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/LR11x0Interface.cpp

@@ -368,4 +368,10 @@ template <typename T> bool LR11x0Interface<T>::sleep()
 
     return true;
 }
+
+template <typename T> int16_t LR11x0Interface<T>::getCurrentRSSI()
+{
+    float rssi = lora.getRSSI(false, true);
+    return (int16_t)round(rssi);
+}
 #endif

src/mesh/LR11x0Interface.h

@@ -37,6 +37,8 @@ template <class T> class LR11x0Interface : public RadioLibInterface
      */
     T lora;
 
+    int16_t getCurrentRSSI() override;
+
     /**
      * Glue functions called from ISR land
      */

src/mesh/LR20x0Interface.cpp

@@ -136,17 +136,6 @@ template <typename T> bool LR20x0Interface<T>::init()
     if (res == RADIOLIB_ERR_CHIP_NOT_FOUND || res == RADIOLIB_ERR_SPI_CMD_FAILED)
         return false;
 
-        // Some basic info about the module's explicit firmware version - no other info available
-        // Currently requires radiolib godmode
-
-#if RADIOLIB_GODMODE
-    uint8_t fwMajor = 0;
-    uint8_t fwMinor = 0;
-    int versionRes = lora.getVersion(&fwMajor, &fwMinor);
-    if (versionRes == RADIOLIB_ERR_NONE)
-        LOG_DEBUG("LR20x0 FW %d.%d", fwMajor, fwMinor);
-#endif
-
     LOG_INFO("Frequency set to %f", getFreq());
     LOG_INFO("Bandwidth set to %f", bw);
     LOG_INFO("Power output set to %d", power);
@@ -154,17 +143,6 @@ template <typename T> bool LR20x0Interface<T>::init()
     if (res == RADIOLIB_ERR_NONE)
         res = lora.setCRC(2);
 
-        // Standard DCDC ramp timing from RadioLib workarounds (register 0x00F20024)
-        // Currently requires radiolib godmode
-#if RADIOLIB_GODMODE
-    if (res == RADIOLIB_ERR_NONE) {
-        uint8_t rampTimes[4] = {15, 15, 15, 15}; // Standard case for all conditions
-        res = lora.setRegMode(RADIOLIB_LR2021_REG_MODE_SIMO_NORMAL, rampTimes);
-        if (res != RADIOLIB_ERR_NONE)
-            LOG_WARN("LR2021 setRegMode failed: %d", res);
-    }
-#endif
-
 #ifdef LR2021_DIO_AS_RF_SWITCH
     bool dioAsRfSwitch = true;
 #elif defined(ARCH_PORTDUINO)
@@ -396,4 +374,10 @@ template <typename T> bool LR20x0Interface<T>::sleep()
 
     return true;
 }
+
+template <typename T> int16_t LR20x0Interface<T>::getCurrentRSSI()
+{
+    float rssi = lora.getRSSI(false, true);
+    return (int16_t)round(rssi);
+}
 #endif

src/mesh/LR20x0Interface.h

@@ -37,6 +37,8 @@ template <class T> class LR20x0Interface : public RadioLibInterface
      */
     T lora;
 
+    int16_t getCurrentRSSI() override;
+
     /**
      * Glue functions called from ISR land
      */

src/mesh/RF95Interface.cpp

@@ -341,4 +341,10 @@ bool RF95Interface::sleep()
 
     return true;
 }
+
+int16_t RF95Interface::getCurrentRSSI()
+{
+    float rssi = lora->getRSSI(false);
+    return (int16_t)round(rssi);
+}
 #endif

src/mesh/RF95Interface.h

@@ -37,6 +37,8 @@ class RF95Interface : public RadioLibInterface
      */
     virtual void disableInterrupt() override;
 
+    int16_t getCurrentRSSI() override;
+
     /**
      * Enable a particular ISR callback glue function
      */

src/mesh/RadioInterface.h

@@ -283,6 +283,12 @@ class RadioInterface
      */
     virtual void saveChannelNum(uint32_t savedChannelNum);
 
+    /**
+     * Get current RSSI reading from the radio.
+     * Returns 0 if not available.
+     */
+    virtual int16_t getCurrentRSSI() { return 0; }
+
   private:
     /**
      * Convert our modemConfig enum into wf, sf, etc...

