 {
     75
 }
@@ -657,3 +727,47 @@ mod dig_sideband_tests {
         assert_eq!(DigSidebandPolicy::parse("nonsense"), None);
     }
 }
+
+#[cfg(test)]
+mod noise_blanker_profile_tests {
+    use super::NoiseBlankerProfile;
+
+    #[test]
+    fn default_is_spike() {
+        assert_eq!(NoiseBlankerProfile::default(), NoiseBlankerProfile::Spike);
+    }
+
+    #[test]
+    fn u8_round_trips() {
+        for p in [
+            NoiseBlankerProfile::Spike,
+            NoiseBlankerProfile::Ignition,
+            NoiseBlankerProfile::Powerline,
+            NoiseBlankerProfile::Broadband,
+        ] {
+            assert_eq!(NoiseBlankerProfile::from_u8(p.to_u8()), p);
+        }
+        // Unknown encodings fall back to the default.
+        assert_eq!(
+            NoiseBlankerProfile::from_u8(200),
+            NoiseBlankerProfile::Spike
+        );
+    }
+
+    #[test]
+    fn parse_is_case_insensitive() {
+        assert_eq!(
+            NoiseBlankerProfile::parse("SPIKE"),
+            Some(NoiseBlankerProfile::Spike)
+        );
+        assert_eq!(
+            NoiseBlankerProfile::parse(" powerline "),
+            Some(NoiseBlankerProfile::Powerline)
+        );
+        assert_eq!(
+            NoiseBlankerProfile::parse("Broadband"),
+            Some(NoiseBlankerProfile::Broadband)
+        );
+        assert_eq!(NoiseBlankerProfile::parse("nonsense"), None);
+    }
+}

src/trx-protocol/src/codec.rs

@@ -343,6 +343,7 @@ mod tests {
                 sdr_squelch_threshold_db: None,
                 sdr_nb_enabled: None,
                 sdr_nb_threshold: None,
+                sdr_nb_profile: None,
                 sdr_dig_sideband: None,
                 wfm_deemphasis_us: 75,
                 wfm_stereo: true,
@@ -392,6 +393,7 @@ mod tests {
                 sdr_squelch_threshold_db: None,
                 sdr_nb_enabled: None,
                 sdr_nb_threshold: None,
+                sdr_nb_profile: None,
                 sdr_dig_sideband: None,
                 wfm_deemphasis_us: 50,
                 wfm_stereo: true,

src/trx-protocol/src/mapping.rs

@@ -157,7 +157,7 @@ define_command_mapping! {
     // ── Multi-field struct passthrough ───────────────────────────────
     multi:
         SetSdrSquelch      { enabled, threshold_db } <=> SetSdrSquelch,
-        SetSdrNoiseBlanker { enabled, threshold }    <=> SetSdrNoiseBlanker;
+        SetSdrNoiseBlanker { enabled, threshold, profile } <=> SetSdrNoiseBlanker;
 
     // ── Freq conversions (u64 <=> Freq) ──────────────────────────────
     freq:

src/trx-protocol/src/types.rs

@@ -7,7 +7,7 @@
 use serde::{Deserialize, Serialize};
 
 use trx_core::rig::state::RigSnapshot;
-use trx_core::{DigSidebandPolicy, WfmDenoiseLevel};
+use trx_core::{DigSidebandPolicy, NoiseBlankerProfile, WfmDenoiseLevel};
 
 /// Command received from network clients (JSON).
 #[derive(Debug, Serialize, Deserialize)]
@@ -105,6 +105,7 @@ pub enum ClientCommand {
     SetSdrNoiseBlanker {
         enabled: bool,
         threshold: f64,
+        profile: NoiseBlankerProfile,
     },
     SetSdrDigSideband {
         policy: DigSidebandPolicy,

