From ec4ea28325bea912c4254146b1846ffcb31005d7 Mon Sep 17 00:00:00 2001
From: Armel FAUVEAU <armel.fauveau@globalis-ms.com>
Date: Sun, 3 May 2026 16:49:47 +0200
Subject: [PATCH] Reset fast scan RSSI floor on AM/FM changes

---
 App/app/chFrScanner.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/App/app/chFrScanner.c b/App/app/chFrScanner.c
index 3c755fc1..e03b28d1 100644
--- a/App/app/chFrScanner.c
+++ b/App/app/chFrScanner.c
@@ -98,6 +98,11 @@ static void ScanFastResetState(void)
     scanFastLastFullTuneCandidate = false;
 }
 
+static void ScanFastResetNoiseFloor(void)
+{
+    scanFastNoiseFloor = SCAN_FAST_RSSI_MAX;
+}
+
 static uint16_t ScanFastReadRssi(void)
 {
     uint8_t guard = SCAN_FAST_GLITCH_GUARD_MAX;
@@ -180,6 +185,15 @@ static void ScanFastApplyChannelShape(ModulationMode_t modulation)
         BK4819_SetFilterBandwidth(BK4819_FILTER_BW_WIDE, false);
 #endif
     }
+
+    if (modulationChanged)
+    {
+        // AM and FM use different demod/AGC profiles, so their RSSI
+        // baselines are not directly comparable. Relearn the floor after
+        // crossing that boundary instead of treating the next FM block as
+        // a wall of candidates.
+        ScanFastResetNoiseFloor();
+    }
 }
 #endif