diff --git a/src/decoders/trx-ftx/src/common/decode.rs b/src/decoders/trx-ftx/src/common/decode.rs
index 640f131..560a3ad 100644
--- a/src/decoders/trx-ftx/src/common/decode.rs
+++ b/src/decoders/trx-ftx/src/common/decode.rs
@@ -49,16 +49,7 @@ pub(crate) fn get_cand_offset(wf: &Waterfall, cand: &Candidate) -> usize {
     offset.max(0) as usize
 }
 
-pub(crate) fn wf_mag_at(wf: &Waterfall, base: usize, idx: isize) -> &WfElem {
-    let i = (base as isize + idx).max(0) as usize;
-    if i < wf.mag.len() {
-        &wf.mag[i]
-    } else {
-        &DEFAULT_WF_ELEM
-    }
-}
-
-// Leaked reference for out-of-bounds default
+// Default element for out-of-bounds waterfall access
 pub(crate) static DEFAULT_WF_ELEM: WfElem = WfElem {
     mag: -120.0,
     phase: 0.0,
@@ -256,8 +247,8 @@ pub fn pack_bits(bit_array: &[u8], num_bits: usize, packed: &mut [u8]) {
     }
     let mut mask: u8 = 0x80;
     let mut byte_idx = 0;
-    for i in 0..num_bits {
-        if bit_array[i] != 0 {
+    for &bit in bit_array.iter().take(num_bits) {
+        if bit != 0 {
             packed[byte_idx] |= mask;
         }
         mask >>= 1;
@@ -312,19 +303,19 @@ pub fn ftx_post_decode_snr(wf: &Waterfall, cand: &Candidate, message: &FtxMessag
     let mut sum_snr = 0.0f32;
     let mut n_valid = 0;
 
-    for sym in 0..nn {
+    for (sym, &tone) in tones.iter().enumerate().take(nn) {
         let block_abs = cand.time_offset as i32 + sym as i32;
         if block_abs < 0 || block_abs >= wf.num_blocks as i32 {
             continue;
         }
 
         let p_offset = base + sym * wf.block_stride;
-        let sig_db = wf_mag_safe(wf, p_offset + tones[sym] as usize).mag;
+        let sig_db = wf_mag_safe(wf, p_offset + tone as usize).mag;
 
         let mut noise_min = 0.0f32;
         let mut found_noise = false;
         for t in 0..num_tones {
-            if t == tones[sym] as usize {
+            if t == tone as usize {
                 continue;
             }
             let db = wf_mag_safe(wf, p_offset + t).mag;
diff --git a/src/decoders/trx-ftx/src/common/encode.rs b/src/decoders/trx-ftx/src/common/encode.rs
index dee0f9f..c33adfa 100644
--- a/src/decoders/trx-ftx/src/common/encode.rs
+++ b/src/decoders/trx-ftx/src/common/encode.rs
@@ -33,10 +33,10 @@ pub(crate) fn encode174(message: &[u8], codeword: &mut [u8]) {
     let mut col_idx: usize = FTX_LDPC_K_BYTES - 1;
 
     // Compute the LDPC checksum bits and store them in codeword
-    for i in 0..FTX_LDPC_M {
+    for gen_row in FTX_LDPC_GENERATOR.iter().take(FTX_LDPC_M) {
         let mut nsum: u8 = 0;
         for j in 0..FTX_LDPC_K_BYTES {
-            nsum ^= parity8(message[j] & FTX_LDPC_GENERATOR[i][j]);
+            nsum ^= parity8(message[j] & gen_row[j]);
         }
 
         if !nsum.is_multiple_of(2) {
@@ -55,7 +55,7 @@ pub(crate) fn encode174(message: &[u8], codeword: &mut [u8]) {
 ///
 /// Each element of the returned array is 0 or 1.
 /// Uses the same (174, 91) LDPC generator as `encode174`.
-#[allow(dead_code)]
+#[cfg(test)]
 pub(crate) fn encode174_to_bits(a91: &[u8; FTX_LDPC_K_BYTES]) -> [u8; super::protocol::FTX_LDPC_N] {
     use super::protocol::FTX_LDPC_N;
     let mut codeword_packed = [0u8; FTX_LDPC_N_BYTES];
diff --git a/src/decoders/trx-ftx/src/common/message.rs b/src/decoders/trx-ftx/src/common/message.rs
index 45d2412..9ca0441 100644
--- a/src/decoders/trx-ftx/src/common/message.rs
+++ b/src/decoders/trx-ftx/src/common/message.rs
@@ -247,8 +247,7 @@ fn parse_cq_modifier(s: &str) -> Option<i32> {
     let mut nlet = 0;
     let mut m: i32 = 0;
 
