From 3843c00f54ba1d977accc7b037bb409296238833 Mon Sep 17 00:00:00 2001
From: overkillfpv <t.hitchins@exemail.com.au>
Date: Tue, 24 Mar 2026 15:05:15 +1100
Subject: [PATCH] added the preamble update into get est airtime as a
 prevention for false airtime calcs. Left update in the startsendraw as a
 safety, but should not be used under normal circumstances

---
 src/helpers/radiolib/RadioLibWrappers.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/helpers/radiolib/RadioLibWrappers.cpp b/src/helpers/radiolib/RadioLibWrappers.cpp
index 18251e43..cc1dc001 100644
--- a/src/helpers/radiolib/RadioLibWrappers.cpp
+++ b/src/helpers/radiolib/RadioLibWrappers.cpp
@@ -139,6 +139,11 @@ int RadioLibWrapper::recvRaw(uint8_t* bytes, int sz) {
 }
 
 uint32_t RadioLibWrapper::getEstAirtimeFor(int len_bytes) {
+  uint8_t sf = getSpreadingFactor();
+  if (sf != _preamble_sf) {
+    _preamble_sf = sf;
+    _radio->setPreambleLength(preambleLengthForSF(sf)); // sync preamble before airtime estimate
+  }
   return _radio->getTimeOnAir(len_bytes) / 1000;
 }