From 5174e1ab73e8f6bc4e11480e8f17a45cea949e83 Mon Sep 17 00:00:00 2001
From: Stan Grams <sjg@haxx.space>
Date: Tue, 3 Mar 2026 01:07:00 +0100
Subject: [PATCH] [fix](trx-vdes): make burst detection more permissive

Lower the VDES burst detector thresholds further, shorten the minimum burst and end timing, and add a max-burst timeout so weak or continuous signals are more likely to finalize into diagnostic frames instead of staying invisible.

Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>
---
 src/decoders/trx-vdes/src/lib.rs | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/decoders/trx-vdes/src/lib.rs b/src/decoders/trx-vdes/src/lib.rs
index ad20527..7d6425f 100644
--- a/src/decoders/trx-vdes/src/lib.rs
+++ b/src/decoders/trx-vdes/src/lib.rs
@@ -20,8 +20,9 @@ use num_complex::Complex;
 use trx_core::decode::VdesMessage;
 
 const VDES_SYMBOL_RATE: f32 = 76_800.0;
-const MIN_BURST_MS: f32 = 2.0;
-const BURST_END_MS: f32 = 0.4;
+const MIN_BURST_MS: f32 = 0.8;
+const BURST_END_MS: f32 = 0.25;
+const MAX_BURST_MS: f32 = 45.0;
 const MIN_BURST_SYMBOLS: usize = 64;
 const TER_MCS1_100_BURST_SYMBOLS: usize = 1_984;
 const TER_MCS1_100_RAMP_SYMBOLS: usize = 32;
@@ -35,10 +36,10 @@ const TER_MCS1_100_SYNC_BITS: &[u8; TER_MCS1_100_SYNC_SYMBOLS] = b"1111110011010
 const PI4_QPSK_DIBITS: [u8; 4] = [0b00, 0b01, 0b11, 0b10];
 const MIN_SYNC_CANDIDATE_SCORE: f32 = 0.20;
 const MIN_SYNC_PARSE_SCORE: f32 = 0.50;
-const BURST_TRIGGER_NOISE_MULT: f32 = 4.0;
-const BURST_TRIGGER_FLOOR: f32 = 8.0e-5;
-const BURST_SUSTAIN_NOISE_MULT: f32 = 1.5;
-const BURST_SUSTAIN_FLOOR: f32 = 5.0e-5;
+const BURST_TRIGGER_NOISE_MULT: f32 = 1.8;
+const BURST_TRIGGER_FLOOR: f32 = 1.0e-6;
+const BURST_SUSTAIN_NOISE_MULT: f32 = 1.02;
+const BURST_SUSTAIN_FLOOR: f32 = 5.0e-7;
 
 #[derive(Debug, Clone)]
 pub struct VdesDecoder {
@@ -73,6 +74,8 @@ impl VdesDecoder {
             ((self.sample_rate * (MIN_BURST_MS / 1000.0)).round() as usize).max(16);
         let quiet_limit =
             ((self.sample_rate * (BURST_END_MS / 1000.0)).round() as u32).max(4);
+        let max_burst_samples =
+            ((self.sample_rate * (MAX_BURST_MS / 1000.0)).round() as usize).max(min_burst_samples);
 
         for &sample in samples {
             let power = sample.norm_sqr();
@@ -96,6 +99,16 @@ impl VdesDecoder {
                 self.quiet_run = 0;
             }
 
+            if self.burst_samples.len() >= max_burst_samples {
+                if let Some(msg) = self.finalize_burst(channel) {
+                    out.push(msg);
+                }
+                self.in_burst = false;
+                self.quiet_run = 0;
+                self.burst_samples.clear();
+                continue;
+            }
+
             if self.quiet_run >= quiet_limit {
                 if self.burst_samples.len() >= min_burst_samples {
                     if let Some(msg) = self.finalize_burst(channel) {