-    for i in 3..8.min(bytes.len()) {
-        let c = bytes[i];
+    for &c in &bytes[3..8.min(bytes.len())] {
         if c == b' ' || c == 0 {
             break;
         } else if c.is_ascii_digit() {
@@ -511,16 +510,14 @@ fn pack58(hash_table: Option<&mut CallsignHashTable>, callsign: &str) -> Option<
 
     let mut result: u64 = 0;
     let mut c11 = String::with_capacity(12);
-    let mut length = 0;
 
-    for ch in src.chars() {
+    for (length, ch) in src.chars().enumerate() {
         if ch == '<' || length >= 11 {
             break;
         }
         c11.push(ch);
         let j = nchar(ch, CharTable::AlphanumSpaceSlash)?;
         result = result * 38 + j as u64;
-        length += 1;
     }
 
     save_callsign(hash_table, &c11)?;
@@ -1156,9 +1153,9 @@ pub fn ftx_message_decode_free(msg: &FtxMessage) -> String {
     for idx in (0..13).rev() {
         // Divide the long integer in b71 by 42
         let mut rem: u16 = 0;
-        for i in 0..9 {
-            rem = (rem << 8) | b71[i] as u16;
-            b71[i] = (rem / 42) as u8;
+        for b in &mut b71 {
+            rem = (rem << 8) | *b as u16;
+            *b = (rem / 42) as u8;
             rem %= 42;
         }
         c14[idx] = charn(rem as i32, CharTable::Full) as u8;
@@ -1183,9 +1180,9 @@ pub fn ftx_message_decode_telemetry_hex(msg: &FtxMessage) -> String {
 pub fn ftx_message_decode_telemetry(msg: &FtxMessage) -> [u8; 9] {
     let mut telemetry = [0u8; 9];
     let mut carry: u8 = 0;
-    for i in 0..9 {
-        telemetry[i] = (carry << 7) | (msg.payload[i] >> 1);
-        carry = msg.payload[i] & 0x01;
+    for (t, &p) in telemetry.iter_mut().zip(msg.payload.iter()) {
+        *t = (carry << 7) | (p >> 1);
+        carry = p & 0x01;
     }
     telemetry
 }
diff --git a/src/decoders/trx-ftx/src/common/mod.rs b/src/decoders/trx-ftx/src/common/mod.rs
index afddaef..e157918 100644
--- a/src/decoders/trx-ftx/src/common/mod.rs
+++ b/src/decoders/trx-ftx/src/common/mod.rs
@@ -7,17 +7,11 @@
 pub mod callsign_hash;
 pub mod constants;
 pub mod crc;
-#[allow(dead_code, clippy::needless_range_loop)]
 pub mod decode;
-#[allow(clippy::needless_range_loop)]
 pub mod encode;
-#[allow(clippy::needless_range_loop)]
 pub mod ldpc;
-#[allow(clippy::explicit_counter_loop, clippy::needless_range_loop)]
 pub mod message;
-#[allow(dead_code)]
 pub mod monitor;
-#[allow(dead_code, clippy::needless_range_loop, clippy::too_many_arguments)]
 pub mod osd;
 pub mod protocol;
 pub mod text;
diff --git a/src/decoders/trx-ftx/src/common/monitor.rs b/src/decoders/trx-ftx/src/common/monitor.rs
index 225678c..e324567 100644
--- a/src/decoders/trx-ftx/src/common/monitor.rs
+++ b/src/decoders/trx-ftx/src/common/monitor.rs
@@ -8,7 +8,6 @@
 
 use num_complex::Complex32;
 use realfft::RealFftPlanner;
-use rustfft::FftPlanner;
 
 use super::protocol::FtxProtocol;
 