src/trx-server/src/main.rs

@@ -360,6 +360,7 @@ fn build_sdr_rig_from_instance(rig_cfg: &RigInstanceConfig) -> SdrRigBuildResult
         max_virtual_channels: rig_cfg.sdr.max_virtual_channels,
         nb_enabled: rig_cfg.sdr.noise_blanker.enabled,
         nb_threshold: rig_cfg.sdr.noise_blanker.threshold,
+        nb_profile: rig_cfg.sdr.noise_blanker.profile,
         dig_sideband: rig_cfg.sdr.dig_sideband,
         spectrum_fft_size: rig_cfg.sdr.spectrum_fft_size,
     })?;

src/trx-server/src/rig_task.rs

@@ -760,9 +760,13 @@ async fn process_command(
             let _ = ctx.state_tx.send(ctx.state.clone());
             return snapshot_from(ctx.state);
         }
-        RigCommand::SetSdrNoiseBlanker { enabled, threshold } => {
+        RigCommand::SetSdrNoiseBlanker {
+            enabled,
+            threshold,
+            profile,
+        } => {
             if let Some(sdr) = ctx.rig.as_sdr() {
-                if let Err(e) = sdr.set_sdr_noise_blanker(enabled, threshold).await {
+                if let Err(e) = sdr.set_sdr_noise_blanker(enabled, threshold, profile).await {
                     return Err(RigError::communication(format!(
                         "set_sdr_noise_blanker: {e}"
                     )));

src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp/channel.rs

@@ -4,7 +4,7 @@
 
 use num_complex::Complex;
 use tokio::sync::broadcast;
-use trx_core::rig::state::{RdsData, RigMode, WfmDenoiseLevel};
+use trx_core::rig::state::{NoiseBlankerProfile, RdsData, RigMode, WfmDenoiseLevel};
 
 use crate::demod::{DcBlocker, Demodulator, SamDemod, SoftAgc, WfmStereoDecoder};
 
@@ -14,38 +14,174 @@ use super::{BlockFirFilterPair, IQ_BLOCK_SIZE};
 // Noise blanker
 // ---------------------------------------------------------------------------
 
