Noise floor (#9347)

* add noise floor

* Sliding window noise floor

* Add getCurrentRSSI() to SimRadio for noise floor support

* Remove sendLocalStatsToPhone call from runOnce

* Change noise floor to int32_t type

* Use int32_t for RSSI sample storage in noise floor

* Remove float cast from noise floor assignment

* Fix Copilot review issues: fix noise floor logic, types, and null pointer

- Use robust busyTx/busyRx checks instead of simple isReceiving check
- Initialize noiseFloorSamples to NOISE_FLOOR_MIN instead of 0
- Move noise_floor assignment inside null check to prevent potential crash
- Change getNoiseFloor() and getAverageNoiseFloor() to return int32_t
- Fix RSSI validation to check for positive values (rssi > 0)
- Fix format specifier from %.1f to %d for int32_t
- Update comments to accurately reflect the sampling logic

* Fix RSSI condition to include zero value

* Change noise floor initialization to zero

* Disable noise floor for LR11x0 chips: getRSSI(bool) unsupported

* Remove updateNoiseFloor call from onNotify to avoid radio queue overflow

Per PR review feedback, calling updateNoiseFloor() in onNotify() for every
ISR event (ISR_TX, ISR_RX, TRANSMIT_DELAY_COMPLETED) can cause the LoRa
radio queue to get full. The noise floor sampling still happens in
startReceive() and after transmitting.

* fix lr11x0 current rssi

* Address noise floor review comments

* Address Copilot SimRadio noise floor comments

* Fix RadioLibInterface formatting

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>

src/mesh/RadioLibInterface.cpp

@@ -15,6 +15,7 @@
 #include "PortduinoGlue.h"
 #include "meshUtils.h"
 #endif
+
 void LockingArduinoHal::spiBeginTransaction()
 {
     spiLock->lock();
@@ -28,6 +29,7 @@ void LockingArduinoHal::spiEndTransaction()
 
     spiLock->unlock();
 }
+
 #if ARCH_PORTDUINO
 void LockingArduinoHal::spiTransfer(uint8_t *out, size_t len, uint8_t *in)
 {
@@ -40,6 +42,12 @@ RadioLibInterface::RadioLibInterface(LockingArduinoHal *hal, RADIOLIB_PIN_TYPE c
     : NotifiedWorkerThread("RadioIf"), module(hal, cs, irq, rst, busy), iface(_iface)
 {
     instance = this;
+
+    // Initialize unused sample slots to a sane default; sample count controls averaging.
+    for (uint8_t i = 0; i < NOISE_FLOOR_SAMPLES; i++) {
+        noiseFloorSamples[i] = NOISE_FLOOR_DEFAULT;
+    }
+
 #if defined(ARCH_STM32WL) && defined(USE_SX1262)
     module.setCb_digitalWrite(stm32wl_emulate_digitalWrite);
     module.setCb_digitalRead(stm32wl_emulate_digitalRead);
@@ -246,6 +254,87 @@ bool RadioLibInterface::findInTxQueue(NodeNum from, PacketId id)
     return txQueue.find(from, id);
 }
 
+void RadioLibInterface::updateNoiseFloor()
+{
+    // Only sample from idle receive mode. TX/RX-critical paths must return to radio work quickly.
+    if (!isReceiving || sendingPacket != NULL || isActivelyReceiving() || isIRQPending()) {
+        return;
+    }
+
+    uint32_t now = millis();
+    if (now - lastNoiseFloorUpdate < NOISE_FLOOR_UPDATE_INTERVAL_MS) {
+        return;
+    }
+    lastNoiseFloorUpdate = now;
+
+    int16_t rssi = getCurrentRSSI();
+    if (rssi == NOISE_FLOOR_INVALID || rssi >= 0 || rssi < NOISE_FLOOR_VALID_MIN) {
+        LOG_DEBUG("Skipping invalid RSSI reading: %d", rssi);
+        return;
+    }
+
+    noiseFloorSamples[currentSampleIndex] = (int32_t)rssi;
+    currentSampleIndex++;
+
+    if (currentSampleIndex >= NOISE_FLOOR_SAMPLES) {
+        currentSampleIndex = 0;
+        isNoiseFloorBufferFull = true;
+    }
+
+    currentNoiseFloor = getAverageNoiseFloorInternal();
+
+    LOG_DEBUG("Noise floor: %d dBm (samples: %d, latest: %d dBm)", currentNoiseFloor, getNoiseFloorSampleCountInternal(), rssi);
+}
+
+uint8_t RadioLibInterface::getNoiseFloorSampleCountInternal() const
+{
+    return isNoiseFloorBufferFull ? NOISE_FLOOR_SAMPLES : currentSampleIndex;
+}
+
+int32_t RadioLibInterface::getAverageNoiseFloorInternal() const
+{
+    uint8_t sampleCount = getNoiseFloorSampleCountInternal();
+
+    if (sampleCount == 0) {
+        return NOISE_FLOOR_DEFAULT;
+    }
+
+    int32_t sum = 0;
+    for (uint8_t i = 0; i < sampleCount; i++) {
+        sum += noiseFloorSamples[i];
+    }
+
+    return sum / sampleCount;
+}
+
+int32_t RadioLibInterface::getAverageNoiseFloor()
+{
+    return getAverageNoiseFloorInternal();
+}
+
+int32_t RadioLibInterface::getNoiseFloor()
+{
+    return currentNoiseFloor;
+}
+
+bool RadioLibInterface::hasNoiseFloorSamples()
+{
+    return getNoiseFloorSampleCountInternal() > 0;
+}
+
+uint8_t RadioLibInterface::getNoiseFloorSampleCount()
+{
+    return getNoiseFloorSampleCountInternal();
+}
+
+void RadioLibInterface::resetNoiseFloor()
+{
+    currentSampleIndex = 0;
+    isNoiseFloorBufferFull = false;
+    currentNoiseFloor = NOISE_FLOOR_DEFAULT;
+    LOG_INFO("Noise floor reset - rolling window collection will restart");
+}
+
 bool RadioLibInterface::randomBytes(uint8_t *buffer, size_t length)
 {
     if (!buffer || length == 0 || !iface) {
@@ -273,6 +362,7 @@ currently active.
 */
 void RadioLibInterface::onNotify(uint32_t notification)
 {
+
     switch (notification) {
     case ISR_TX:
         handleTransmitInterrupt();
@@ -404,11 +494,6 @@ bool RadioLibInterface::removePendingTXPacket(NodeNum from, PacketId id, uint32_
     return false;
 }
 
-/**
- * Remove a packet that is eligible for replacement from the TX queue
- */
-// void RadioLibInterface::removePending
-
 void RadioLibInterface::handleTransmitInterrupt()
 {
     // This can be null if we forced the device to enter standby mode.  In that case