@@ -94,10 +93,6 @@ pub struct Monitor {
     fft_output: Vec<Complex32>,
     fft_input: Vec<f32>,
     real_fft: std::sync::Arc<dyn realfft::RealToComplex<f32>>,
-    // iFFT for resynthesis
-    nifft: usize,
-    ifft: std::sync::Arc<dyn rustfft::Fft<f32>>,
-    ifft_scratch: Vec<Complex32>,
 }
 
 fn hann_i(i: usize, n: usize) -> f32 {
@@ -137,11 +132,6 @@ impl Monitor {
         let fft_output = real_fft.make_output_vec();
         let fft_input = real_fft.make_input_vec();
 
-        let nifft = 64;
-        let mut fft_planner = FftPlanner::<f32>::new();
-        let ifft = fft_planner.plan_fft_inverse(nifft);
-        let ifft_scratch = vec![Complex32::new(0.0, 0.0); ifft.get_inplace_scratch_len()];
-
         Self {
             symbol_period,
             min_bin,
@@ -158,9 +148,6 @@ impl Monitor {
             fft_output,
             fft_input,
             real_fft,
-            nifft,
-            ifft,
-            ifft_scratch,
         }
     }
 
diff --git a/src/decoders/trx-ftx/src/common/osd.rs b/src/decoders/trx-ftx/src/common/osd.rs
index 23a28e6..6f9393d 100644
--- a/src/decoders/trx-ftx/src/common/osd.rs
+++ b/src/decoders/trx-ftx/src/common/osd.rs
@@ -76,14 +76,6 @@ fn encode174_91_nocrc_bits(message91: &[u8], codeword: &mut [u8; FTX_LDPC_N]) {
     }
 }
 
-/// XOR two byte slices.
-fn xor_rows(dst: &mut [u8], src: &[u8], len: usize) {
-    dst[..len]
-        .iter_mut()
-        .zip(&src[..len])
-        .for_each(|(d, s)| *d ^= s);
-}
-
 /// Matrix-vector multiply for re-encoding in OSD.
 fn mrbencode91(me: &[u8], codeword: &mut [u8], g2: &[u8], n: usize, k: usize) {
     codeword[..n].fill(0);
@@ -114,24 +106,20 @@ fn nextpat91(mi: &mut [u8], k: usize, iorder: usize, iflag: &mut i32) {
 
     // Build new pattern in-place: zero out after ind, set the swap, pack remaining 1s at end
     let ind_u = ind as usize;
-    for i in (ind_u + 1)..k {
-        mi[i] = 0;
-    }
+    mi[(ind_u + 1)..k].fill(0);
     mi[ind_u] = 1;
 
     let mut nz = iorder as i32;
-    for i in 0..k {
-        nz -= mi[i] as i32;
+    for &v in mi.iter().take(k) {
+        nz -= v as i32;
     }
     if nz > 0 {
-        for i in (k - nz as usize)..k {
-            mi[i] = 1;
-        }
+        mi[(k - nz as usize)..k].fill(1);
     }
 
     *iflag = -1;
-    for i in 0..k {
-        if mi[i] == 1 {
+    for (i, &v) in mi.iter().enumerate().take(k) {
+        if v == 1 {
             *iflag = i as i32;
             break;
         }
@@ -145,7 +133,6 @@ struct OsdBox {
     pairs: Vec<[i32; 2]>,
     capacity: usize,
     count: usize,
-    size: usize,
     last_pattern: i32,
     next_index: i32,
 }
@@ -160,7 +147,6 @@ impl OsdBox {
             pairs: vec![[-1, -1]; capacity],
             capacity,
             count: 0,
-            size,
             last_pattern: -1,
             next_index: -1,
         })
@@ -214,8 +200,8 @@ impl OsdBox {
 /// Compute hash of a bit pattern for OSD-2 lookup.
 fn pattern_hash(e2: &[u8], ntau: usize) -> usize {
     let mut ipat = 0usize;
-    for i in 0..ntau {
-        if e2[i] != 0 {
+    for (i, &v) in e2.iter().enumerate().take(ntau) {
+        if v != 0 {
             ipat |= 1 << (ntau - i - 1);
         }
     }
@@ -232,6 +218,7 @@ fn pattern_hash(e2: &[u8], ntau: usize) -> usize {
 /// `cw`: output 174-bit codeword.
 /// `nhardmin`: output minimum hard errors.
 /// `dmin`: output minimum distance.
+#[allow(clippy::too_many_arguments)]
 pub fn osd174_91(
     llr: &mut [f32; FTX_LDPC_N],
     k: usize,
@@ -372,9 +359,7 @@ pub fn osd174_91(
     // OSD-1: exhaustive search over bit patterns of increasing order
     for iorder in 1..=nord {
         misub.iter_mut().for_each(|v| *v = 0);
-        for i in (k - iorder)..k {
-            misub[i] = 1;
-        }
+        misub[(k - iorder)..k].fill(1);
         let mut iflag = (k - iorder) as i32;
 