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

src/mesh/RadioLibInterface.h

@@ -99,6 +99,26 @@ class RadioLibInterface : public RadioInterface, protected concurrency::Notified
     /// are _trying_ to receive a packet currently (note - we might just be waiting for one)
     bool isReceiving = false;
 
+  protected:
+    // Noise floor tracking - rolling window of samples.
+    static const uint8_t NOISE_FLOOR_SAMPLES = 20;
+    static const int32_t NOISE_FLOOR_DEFAULT = -120;
+    static const int32_t NOISE_FLOOR_VALID_MIN = -127;
+    static const int32_t NOISE_FLOOR_INVALID = -128;
+    int32_t noiseFloorSamples[NOISE_FLOOR_SAMPLES];
+    uint8_t currentSampleIndex = 0;
+    bool isNoiseFloorBufferFull = false;
+    uint32_t lastNoiseFloorUpdate = 0;
+    static const uint32_t NOISE_FLOOR_UPDATE_INTERVAL_MS = 5000;
+    int32_t currentNoiseFloor = NOISE_FLOOR_DEFAULT;
+
+    /**
+     * Pure virtual hook for derived radio interfaces to provide instantaneous RSSI.
+     * Implementations should return dBm, or an invalid value that updateNoiseFloor()
+     * can reject.
+     */
+    virtual int16_t getCurrentRSSI() = 0;
+
   public:
     /** Our ISR code currently needs this to find our active instance
      */
@@ -111,6 +131,17 @@ class RadioLibInterface : public RadioInterface, protected concurrency::Notified
             instance = nullptr;
     }
 
+    /**
+     * Get the current calculated noise floor in dBm
+     * Returns -120 dBm if not yet calibrated
+     */
+    int32_t getNoiseFloor();
+
+    /**
+     * Calculate the average noise floor from collected samples
+     */
+    int32_t getAverageNoiseFloor();
+
     /**
      * Glue functions called from ISR land
      */
@@ -179,6 +210,28 @@ class RadioLibInterface : public RadioInterface, protected concurrency::Notified
     /** Attempt to find a packet in the TxQueue. Returns true if the packet was found. */
     virtual bool findInTxQueue(NodeNum from, PacketId id) override;
 
+    /**
+     * Update the noise floor measurement by sampling RSSI from a slow path.
+     * This should not be called from radio interrupt or TX/RX critical paths.
+     */
+    void updateNoiseFloor();
+
+    /**
+     * Check if we have collected any noise floor samples
+     */
+    bool hasNoiseFloorSamples();
+
+    /**
+     * Get the number of samples in the rolling window
+     */
+    uint8_t getNoiseFloorSampleCount();
+
+    /**
+     * Reset the noise floor calibration
+     * Will automatically restart collection
+     */
+    void resetNoiseFloor();
+
     /**
      * Request randomness sourced from the LoRa modem, if supported by the active RadioLib interface.
      * @return true if len bytes were produced, false otherwise.
@@ -186,6 +239,9 @@ class RadioLibInterface : public RadioInterface, protected concurrency::Notified
     bool randomBytes(uint8_t *buffer, size_t length);
 
   private:
+    uint8_t getNoiseFloorSampleCountInternal() const;
+    int32_t getAverageNoiseFloorInternal() const;
+
     /** if we have something waiting to send, start a short (random) timer so we can come check for collision before actually
      * doing the transmit */
     void setTransmitDelay();

src/mesh/SX126xInterface.cpp

@@ -265,6 +265,12 @@ template <typename T> bool SX126xInterface<T>::reconfigure()
     return true;
 }
 
+template <typename T> int16_t SX126xInterface<T>::getCurrentRSSI()
+{
+    float rssi = lora.getRSSI(false);
+    return (int16_t)round(rssi);
+}
+
 template <typename T> void SX126xInterface<T>::disableInterrupt()
 {
     lora.clearDio1Action();

src/mesh/SX126xInterface.h

@@ -41,6 +41,8 @@ template <class T> class SX126xInterface : public RadioLibInterface
      */
     T lora;
 
+    int16_t getCurrentRSSI() override;
+
     /**
      * Glue functions called from ISR land
      */

src/mesh/SX128xInterface.cpp

@@ -325,4 +325,10 @@ template <typename T> bool SX128xInterface<T>::sleep()
 
     return true;
 }
+
+template <typename T> int16_t SX128xInterface<T>::getCurrentRSSI()
+{
+    float rssi = lora.getRSSI(false);
+    return (int16_t)round(rssi);
+}
 #endif

src/mesh/SX128xInterface.h

@@ -35,6 +35,8 @@ template <class T> class SX128xInterface : public RadioLibInterface
      */
     T lora;
 