-/// IQ-domain impulse noise blanker.
+/// Temporal shape of a [`NoiseBlankerProfile`], in real time so the numbers
+/// scale correctly across capture rates (they are converted to samples at
+/// runtime). See [`NoiseBlanker`] for how each field is used.
+struct NbShape {
+    /// Delay applied to the stream so the gate can begin closing *before* a
+    /// detected impulse reaches the output, catching its leading edge.
+    lookahead_us: f32,
+    /// Minimum time the gate is held fully closed after each detected sample.
+    blank_us: f32,
+    /// Raised-cosine gate ramp length (attack == release).
+    ramp_us: f32,
+    /// Time constant of the exponential noise-floor tracker.
+    ref_tc_ms: f32,
+}
+
+impl NbShape {
+    const fn for_profile(p: NoiseBlankerProfile) -> Self {
+        match p {
+            // Short, sparse spikes: tight window, quick recovery, fast floor.
+            NoiseBlankerProfile::Spike => NbShape {
+                lookahead_us: 8.0,
+                blank_us: 24.0,
+                ramp_us: 5.0,
+                ref_tc_ms: 4.0,
+            },
+            // Ignition/PWM bursts: medium window at a high repetition rate.
+            NoiseBlankerProfile::Ignition => NbShape {
+                lookahead_us: 12.0,
+                blank_us: 80.0,
+                ramp_us: 8.0,
+                ref_tc_ms: 4.0,
+            },
+            // Power-line buzz: wide window, slow floor to ride out the burst.
+            NoiseBlankerProfile::Powerline => NbShape {
+                lookahead_us: 20.0,
+                blank_us: 200.0,
+                ramp_us: 12.0,
+                ref_tc_ms: 15.0,
+            },
+            // Dense impulse noise: widest, most aggressive gating.
+            NoiseBlankerProfile::Broadband => NbShape {
+                lookahead_us: 24.0,
+                blank_us: 400.0,
+                ramp_us: 16.0,
+                ref_tc_ms: 8.0,
+            },
+        }
+    }
+}
+
+/// Floor for the tracked noise-floor estimate, guarding against a zero divisor
+/// and cold-start false triggers.
+const NB_MIN_REF: f32 = 1e-12;
+
+/// IQ-domain impulse noise blanker with look-ahead and a tapered gate.
 ///
-/// Maintains a running RMS estimate of the IQ magnitude.  When a sample's
-/// magnitude exceeds `threshold × rms`, it is replaced by linear interpolation
-/// between the last clean sample and the next clean sample (lookahead of 1).
+/// This runs on the wide, undecimated IQ stream — the only place an impulse is
+/// still short in time (narrow filtering downstream smears it into un-removable
+/// ringing). The algorithm has four parts:
 ///
-/// The RMS tracker uses exponential smoothing with a time constant of ~128
-/// samples at the IQ sample rate, fast enough to track band-noise changes
-/// but slow enough not to follow individual impulses.
+/// 1. **Noise-floor tracker** — an exponential mean-square estimate updated
+///    *only from clean samples* and frozen while blanking, so a burst cannot
+///    drag the reference up and desensitise detection. Its time constant comes
+///    from the profile.
+/// 2. **Detection** — a sample is an impulse when its instantaneous power
+///    exceeds `threshold² × noise_floor`. `threshold` is the user sensitivity
+///    knob and is orthogonal to the profile.
+/// 3. **Look-ahead** — the signal is delayed by `lookahead` samples so the gate
+///    can start closing before the impulse reaches the output, removing the
+///    leading edge instead of letting it leak through (the old blanker's main
+///    failure). Each detection holds the gate shut for a profile-sized window.
+/// 4. **Tapered gate** — instead of the old hard sample-and-hold (a step that
+///    splattered energy right back across the passband and made the blanker
+///    audibly worse on SSB/CW/data), the gain ramps smoothly 1→0→1 over
+///    `ramp` samples, so blanking costs only a short, quiet notch.
 #[derive(Debug, Clone)]
 pub struct NoiseBlanker {
     enabled: bool,
+    profile: NoiseBlankerProfile,
+    sample_rate: f32,
+    /// Detection sensitivity multiplier over the tracked noise floor (>= 1).
     threshold: f32,
-    /// Exponentially-smoothed mean-square estimate.
-    mean_sq: f32,
-    /// Last clean sample (used for interpolation fill).
-    last_clean: Complex<f32>,
+
+    // Derived from (profile, sample_rate); recomputed when either changes.
+    lookahead: usize,
+    blank_samples: usize,
+    /// Per-sample gate gain increment; `1.0 / ramp_len`.
+    ramp_step: f32,
+    /// Noise-floor EMA coefficient.
+    ref_alpha: f32,
+    /// Samples to seed the noise floor before detection is trusted.
+    warmup: u32,
+
+    // Streaming state.
+    /// Look-ahead ring buffer (length `lookahead`; empty when `lookahead == 0`).
+    delay: Vec<Complex<f32>>,
+    dpos: usize,
+    /// Tracked noise-floor mean-square.
+    ref_sq: f32,
+    /// Samples processed since (re)configuration, capped at `warmup`.
+    seen: u32,
+    /// Remaining forced-blank samples.
+    hold: usize,
+    /// Current gate gain in `0.0..=1.0`.
+    gain: f32,
 }
 