         while iflag >= 0 {
@@ -408,8 +393,8 @@ pub fn osd174_91(
                         e2[i] = e2sub[i];
                     }
                     let mut nd1kpt = 1;
-                    for i in 0..nt.min(n - k) {
-                        nd1kpt += e2sub[i] as i32;
+                    for &v in e2sub.iter().take(nt.min(n - k)) {
+                        nd1kpt += v as i32;
                     }
                     d1 = 0.0;
                     for i in 0..k {
@@ -438,8 +423,8 @@ pub fn osd174_91(
                         e2[i] = e2sub[i] ^ g2[(k + i) * k + n1 as usize];
                     }
                     let mut nd1kpt = 2;
-                    for i in 0..nt.min(n - k) {
-                        nd1kpt += e2[i] as i32;
+                    for &v in e2.iter().take(nt.min(n - k)) {
+                        nd1kpt += v as i32;
                     }
                     if nd1kpt <= ntheta {
                         mrbencode91(&me, &mut ce, &g2, n, k);
@@ -486,9 +471,7 @@ pub fn osd174_91(
 
             // Search using base patterns
             misub.iter_mut().for_each(|v| *v = 0);
-            for i in (k - nord)..k {
-                misub[i] = 1;
-            }
+            misub[(k - nord)..k].fill(1);
             let mut iflag = (k - nord) as i32;
 
             while iflag >= 0 {
@@ -594,9 +577,7 @@ fn generator_matrix() -> &'static [[u8; FTX_LDPC_N]; FTX_LDPC_K] {
             let mut msg = [0u8; FTX_LDPC_K];
             msg[i] = 1;
             if i < 77 {
-                for j in 77..FTX_LDPC_K {
-                    msg[j] = 0;
-                }
+                msg[77..FTX_LDPC_K].fill(0);
             }
             encode174_91_nocrc_bits(&msg, &mut gen[i]);
         }
@@ -620,6 +601,7 @@ fn generator_matrix() -> &'static [[u8; FTX_LDPC_N]; FTX_LDPC_K] {
 /// `ntype`: output decode type (0=fail, 1=BP, 2=OSD).
 /// `nharderror`: output number of hard errors.
 /// `dmin`: output minimum distance.
+#[allow(clippy::too_many_arguments)]
 pub fn ft2_decode174_91_osd(
     llr: &mut [f32; FTX_LDPC_N],
     keff: usize,
@@ -732,8 +714,8 @@ pub fn ft2_decode174_91_osd(
             for i in 0..num_rows.min(7) {
                 tanhtoc[i] = (-toc[m][i] / 2.0).tanh();
             }
-            for j in 0..num_rows {
-                let n = FTX_LDPC_NM[m][j] as usize - 1;
+            for &nm_val in FTX_LDPC_NM[m].iter().take(num_rows) {
+                let n = nm_val as usize - 1;
                 if n >= FTX_LDPC_N {
                     continue;
                 }
diff --git a/src/decoders/trx-ftx/src/ft2/bitmetrics.rs b/src/decoders/trx-ftx/src/ft2/bitmetrics.rs
index f9d5ac9..779ae08 100644
--- a/src/decoders/trx-ftx/src/ft2/bitmetrics.rs
+++ b/src/decoders/trx-ftx/src/ft2/bitmetrics.rs
@@ -78,9 +78,9 @@ impl BitMetricsWorkspace {
 
         // Sync quality check: verify Costas patterns are detectable
         let mut sync_ok = 0;
-        for group in 0..4 {
+        for (group, costas_group) in FT4_COSTAS_PATTERN.iter().enumerate() {
             let base = group * 33;
-            for i in 0..4 {
+            for (i, &costas_tone) in costas_group.iter().enumerate() {
                 if base + i >= FT2_FRAME_SYMBOLS {
                     continue;
                 }
@@ -90,7 +90,7 @@ impl BitMetricsWorkspace {
                         best = tone;
                     }
                 }
-                if best == FT4_COSTAS_PATTERN[group][i] as usize {
+                if best == costas_tone as usize {
                     sync_ok += 1;
                 }
             }
diff --git a/src/decoders/trx-ftx/src/ft2/decode.rs b/src/decoders/trx-ftx/src/ft2/decode.rs
index 2c98f1e..15d396f 100644
--- a/src/decoders/trx-ftx/src/ft2/decode.rs
+++ b/src/decoders/trx-ftx/src/ft2/decode.rs
@@ -17,10 +17,10 @@ pub(crate) fn ft2_sync_score(wf: &Waterfall, cand: &Candidate) -> i32 {
     let mut score_f: f32 = 0.0;
     let mut groups = 0;
 
