tune delay knobs

zephcore/app/CompanionMesh.cpp

@@ -1200,11 +1200,15 @@ uint32_t CompanionMesh::getRetransmitDelay(const mesh::Packet *packet)
 
 uint32_t CompanionMesh::getDirectRetransmitDelay(const mesh::Packet *packet)
 {
-	uint32_t t = _radio->getEstAirtimeFor(
+	uint32_t airtime = _radio->getEstAirtimeFor(
 		packet->getPathByteLen() + packet->payload_len + 2);
+	/* Jitter around Arduino direct factor 0.3 using a per-packet factor
+	 * in the range [0.25, 0.40]. */
+	uint32_t factor_milli = (uint32_t)getRNG()->nextInt(250, 401);
+	uint32_t max_jitter = (5 * airtime * factor_milli) / 1000;
 	/* Floor: give downstream nodes time to finish RX processing
 	 * and return to RX mode before we TX (~20ms settle + jitter) */
-	return 20 + getRNG()->nextInt(0, t / 10 + 1);
+	return 20 + getRNG()->nextInt(0, max_jitter + 1);
 }
 
 uint32_t CompanionMesh::getInitialFloodJitter(const mesh::Packet *packet)

zephcore/app/RepeaterDataStore.cpp

@@ -203,7 +203,7 @@ bool RepeaterDataStore::loadPrefs(NodePrefs& prefs) {
 
     /* Migrate uninitialized backoff_multiplier (0.0 or NaN) to default */
     if (prefs.backoff_multiplier == 0.0f || prefs.backoff_multiplier != prefs.backoff_multiplier) {
-        prefs.backoff_multiplier = 0.5f;
+        prefs.backoff_multiplier = 0.2f;
     }
 
     LOG_INF("Loaded prefs from %s", path);

zephcore/app/RepeaterMesh.cpp

@@ -571,11 +571,15 @@ uint32_t RepeaterMesh::getRetransmitDelay(const mesh::Packet* packet) {
 }
 
 uint32_t RepeaterMesh::getDirectRetransmitDelay(const mesh::Packet* packet) {
-    uint32_t t = _radio->getEstAirtimeFor(
+    uint32_t airtime = _radio->getEstAirtimeFor(
         packet->getPathByteLen() + packet->payload_len + 2);
+    /* Jitter around Arduino direct factor 0.3 using a per-packet factor
+     * in the range [0.25, 0.40]. */
+    uint32_t factor_milli = (uint32_t)getRNG()->nextInt(250, 401);
+    uint32_t max_jitter = (5 * airtime * factor_milli) / 1000;
     /* Floor: give downstream nodes time to finish RX processing
-     * and return to RX mode before we TX (~20ms settle + jitter) */
-    return 20 + getRNG()->nextInt(0, t / 10 + 1);
+     * and return to RX mode before we TX (~20ms settle + jitter). */
+    return 20 + getRNG()->nextInt(0, max_jitter + 1);
 }
 
 bool RepeaterMesh::filterRecvFloodPacket(mesh::Packet* pkt) {

zephcore/helpers/CommonCLI.cpp

@@ -124,12 +124,12 @@ void CommonCLI::loadPrefs(const char* path) {
     _prefs->rx_delay_base = constrain(_prefs->rx_delay_base, 0.0f, 20.0f);
     _prefs->tx_delay_factor = constrain(_prefs->tx_delay_factor, 0.0f, 2.0f);
     _prefs->direct_tx_delay_factor = constrain(_prefs->direct_tx_delay_factor, 0.0f, 2.0f);
-    /* Migrate uninitialized pad bytes: NaN or out-of-range → default 0.5.
+    /* Migrate uninitialized pad bytes: NaN or out-of-range → default 0.2.
      * 0.0 is valid (disables reactive backoff). Old firmware upgrading
      * with zeroed pad bytes will get 0.0 = disabled; user can set explicitly. */
     if (_prefs->backoff_multiplier != _prefs->backoff_multiplier ||
         _prefs->backoff_multiplier < 0.0f || _prefs->backoff_multiplier > 10.0f) {
-        _prefs->backoff_multiplier = 0.5f;
+        _prefs->backoff_multiplier = 0.2f;
     }
     _prefs->backoff_multiplier = constrain(_prefs->backoff_multiplier, 0.0f, 2.0f);
     /* Migrate old AF multiplier (0-9) to duty cycle percentage (0-99) */

zephcore/include/mesh/ContentionTracker.h

@@ -37,7 +37,7 @@ public:
 
 	float getContentionEstimate() const;
 
-	/* sqrt curve: MIN_FLOOD_FACTOR + FLOOD_SCALE * sqrt(est), cap 2.0.
+	/* Saturating curve: MIN + (MAX-MIN) * est/(est+HALFPOINT).
 	 * Returns 0.5 during warmup. */
 	float getFloodDelayFactor() const;
 
@@ -51,10 +51,10 @@ private:
 	static constexpr uint32_t WINDOW_MS = 10000;      /* dupe observation window; covers SF12 2-hop */
 	static constexpr int EMA_SHIFT = 3;               /* alpha = 1/8 */
 	static constexpr int WARMUP_PACKETS = 4;          /* min samples before EMA is trusted */
-	static constexpr float MIN_FLOOD_FACTOR = 0.05f;  /* floor: near-zero delay in quiet networks */
-	static constexpr float FLOOD_SCALE = 0.170f;      /* (0.5 - 0.05) / sqrt(15) */
-	static constexpr float MAX_FLOOD_FACTOR = 2.0f;   /* ceiling: 2x base airtime */
-	static constexpr float DEFAULT_BACKOFF_MULT = 0.5f; /* half-airtime per dupe heard */
+	static constexpr float MIN_FLOOD_FACTOR = 0.40f;  /* sparse mesh baseline */
+	static constexpr float MAX_FLOOD_FACTOR = 1.00f;  /* dense mesh ceiling */
+	static constexpr float FLOOD_EST_HALFPOINT = 4.0f; /* midpoint: factor=0.60 at est=4 */
+	static constexpr float DEFAULT_BACKOFF_MULT = 0.2f; /* airtime*0.2 per dupe heard */
 	static constexpr uint32_t REACTIVE_HARD_CAP_MS = 2000; /* max cumulative reactive extension */
 	static constexpr uint32_t STALE_MS = 300000;      /* 5 min: reset EMA if no traffic */
 

zephcore/src/ContentionTracker.cpp

@@ -5,7 +5,6 @@
 
 #include <mesh/ContentionTracker.h>
 #include <mesh/Packet.h>
-#include <math.h>
 #include <string.h>
 
 namespace mesh {
@@ -156,7 +155,10 @@ float ContentionTracker::getFloodDelayFactor() const
 	float est = getContentionEstimate();
 	if (est <= 0.0f) return MIN_FLOOD_FACTOR;
 
-	float factor = MIN_FLOOD_FACTOR + FLOOD_SCALE * sqrtf(est);
+	/* Arduino-like center near 0.5 in light contention, rising smoothly
+	 * toward 0.8 as contention increases. */
+	float factor = MIN_FLOOD_FACTOR + (MAX_FLOOD_FACTOR - MIN_FLOOD_FACTOR) *
+		       (est / (est + FLOOD_EST_HALFPOINT));
 	if (factor > MAX_FLOOD_FACTOR) factor = MAX_FLOOD_FACTOR;
 	return factor;
 }