-const NB_ALPHA: f32 = 1.0 / 128.0;
-
 impl NoiseBlanker {
-    pub fn new(enabled: bool, threshold: f32) -> Self {
-        Self {
-            enabled,
-            threshold: threshold.max(1.0),
-            mean_sq: 1e-10,
-            last_clean: Complex::new(0.0, 0.0),
+    pub fn new(cfg: NoiseBlankerConfig, sample_rate: u32) -> Self {
+        let mut nb = Self {
+            enabled: cfg.enabled,
+            profile: cfg.profile,
+            sample_rate: sample_rate as f32,
+            threshold: cfg.threshold.max(1.0),
+            lookahead: 0,
+            blank_samples: 0,
+            ramp_step: 1.0,
+            ref_alpha: 0.0,
+            warmup: 0,
+            delay: Vec::new(),
+            dpos: 0,
+            ref_sq: NB_MIN_REF,
+            seen: 0,
+            hold: 0,
+            gain: 1.0,
+        };
+        nb.recompute();
+        nb
+    }
+
+    /// Recompute sample-domain parameters from the current profile and sample
+    /// rate, then clear streaming state so the new geometry starts clean.
+    fn recompute(&mut self) {
+        let sr = self.sample_rate.max(1.0);
+        let shape = NbShape::for_profile(self.profile);
+        let per_us = sr / 1_000_000.0;
+
+        self.lookahead = ((shape.lookahead_us * per_us).round() as usize).max(1);
+        self.blank_samples = ((shape.blank_us * per_us).round() as usize).max(1);
+        let ramp_len = (shape.ramp_us * per_us).round().max(1.0);
+        self.ramp_step = 1.0 / ramp_len;
+        let ref_tc = (shape.ref_tc_ms * 1e-3 * sr).max(1.0);
+        self.ref_alpha = 1.0 / ref_tc;
+        // Warm up over roughly one floor time constant, bounded so a huge rate
+        // cannot stall detection for long.
+        self.warmup = ref_tc.min(96_000.0) as u32;
+
+        self.delay = vec![Complex::new(0.0, 0.0); self.lookahead];
+        self.reset_state();
+    }
+
+    /// Clear streaming state without touching the derived parameters.
+    fn reset_state(&mut self) {
+        for s in self.delay.iter_mut() {
+            *s = Complex::new(0.0, 0.0);
         }
+        self.dpos = 0;
+        self.ref_sq = NB_MIN_REF;
+        self.seen = 0;
+        self.hold = 0;
+        self.gain = 1.0;
     }
 
     pub fn set_enabled(&mut self, enabled: bool) {
+        // Engaging fresh: drop any stale delayed samples and re-seed the floor.
+        if enabled && !self.enabled {
+            self.reset_state();
+        }
         self.enabled = enabled;
     }
 
@@ -53,7 +189,14 @@ impl NoiseBlanker {
         self.threshold = threshold.max(1.0);
     }
 
-    /// Process a block of IQ samples in-place, blanking impulse spikes.
+    pub fn set_profile(&mut self, profile: NoiseBlankerProfile) {
+        if profile != self.profile {
+            self.profile = profile;
+            self.recompute();
+        }
+    }
+
+    /// Process a block of IQ samples in-place, blanking impulse noise.
     pub fn process(&mut self, block: &mut [Complex<f32>]) {
         if !self.enabled || block.is_empty() {
             return;
@@ -62,17 +205,59 @@ impl NoiseBlanker {
         let thresh_sq = self.threshold * self.threshold;
 
         for sample in block.iter_mut() {
-            let s = *sample;
-            let mag_sq = s.re * s.re + s.im * s.im;
+            let x = *sample;
+            let mag_sq = x.re * x.re + x.im * x.im;
 
-            if mag_sq > thresh_sq * self.mean_sq {
-                // Impulse detected — replace with last clean sample.
-                *sample = self.last_clean;
+            // Look-ahead: emit the delayed sample, ingest the fresh one.
+            let y = if self.lookahead == 0 {
+                x
             } else {
-                // Clean sample — update RMS tracker.
-                self.mean_sq += NB_ALPHA * (mag_sq - self.mean_sq);
-                self.last_clean = s;
+                let out = self.delay[self.dpos];
+                self.delay[self.dpos] = x;
+                self.dpos += 1;
+                if self.dpos >= self.lookahead {
+                    self.dpos = 0;
+                }
+                out
+            };
+
+            // Seed the noise floor before trusting detection.
+            if self.seen < self.warmup {
+                self.seen += 1;
+                self.ref_sq += self.ref_alpha * (mag_sq - self.ref_sq);
+                if self.ref_sq < NB_MIN_REF {
+                    self.ref_sq = NB_MIN_REF;
+                }
+                *sample = y;
+                continue;
             }
+
+            // Detect on the fresh sample; it reaches the output `lookahead`
+            // samples later, by which time the gate has closed.
+            if mag_sq > thresh_sq * self.ref_sq {
+                self.hold = self.blank_samples;
+            } else if self.hold == 0 {
+                // Update the floor only from clean, passed samples.
+                self.ref_sq += self.ref_alpha * (mag_sq - self.ref_sq);
+                if self.ref_sq < NB_MIN_REF {
+                    self.ref_sq = NB_MIN_REF;
+                }
+            }
+
+            // Drive the gate toward its target and apply it to the output.
+            let target = if self.hold > 0 {
+                self.hold -= 1;
+                0.0
+            } else {
+                1.0
+            };
+            if self.gain < target {
+                self.gain = (self.gain + self.ramp_step).min(target);
+            } else if self.gain > target {
+                self.gain = (self.gain - self.ramp_step).max(target);
+            }
+
+            *sample = y * self.gain;
         }
     }
 }
@@ -81,6 +266,7 @@ impl NoiseBlanker {
 pub struct NoiseBlankerConfig {
     pub enabled: bool,
     pub threshold: f32,
+    pub profile: NoiseBlankerProfile,
 }
 