-    for m in 0..FT2_NUM_SYNC {
+    for (m, costas_group) in FT4_COSTAS_PATTERN.iter().enumerate().take(FT2_NUM_SYNC) {
         let mut sum = Complex32::new(0.0, 0.0);
         let mut complete = true;
-        for k in 0..FT2_LENGTH_SYNC {
+        for (k, &costas_tone) in costas_group.iter().enumerate().take(FT2_LENGTH_SYNC) {
             let block = 1 + FT2_SYNC_OFFSET * m + k;
             let block_abs = cand.time_offset as i32 + block as i32;
             if block_abs < 0 || block_abs >= wf.num_blocks as i32 {
@@ -28,7 +28,7 @@ pub(crate) fn ft2_sync_score(wf: &Waterfall, cand: &Candidate) -> i32 {
                 break;
             }
             let sym_offset = base + block * wf.block_stride;
-            let tone = FT4_COSTAS_PATTERN[m][k] as usize;
+            let tone = costas_tone as usize;
             let elem = *wf_mag_safe(wf, sym_offset + tone);
             sum += wf_elem_to_complex(elem);
         }
@@ -63,9 +63,9 @@ pub(crate) fn ft2_extract_likelihood(
             continue;
         }
         let sym_offset = base + sym_idx * wf.block_stride;
-        for tone in 0..4 {
+        for (tone, symbol_row) in symbols.iter_mut().enumerate().take(4) {
             let elem = *wf_mag_safe(wf, sym_offset + tone);
-            symbols[tone][frame_sym] = wf_elem_to_complex(elem);
+            symbol_row[frame_sym] = wf_elem_to_complex(elem);
         }
     }
 
diff --git a/src/decoders/trx-ftx/src/ft2/downsample.rs b/src/decoders/trx-ftx/src/ft2/downsample.rs
index e92a528..2a8b9f4 100644
--- a/src/decoders/trx-ftx/src/ft2/downsample.rs
+++ b/src/decoders/trx-ftx/src/ft2/downsample.rs
@@ -190,8 +190,8 @@ impl DownsampleContext {
         }
 
         // Apply spectral window
-        for i in 0..self.nfft2 {
-            band[i] *= self.window[i];
+        for (b, &w) in band.iter_mut().zip(self.window.iter()) {
+            *b *= w;
         }
 
         // Inverse FFT (in-place)
@@ -221,19 +221,27 @@ fn build_spectral_window(nfft2: usize, df: f32) -> Vec<f32> {
     }
 
     // Raised-cosine leading edge
-    for i in 0..iwt.min(nfft2) {
-        window[i] = 0.5 * (1.0 + (std::f32::consts::PI * (iwt - 1 - i) as f32 / iwt as f32).cos());
+    for (i, w) in window.iter_mut().enumerate().take(iwt.min(nfft2)) {
+        *w = 0.5 * (1.0 + (std::f32::consts::PI * (iwt - 1 - i) as f32 / iwt as f32).cos());
     }
 
     // Flat passband
-    for i in iwt..(iwt + iwf).min(nfft2) {
-        window[i] = 1.0;
+    for w in window
+        .iter_mut()
+        .skip(iwt)
+        .take((iwt + iwf).min(nfft2) - iwt)
+    {
+        *w = 1.0;
     }
 
     // Raised-cosine trailing edge
-    for i in (iwt + iwf)..(2 * iwt + iwf).min(nfft2) {
-        window[i] =
-            0.5 * (1.0 + (std::f32::consts::PI * (i - (iwt + iwf)) as f32 / iwt as f32).cos());
+    for (i, w) in window
+        .iter_mut()
+        .enumerate()
+        .take((2 * iwt + iwf).min(nfft2))
+        .skip(iwt + iwf)
+    {
+        *w = 0.5 * (1.0 + (std::f32::consts::PI * (i - (iwt + iwf)) as f32 / iwt as f32).cos());
     }
 
