[refactor](trx-server): remove fir_taps from SDR config and rig_task

Drop fir_taps field from SdrChannelConfig and its default. Remove the
SetFirTaps dispatch arm from rig_task. The DSP layer now auto-calculates
tap count from audio_bandwidth_hz.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-server/src/config.rs

@@ -382,8 +382,6 @@ pub struct SdrChannelConfig {
     pub mode: String,
     /// One-sided bandwidth of the post-demod audio BPF (Hz).
     pub audio_bandwidth_hz: u32,
-    /// FIR filter tap count. Higher = sharper roll-off. Default 64.
-    pub fir_taps: usize,
     /// CW tone centre frequency in the audio domain (Hz). Default 700.
     pub cw_center_hz: u32,
     /// Pre-demod bandwidth for WFM only (Hz). Default 75000.
@@ -403,7 +401,6 @@ impl Default for SdrChannelConfig {
             offset_hz: 0,
             mode: "auto".to_string(),
             audio_bandwidth_hz: 3000,
-            fir_taps: 64,
             cw_center_hz: 700,
             wfm_bandwidth_hz: 75_000,
             decoders: Vec::new(),

src/trx-server/src/main.rs

@@ -297,14 +297,14 @@ fn build_sdr_rig_from_instance(rig_cfg: &RigInstanceConfig) -> SdrRigBuildResult
     use trx_core::rig::AudioSource;
 
     let args = rig_cfg.rig.access.args.as_deref().unwrap_or("");
-    let mut channels: Vec<(f64, trx_core::rig::state::RigMode, u32, usize)> = rig_cfg
+    let mut channels: Vec<(f64, trx_core::rig::state::RigMode, u32)> = rig_cfg
         .sdr
         .channels
         .iter()
         .map(|ch| {
             let if_hz = (rig_cfg.sdr.center_offset_hz + ch.offset_hz) as f64;
             let mode = parse_rig_mode(&ch.mode, &rig_cfg.rig.initial_mode);
-            (if_hz, mode, ch.audio_bandwidth_hz, ch.fir_taps)
+            (if_hz, mode, ch.audio_bandwidth_hz)
         })
         .collect();
 
@@ -320,7 +320,6 @@ fn build_sdr_rig_from_instance(rig_cfg: &RigInstanceConfig) -> SdrRigBuildResult
             rig_cfg.sdr.center_offset_hz as f64,
             rig_cfg.rig.initial_mode.clone(),
             default_bw,
-            64,
         ));
     }
     let ais_channel_base_idx = channels.len();
@@ -359,7 +358,7 @@ fn build_sdr_rig_from_instance(rig_cfg: &RigInstanceConfig) -> SdrRigBuildResult
     // explicit VDES channel has been configured.
     let vdes_channel_idx = channels
         .iter()
-        .position(|(_, mode, _, _)| matches!(mode, trx_core::rig::state::RigMode::VDES))
+        .position(|(_, mode, _)| matches!(mode, trx_core::rig::state::RigMode::VDES))
         .unwrap_or(0);
     let vdes_iq = sdr_rig.subscribe_iq_channel(vdes_channel_idx);
     // Extract the virtual channel manager before the rig is consumed by Box.

src/trx-server/src/rig_task.rs

@@ -545,16 +545,6 @@ async fn process_command(
             let _ = ctx.state_tx.send(ctx.state.clone());
             return snapshot_from(ctx.state);
         }
-        RigCommand::SetFirTaps(taps) => {
-            if let Err(e) = ctx.rig.set_fir_taps(taps).await {
-                return Err(RigError::communication(format!("set_fir_taps: {e}")));
-            }
-            if let Some(f) = ctx.state.filter.as_mut() {
-                f.fir_taps = taps;
-            }
-            let _ = ctx.state_tx.send(ctx.state.clone());
-            return snapshot_from(ctx.state);
-        }
         RigCommand::SetSdrGain(gain_db) => {
             if let Err(e) = ctx.rig.set_sdr_gain(gain_db).await {
                 return Err(RigError::communication(format!("set_sdr_gain: {e}")));