 impl Default for NoiseBlankerConfig {
@@ -88,6 +274,7 @@ impl Default for NoiseBlankerConfig {
         Self {
             enabled: false,
             threshold: 10.0,
+            profile: NoiseBlankerProfile::Spike,
         }
     }
 }
@@ -556,7 +743,7 @@ impl ChannelDsp {
             processing_enabled: true,
             force_mono_pcm,
             squelch: VirtualSquelch::new(squelch_cfg),
-            noise_blanker: NoiseBlanker::new(nb_cfg.enabled, nb_cfg.threshold),
+            noise_blanker: NoiseBlanker::new(nb_cfg, sdr_sample_rate),
             last_signal_db: -120.0,
             carrier_iq_power: 0.0,
             carrier_attack_alpha: Self::smeter_alphas(channel_sample_rate).0,
@@ -577,9 +764,15 @@ impl ChannelDsp {
         self.squelch.set_threshold_db(threshold_db);
     }
 
-    pub fn set_noise_blanker(&mut self, enabled: bool, threshold: f32) {
-        self.noise_blanker.set_enabled(enabled);
+    pub fn set_noise_blanker(
+        &mut self,
+        enabled: bool,
+        threshold: f32,
+        profile: NoiseBlankerProfile,
+    ) {
+        self.noise_blanker.set_profile(profile);
         self.noise_blanker.set_threshold(threshold);
+        self.noise_blanker.set_enabled(enabled);
     }
 
     pub fn set_mode(&mut self, mode: &RigMode) {
@@ -1046,30 +1239,89 @@ mod tests {
         assert_eq!(dsp.demodulator, Demodulator::Fm);
     }
 