     // Circular shift by iws bins
diff --git a/src/decoders/trx-ftx/src/ft2/mod.rs b/src/decoders/trx-ftx/src/ft2/mod.rs
index 73f565b..19c7ade 100644
--- a/src/decoders/trx-ftx/src/ft2/mod.rs
+++ b/src/decoders/trx-ftx/src/ft2/mod.rs
@@ -8,12 +8,9 @@
 //! peaks in the averaged spectrum, downsample each candidate, compute 2D sync
 //! scores, extract bit metrics, and run multi-pass LDPC + OSD decode.
 
-#[allow(clippy::needless_range_loop)]
 pub mod bitmetrics;
 pub(crate) mod decode;
-#[allow(clippy::needless_range_loop)]
 pub mod downsample;
-#[allow(clippy::needless_range_loop)]
 pub mod sync;
 
 pub(crate) use self::decode::{ft2_extract_likelihood, ft2_sync_score};
@@ -50,6 +47,13 @@ pub fn ft2_frequency_offset_hz() -> f32 {
     -1.5 / FT2_SYMBOL_PERIOD_F
 }
 
+/// Generate FT2 tone sequence from payload data.
+///
+/// FT2 uses the FT4 framing with a doubled symbol rate.
+pub fn ft2_encode(payload: &[u8], tones: &mut [u8]) {
+    crate::ft4::ft4_encode(payload, tones);
+}
+
 /// Raw frequency peak candidate from the averaged power spectrum.
 #[derive(Clone, Copy, Default)]
 pub struct RawCandidate {
@@ -315,8 +319,8 @@ impl Ft2Pipeline {
         }
 
         let inv_n_frames = 1.0 / n_frames as f32;
-        for bin in 1..FT2_NH1 {
-            avg[bin] *= inv_n_frames;
+        for v in avg.iter_mut().take(FT2_NH1).skip(1) {
+            *v *= inv_n_frames;
         }
 
         // Smooth with 15-point moving average
@@ -620,17 +624,24 @@ impl Ft2Pipeline {
         }
 
         // Scale and derive combined passes
-        for i in 0..FTX_LDPC_N {
-            llr_passes[0][i] *= 2.83;
-            llr_passes[1][i] *= 2.83;
-            llr_passes[2][i] *= 2.83;
-
-            let a = llr_passes[0][i];
-            let b = llr_passes[1][i];
-            let c = llr_passes[2][i];
-
+        let [ref mut pass0, ref mut pass1, ref mut pass2, ref mut pass3, ref mut pass4] =
+            llr_passes;
+        for v in pass0.iter_mut() {
+            *v *= 2.83;
+        }
+        for v in pass1.iter_mut() {
+            *v *= 2.83;
+        }
+        for v in pass2.iter_mut() {
+            *v *= 2.83;
+        }
+        for ((&a, &b), (&c, (p3, p4))) in pass0
+            .iter()
+            .zip(pass1.iter())
+            .zip(pass2.iter().zip(pass3.iter_mut().zip(pass4.iter_mut())))
+        {
             // Pass 3: max-abs metric
-            llr_passes[3][i] = if a.abs() >= b.abs() && a.abs() >= c.abs() {
+            *p3 = if a.abs() >= b.abs() && a.abs() >= c.abs() {
                 a
             } else if b.abs() >= c.abs() {
                 b
@@ -639,7 +650,7 @@ impl Ft2Pipeline {
             };
 
             // Pass 4: average
-            llr_passes[4][i] = (a + b + c) / 3.0;
+            *p4 = (a + b + c) / 3.0;
         }
 
         // Multi-pass LDPC decode using full BP+OSD decoder
@@ -647,11 +658,11 @@ impl Ft2Pipeline {
         let mut message = FtxMessage::default();
         let mut apmask = [0u8; FTX_LDPC_N];
 