+    int16_t getCurrentRSSI() override;
+
     /**
      * Glue functions called from ISR land
      */

src/modules/Telemetry/DeviceTelemetry.cpp

@@ -20,6 +20,7 @@ static constexpr uint16_t TX_HISTORY_KEY_DEVICE_TELEMETRY = 0x8001;
 
 int32_t DeviceTelemetryModule::runOnce()
 {
+
     refreshUptime();
     uint32_t lastTelemetry = transmitHistory ? transmitHistory->getLastSentToMeshMillis(TX_HISTORY_KEY_DEVICE_TELEMETRY) : 0;
     bool isImpoliteRole = isSensorOrRouterRole();
@@ -129,6 +130,8 @@ meshtastic_Telemetry DeviceTelemetryModule::getLocalStatsTelemetry()
     telemetry.variant.local_stats.num_online_nodes = numOnlineNodes;
     telemetry.variant.local_stats.num_total_nodes = nodeDB->getNumMeshNodes();
     if (RadioLibInterface::instance) {
+        RadioLibInterface::instance->updateNoiseFloor();
+        telemetry.variant.local_stats.noise_floor = RadioLibInterface::instance->getAverageNoiseFloor();
         telemetry.variant.local_stats.num_packets_tx = RadioLibInterface::instance->txGood;
         telemetry.variant.local_stats.num_packets_rx = RadioLibInterface::instance->rxGood + RadioLibInterface::instance->rxBad;
         telemetry.variant.local_stats.num_packets_rx_bad = RadioLibInterface::instance->rxBad;
@@ -137,6 +140,8 @@ meshtastic_Telemetry DeviceTelemetryModule::getLocalStatsTelemetry()
     }
 #ifdef ARCH_PORTDUINO
     if (SimRadio::instance) {
+        if (!RadioLibInterface::instance)
+            telemetry.variant.local_stats.noise_floor = SimRadio::instance->getCurrentRSSI();
         telemetry.variant.local_stats.num_packets_tx = SimRadio::instance->txGood;
         telemetry.variant.local_stats.num_packets_rx = SimRadio::instance->rxGood + SimRadio::instance->rxBad;
         telemetry.variant.local_stats.num_packets_rx_bad = SimRadio::instance->rxBad;
@@ -152,10 +157,11 @@ meshtastic_Telemetry DeviceTelemetryModule::getLocalStatsTelemetry()
         telemetry.variant.local_stats.num_tx_relay_canceled = router->txRelayCanceled;
     }
 
-    LOG_INFO("Sending local stats: uptime=%i, channel_utilization=%f, air_util_tx=%f, num_online_nodes=%i, num_total_nodes=%i",
+    LOG_INFO("Sending local stats: uptime=%i, channel_utilization=%f, air_util_tx=%f, num_online_nodes=%i, num_total_nodes=%i, "
+             "noise_floor=%d",
              telemetry.variant.local_stats.uptime_seconds, telemetry.variant.local_stats.channel_utilization,
              telemetry.variant.local_stats.air_util_tx, telemetry.variant.local_stats.num_online_nodes,
-             telemetry.variant.local_stats.num_total_nodes);
+             telemetry.variant.local_stats.num_total_nodes, telemetry.variant.local_stats.noise_floor);
 
     LOG_INFO("num_packets_tx=%i, num_packets_rx=%i, num_packets_rx_bad=%i", telemetry.variant.local_stats.num_packets_tx,
              telemetry.variant.local_stats.num_packets_rx, telemetry.variant.local_stats.num_packets_rx_bad);
@@ -198,4 +204,4 @@ bool DeviceTelemetryModule::sendTelemetry(NodeNum dest, bool phoneOnly)
         service->sendToMesh(p, RX_SRC_LOCAL, true);
     }
     return true;
-}
+}

src/platform/portduino/SimRadio.cpp

@@ -362,4 +362,10 @@ uint32_t SimRadio::getPacketTime(uint32_t pl, bool received)
 
     uint32_t msecs = tPacket * 1000;
     return msecs;
+}
+
+int16_t SimRadio::getCurrentRSSI()
+{
+    // Simulated radio - return a reasonable default noise floor
+    return -120;
 }

src/platform/portduino/SimRadio.h

@@ -48,6 +48,8 @@ class SimRadio : public RadioInterface, protected concurrency::NotifiedWorkerThr
     // Convert Compressed_msg to normal msg and receive it
     void unpackAndReceive(meshtastic_MeshPacket &p);
 
+    int16_t getCurrentRSSI() override;
+
     /**
      * Debugging counts
      */
@@ -93,4 +95,4 @@ class SimRadio : public RadioInterface, protected concurrency::NotifiedWorkerThr
     virtual uint32_t getPacketTime(uint32_t pl, bool received = false) override;
 };
 
-extern SimRadio *simRadio;
+extern SimRadio *simRadio;

variants/nrf52840/diy/nrf52_promicro_diy_tcxo/platformio.ini

@@ -15,7 +15,6 @@ board = promicro-nrf52840
 build_flags = ${nrf52840_base.build_flags}
   -I variants/nrf52840/diy/nrf52_promicro_diy_tcxo
   -D NRF52_PROMICRO_DIY
-  ; -D RADIOLIB_GODMODE=1 ; needed for some LR2021 items, but not enabled by default.
 build_src_filter = ${nrf52_base.build_src_filter} +<../variants/nrf52840/diy/nrf52_promicro_diy_tcxo>
 debug_tool = jlink