+    fn nb_cfg(enabled: bool, threshold: f32, profile: NoiseBlankerProfile) -> NoiseBlankerConfig {
+        NoiseBlankerConfig {
+            enabled,
+            threshold,
+            profile,
+        }
+    }
+
+    /// Steady low-level signal, long enough to clear the warm-up window.
+    fn nb_warm(nb: &mut NoiseBlanker) {
+        let mut warm = vec![Complex::new(0.01, 0.01); 40_000];
+        nb.process(&mut warm);
+    }
+
     #[test]
     fn noise_blanker_suppresses_impulse() {
-        let mut nb = NoiseBlanker::new(true, 5.0);
-        // Feed a steady signal to establish the RMS baseline.
-        let mut block: Vec<Complex<f32>> = (0..256).map(|_| Complex::new(0.01, 0.01)).collect();
+        let sr = 1_000_000;
+        let mut nb = NoiseBlanker::new(nb_cfg(true, 5.0, NoiseBlankerProfile::Spike), sr);
+        nb_warm(&mut nb);
+
+        // One massive spike embedded in steady signal. With look-ahead the
+        // spike emerges at the output already gated, so *no* output sample may
+        // approach the raw spike power (200) — proving the leading edge did not
+        // leak through, which the old hold-based blanker allowed.
+        let mut block = vec![Complex::new(0.01, 0.01); 512];
+        block[200] = Complex::new(10.0, 10.0);
         nb.process(&mut block);
-        // Now inject a single massive spike at index 0.
-        let mut block2: Vec<Complex<f32>> = (0..256).map(|_| Complex::new(0.01, 0.01)).collect();
-        block2[0] = Complex::new(10.0, 10.0);
-        nb.process(&mut block2);
-        // The spike should have been blanked (replaced by last clean sample).
-        let mag = (block2[0].re * block2[0].re + block2[0].im * block2[0].im).sqrt();
+
+        let peak = block
+            .iter()
+            .map(|s| s.re * s.re + s.im * s.im)
+            .fold(0.0f32, f32::max);
+        assert!(peak < 1.0, "impulse leaked through, peak power {peak}");
+    }
+
+    #[test]
+    fn noise_blanker_passes_strong_steady_signal() {
+        // A strong *continuous* tone is not impulse noise: the floor tracks it,
+        // so the blanker must leave it essentially untouched rather than gating
+        // a real signal.
+        let sr = 1_000_000;
+        let mut nb = NoiseBlanker::new(nb_cfg(true, 5.0, NoiseBlankerProfile::Spike), sr);
+        let mut warm = vec![Complex::new(0.5, 0.5); 40_000];
+        nb.process(&mut warm);
+
+        let mut block = vec![Complex::new(0.5, 0.5); 512];
+        nb.process(&mut block);
+        // Tail of the block is past all transients and should pass at unity.
+        let tail = block[511];
         assert!(
-            mag < 1.0,
-            "expected impulse to be blanked, got magnitude {}",
-            mag
+            (tail.re - 0.5).abs() < 1e-3 && (tail.im - 0.5).abs() < 1e-3,
+            "steady signal was gated: {tail:?}"
         );
     }
 
     #[test]
     fn noise_blanker_disabled_passes_through() {
-        let mut nb = NoiseBlanker::new(false, 5.0);
+        let mut nb = NoiseBlanker::new(nb_cfg(false, 5.0, NoiseBlankerProfile::Spike), 1_000_000);
         let mut block = vec![Complex::new(10.0, 10.0); 4];
         nb.process(&mut block);
         assert_eq!(block[0], Complex::new(10.0, 10.0));
     }
+
+    #[test]
+    fn noise_blanker_wider_profile_blanks_longer() {
+        // A wider profile must hold the gate closed for more samples than a
+        // narrow one on the same impulse.
+        let sr = 1_000_000;
+        let count_blanked = |profile| {
+            let mut nb = NoiseBlanker::new(nb_cfg(true, 5.0, profile), sr);
+            nb_warm(&mut nb);
+            let mut block = vec![Complex::new(0.01, 0.01); 2048];
+            block[100] = Complex::new(10.0, 10.0);
+            nb.process(&mut block);
+            block
+                .iter()
+                .filter(|s| s.re * s.re + s.im * s.im < 1e-6)
+                .count()
+        };
+        assert!(
+            count_blanked(NoiseBlankerProfile::Broadband)
+                > count_blanked(NoiseBlankerProfile::Spike),
+            "broadband profile should blank a wider window than spike"
+        );
+    }
 }