-        for pass in 0..5 {
+        for llr_pass in &llr_passes {
             if ok {
                 break;
             }
-            let mut log174 = llr_passes[pass];
+            let mut log174 = *llr_pass;
 
             let mut message91 = [0u8; FTX_LDPC_K];
             let mut cw = [0u8; FTX_LDPC_N];
@@ -822,4 +833,14 @@ mod tests {
             assert_eq!(b, 0);
         }
     }
+
+    #[test]
+    fn ft2_encode_matches_ft4() {
+        let payload = [0x12, 0x34, 0x56, 0x78, 0x9A, 0xBC, 0xDE, 0xF0, 0x11, 0x20];
+        let mut tones_ft4 = [0u8; FT4_NN];
+        let mut tones_ft2 = [0u8; FT4_NN];
+        crate::ft4::ft4_encode(&payload, &mut tones_ft4);
+        ft2_encode(&payload, &mut tones_ft2);
+        assert_eq!(tones_ft4, tones_ft2);
+    }
 }
diff --git a/src/decoders/trx-ftx/src/ft2/sync.rs b/src/decoders/trx-ftx/src/ft2/sync.rs
index 447d99d..407f15d 100644
--- a/src/decoders/trx-ftx/src/ft2/sync.rs
+++ b/src/decoders/trx-ftx/src/ft2/sync.rs
@@ -50,8 +50,8 @@ pub fn prepare_sync_waveforms() -> SyncWaveforms {
     for group in 0..4 {
         let mut idx = 0usize;
         let mut phase = 0.0f32;
-        for tone_idx in 0..4 {
-            let tone = FT4_COSTAS_PATTERN[group][tone_idx] as f32;
+        for &costas_tone in FT4_COSTAS_PATTERN[group].iter() {
+            let tone = costas_tone as f32;
             let dphase = 4.0 * std::f32::consts::PI * tone / nss;
             let half_nss = (nss / 2.0) as usize;
             for _step in 0..half_nss {
@@ -68,9 +68,9 @@ pub fn prepare_sync_waveforms() -> SyncWaveforms {
     // Build frequency tweak phasors
     for idf in FT2_SYNC_TWEAK_MIN..=FT2_SYNC_TWEAK_MAX {
         let tw_idx = (idf - FT2_SYNC_TWEAK_MIN) as usize;
-        for n in 0..64 {
+        for (n, tw) in tweak_wave[tw_idx].iter_mut().enumerate() {
             let phase = 4.0 * std::f32::consts::PI * idf as f32 * n as f32 / fs_down;
-            tweak_wave[tw_idx][n] = Complex32::new(phase.cos(), phase.sin());
+            *tw = Complex32::new(phase.cos(), phase.sin());
         }
     }
 
@@ -89,11 +89,10 @@ fn sync_reference_bank() -> &'static SyncReferenceBank {
         let waveforms = prepare_sync_waveforms();
         let mut refs = [[[Complex32::new(0.0, 0.0); SYNC_SAMPLES]; SYNC_GROUP_COUNT]; NUM_TWEAKS];
 
-        for tw_idx in 0..NUM_TWEAKS {
-            for group in 0..SYNC_GROUP_COUNT {
-                for i in 0..SYNC_SAMPLES {
-                    refs[tw_idx][group][i] =
-                        (waveforms.sync_wave[group][i] * waveforms.tweak_wave[tw_idx][i]).conj();
+        for (tw_idx, refs_tw) in refs.iter_mut().enumerate() {
+            for (group, refs_group) in refs_tw.iter_mut().enumerate() {
+                for (i, r) in refs_group.iter_mut().enumerate() {
+                    *r = (waveforms.sync_wave[group][i] * waveforms.tweak_wave[tw_idx][i]).conj();
                 }
             }
         }
@@ -132,14 +131,13 @@ fn correlate_group_clipped(
     let mut usable = 0usize;
     let n_samples = samples.len() as i32;
 
-    for i in 0..SYNC_SAMPLES {
+    for (i, &reference) in refs.iter().enumerate() {
         let sample_idx = pos + i as i32 * SAMPLE_STRIDE as i32;
         if sample_idx < 0 || sample_idx >= n_samples {
             continue;
         }
 
         let sample = samples[sample_idx as usize];
-        let reference = refs[i];
         sum_re += sample.re * reference.re - sample.im * reference.im;
         sum_im += sample.re * reference.im + sample.im * reference.re;
         usable += 1;
diff --git a/src/decoders/trx-ftx/src/ft4/mod.rs b/src/decoders/trx-ftx/src/ft4/mod.rs
index 1ce0f9c..9ef5139 100644
--- a/src/decoders/trx-ftx/src/ft4/mod.rs
+++ b/src/decoders/trx-ftx/src/ft4/mod.rs
@@ -17,8 +17,8 @@ pub(crate) fn ft4_sync_score(wf: &Waterfall, cand: &Candidate) -> i32 {
     let mut score: i32 = 0;
     let mut num_average: i32 = 0;
 
-    for m in 0..FT4_NUM_SYNC {
-        for k in 0..FT4_LENGTH_SYNC {
+    for (m, costas_group) in FT4_COSTAS_PATTERN.iter().enumerate().take(FT4_NUM_SYNC) {
+        for (k, &sm_val) in costas_group.iter().enumerate().take(FT4_LENGTH_SYNC) {
             let block = 1 + FT4_SYNC_OFFSET * m + k;
             let block_abs = cand.time_offset as i32 + block as i32;
             if block_abs < 0 {
@@ -29,7 +29,7 @@ pub(crate) fn ft4_sync_score(wf: &Waterfall, cand: &Candidate) -> i32 {
             }
 
             let p_offset = base + block * wf.block_stride;
-            let sm = FT4_COSTAS_PATTERN[m][k] as usize;
+            let sm = sm_val as usize;
 
             if sm > 0 {
                 let a = wf_mag_safe(wf, p_offset + sm).mag_int();
@@ -174,13 +174,6 @@ pub fn ft4_encode(payload: &[u8], tones: &mut [u8]) {
     }
 }
 
-/// Generate FT2 tone sequence from payload data.
-///
-/// FT2 uses the FT4 framing with a doubled symbol rate.
-pub fn ft2_encode(payload: &[u8], tones: &mut [u8]) {
-    ft4_encode(payload, tones);
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -244,14 +237,4 @@ mod tests {
         ft4_encode(&payload, &mut tones2);
         assert_eq!(tones1, tones2);
     }
-
-    #[test]
-    fn ft2_encode_matches_ft4() {
-        let payload = [0x12, 0x34, 0x56, 0x78, 0x9A, 0xBC, 0xDE, 0xF0, 0x11, 0x20];
-        let mut tones_ft4 = [0u8; FT4_NN];
-        let mut tones_ft2 = [0u8; FT4_NN];
-        ft4_encode(&payload, &mut tones_ft4);
-        ft2_encode(&payload, &mut tones_ft2);
-        assert_eq!(tones_ft4, tones_ft2);
-    }
 }
diff --git a/src/decoders/trx-ftx/src/ft8/mod.rs b/src/decoders/trx-ftx/src/ft8/mod.rs
index e923c6f..ce792a4 100644
--- a/src/decoders/trx-ftx/src/ft8/mod.rs
+++ b/src/decoders/trx-ftx/src/ft8/mod.rs
@@ -18,7 +18,7 @@ pub(crate) fn ft8_sync_score(wf: &Waterfall, cand: &Candidate) -> i32 {
     let mut num_average: i32 = 0;
 
     for m in 0..FT8_NUM_SYNC {
-        for k in 0..FT8_LENGTH_SYNC {
+        for (k, &sm_val) in FT8_COSTAS_PATTERN.iter().enumerate().take(FT8_LENGTH_SYNC) {
             let block = FT8_SYNC_OFFSET * m + k;
             let block_abs = cand.time_offset as i32 + block as i32;
             if block_abs < 0 {
@@ -29,7 +29,7 @@ pub(crate) fn ft8_sync_score(wf: &Waterfall, cand: &Candidate) -> i32 {
             }
 
             let p_offset = base + block * wf.block_stride;
-            let sm = FT8_COSTAS_PATTERN[k] as usize;
+            let sm = sm_val as usize;
 
             if sm > 0 {
                 let a = wf_mag_safe(wf, p_offset + sm).mag_int();
diff --git a/src/decoders/trx-ftx/src/lib.rs b/src/decoders/trx-ftx/src/lib.rs
index 2d3d17c..0e2b488 100644
--- a/src/decoders/trx-ftx/src/lib.rs
+++ b/src/decoders/trx-ftx/src/lib.rs
@@ -4,11 +4,8 @@
 
 pub mod common;
 mod decoder;
-#[allow(clippy::needless_range_loop)]
 pub mod ft2;
-#[allow(clippy::needless_range_loop)]
 pub mod ft4;
-#[allow(clippy::needless_range_loop)]
 pub mod ft8;
 
 pub use decoder::{Ft8DecodeResult, Ft8Decoder};