src/trx-server/trx-backend/trx-backend-soapysdr/src/lib.rs

@@ -14,8 +14,8 @@ use std::sync::{Arc, Mutex};
 use trx_core::radio::freq::{Band, Freq};
 use trx_core::rig::response::RigError;
 use trx_core::rig::state::{
-    effective_demod_mode, DigSidebandPolicy, RigFilterState, SpectrumData, VchanRdsEntry,
-    WfmDenoiseLevel,
+    effective_demod_mode, DigSidebandPolicy, NoiseBlankerProfile, RigFilterState, SpectrumData,
+    VchanRdsEntry, WfmDenoiseLevel,
 };
 use trx_core::rig::{
     AudioSource, Rig, RigAccessMethod, RigCapabilities, RigCat, RigInfo, RigSdr, RigStatusFuture,
@@ -76,6 +76,8 @@ pub struct SoapySdrConfig {
     pub nb_enabled: bool,
     /// Noise blanker impulse threshold multiplier.
     pub nb_threshold: f64,
+    /// Noise blanker tuning profile (spike/ignition/powerline/broadband).
+    pub nb_profile: NoiseBlankerProfile,
     /// How DIG mode resolves to a sideband (auto/usb/lsb).
     pub dig_sideband: DigSidebandPolicy,
     /// FFT bin count for the spectrum display; a power of two.
@@ -109,6 +111,7 @@ impl Default for SoapySdrConfig {
             max_virtual_channels: 4,
             nb_enabled: false,
             nb_threshold: 10.0,
+            nb_profile: NoiseBlankerProfile::Spike,
             dig_sideband: DigSidebandPolicy::Auto,
             spectrum_fft_size: 1024,
         }
@@ -160,6 +163,8 @@ pub struct SoapySdrRig {
     nb_enabled: bool,
     /// Noise blanker impulse threshold multiplier.
     nb_threshold: f64,
+    /// Noise blanker tuning profile on the primary channel.
+    nb_profile: NoiseBlankerProfile,
     /// Hidden AIS decoder channels (A and B) when available.
     ais_channel_indices: Option<(usize, usize)>,
     /// Virtual channel manager shared with external consumers (e.g. RigHandle).
@@ -211,6 +216,7 @@ impl SoapySdrRig {
         let max_virtual_channels = config.max_virtual_channels;
         let nb_enabled = config.nb_enabled;
         let nb_threshold = config.nb_threshold;
+        let nb_profile = config.nb_profile;
         let dig_sideband = config.dig_sideband;
         let spectrum_fft_size = config.spectrum_fft_size;
         tracing::info!(
@@ -310,6 +316,7 @@ impl SoapySdrRig {
             dsp::NoiseBlankerConfig {
                 enabled: nb_enabled,
                 threshold: nb_threshold as f32,
+                profile: nb_profile,
             },
             &all_channels,
             spectrum_fft_size,
@@ -410,6 +417,7 @@ impl SoapySdrRig {
             squelch_threshold_db,
             nb_enabled,
             nb_threshold,
+            nb_profile,
             ais_channel_indices: Some((primary_channel_count, primary_channel_count + 1)),
             channel_manager,
             applied_primary_mode: initial_primary_mode.clone(),
@@ -478,6 +486,7 @@ impl SoapySdrRig {
             max_virtual_channels,
             nb_enabled,
             nb_threshold,
+            nb_profile: NoiseBlankerProfile::default(),
             dig_sideband: DigSidebandPolicy::default(),
         })
     }
@@ -985,6 +994,7 @@ impl RigSdr for SoapySdrRig {
         &'a mut self,
         enabled: bool,
         threshold: f64,
+        profile: NoiseBlankerProfile,
     ) -> Pin<Box<dyn std::future::Future<Output = DynResult<()>> + Send + 'a>> {
         Box::pin(async move {
             if !threshold.is_finite() {
@@ -995,13 +1005,14 @@ impl RigSdr for SoapySdrRig {
             }
             self.nb_enabled = enabled;
             self.nb_threshold = threshold;
+            self.nb_profile = profile;
             {
                 let dsps = self.pipeline.channel_dsps.read().unwrap();
                 if let Some(dsp_arc) = dsps.get(self.primary_channel_idx) {
                     dsp_arc
                         .lock()
                         .unwrap()
-                        .set_noise_blanker(enabled, threshold as f32);
+                        .set_noise_blanker(enabled, threshold as f32, profile);
                 }
             }
             Ok(())
@@ -1125,6 +1136,7 @@ impl RigSdr for SoapySdrRig {
             sdr_squelch_threshold_db: Some(self.squelch_threshold_db as f64),
             sdr_nb_enabled: Some(self.nb_enabled),
             sdr_nb_threshold: Some(self.nb_threshold),
+            sdr_nb_profile: Some(self.nb_profile),
             sdr_dig_sideband: Some(self.channel_manager.dig_policy()),
             wfm_deemphasis_us: self.wfm_deemphasis_us,
             wfm_stereo: self.wfm_stereo,