diff --git a/src/NoiseFloorDetector.cpp b/src/NoiseFloorDetector.cpp
index 3abc32f..7fa5a60 100644
--- a/src/NoiseFloorDetector.cpp
+++ b/src/NoiseFloorDetector.cpp
@@ -22,14 +22,15 @@ NoiseFloorDetector &NoiseFloorDetector::instance()
 NoiseFloorDetector::NoiseFloorDetector()
     : mUTC(0), mStartTime(0), mLastDumpTime(0)
 {
+    mSorted.reserve(WINDOW_SIZE);
     EventQueue::instance().addObserver(this, CLOCK_EVENT);
 }
 
-uint8_t NoiseFloorDetector::report(VHFChannel channel, uint8_t rssi)
+void NoiseFloorDetector::report(VHFChannel channel, uint8_t rssi)
 {
     // If we don't have time yet, we certainly don't have fix so we can't be transmitting anyway, so no data collection
     if ( mUTC == 0 )
-        return 0xff;
+        return;
 
     if ( mData.find(channel) == mData.end() ) {
         ChannelReadings r;
@@ -38,7 +39,7 @@ uint8_t NoiseFloorDetector::report(VHFChannel channel, uint8_t rssi)
     }
 
     ChannelReadings &window = mData[channel];
-    return processSample(window, rssi);
+    processSample(window, rssi);
 }
 
 uint8_t NoiseFloorDetector::getNoiseFloor(VHFChannel channel)
@@ -69,7 +70,7 @@ void NoiseFloorDetector::processEvent(Event *e)
     }
 }
 
-uint8_t NoiseFloorDetector::processSample(ChannelReadings &window, uint8_t rssi)
+void NoiseFloorDetector::processSample(ChannelReadings &window, uint8_t rssi)
 {
     while ( window.size() >= WINDOW_SIZE )
         window.pop_back();
@@ -79,7 +80,7 @@ uint8_t NoiseFloorDetector::processSample(ChannelReadings &window, uint8_t rssi)
         r.timestamp = mUTC;
         r.reading = rssi;
         window.push_back(r);
-        return 0xff;
+        return;
     }
 
     // Insert the reading at the start if it qualifies
@@ -92,11 +93,6 @@ uint8_t NoiseFloorDetector::processSample(ChannelReadings &window, uint8_t rssi)
             break;
         }
     }
-
-    if ( mUTC - mStartTime < 30 )
-        return 0xff;
-
-    return medianValue(window);
 }
 
 uint8_t NoiseFloorDetector::medianValue(ChannelReadings &window)
@@ -104,13 +100,12 @@ uint8_t NoiseFloorDetector::medianValue(ChannelReadings &window)
     if ( window.empty() )
         return 0xff;
 
-    vector<uint8_t> sorted;
-    sorted.reserve(WINDOW_SIZE);
+    mSorted.clear();
     for ( ChannelReadings::iterator i = window.begin(); i != window.end(); ++i )
-        sorted.push_back(i->reading);
+        mSorted.push_back(i->reading);
 
-    sort(sorted.begin(), sorted.end());
-    return sorted[sorted.size()/2];
+    sort(mSorted.begin(), mSorted.end());
+    return mSorted[mSorted.size()/2];
 }
 
 
diff --git a/src/NoiseFloorDetector.hpp b/src/NoiseFloorDetector.hpp
index 2dd5535..6520772 100644
--- a/src/NoiseFloorDetector.hpp
+++ b/src/NoiseFloorDetector.hpp
@@ -21,7 +21,7 @@ public:
 
 
     // Called directly by each receiver to report every RSSI reading at every SOTDMA slot, returns latest noise floor or 0xff if not enough data exists
-    uint8_t report(VHFChannel channel, uint8_t rssi);
+    void report(VHFChannel channel, uint8_t rssi);
 
     void reset();
 
@@ -40,7 +40,7 @@ private:
 
 private:
     NoiseFloorDetector();
-    uint8_t processSample(ChannelReadings &window, uint8_t rssi);
+    void processSample(ChannelReadings &window, uint8_t rssi);
     uint8_t medianValue(ChannelReadings &window);
     void dump();
 private:
@@ -48,6 +48,8 @@ private:
     time_t          mStartTime;
     time_t          mLastDumpTime;
     ChannelData     mData;
+    vector<uint8_t> mSorted;
 };
 
+
 #endif /* NOISEFLOORDETECTOR_HPP_ */
diff --git a/src/globals.h b/src/globals.h
index 235a259..0759eca 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -17,8 +17,8 @@
 
 
 /*
- * If this is defined, the device transmits low-power carrier at a nominal frequency of 162.075Mhz,
- * two channels above AIS. This is meant to be used for crystal calibration only
+ * If this is defined, the device transmits low-power carrier on channel 86 (161.925MHz).
+ * This is meant to be used for crystal calibration only
  */
 //#define CALIBRATION_MODE               1
 
@@ -36,7 +36,7 @@
 #ifdef TX_TEST_MODE
 #define TX_POWER_LEVEL              PWR_P16
 #else
-#define TX_POWER_LEVEL              PWR_M10
+#define TX_POWER_LEVEL              PWR_M27
 #endif
 #endif
 
@@ -44,7 +44,7 @@
 #define OUTPUT_GPS_NMEA
 #define ENABLE_PRINTF2
 
-// Some AIS messages can occupy 5 time slots (5x256 = 1280). We call it quits at 2 slots.
+// Some AIS messages can occupy 5 time slots (5x256 = 1280). Nothing we care about exceeds 2 slots.
 #define MAX_AIS_RX_PACKET_SIZE      512
 
 
@@ -54,7 +54,7 @@
 // For testing, it's necessary to transmit longer packets for a basic RTL-SDR receiver to not "miss" them.
 #define MAX_AIS_TX_PACKET_SIZE      1280
 #else
-// As a class B transponder, we never transmit anything bigger than 256 bits
+// As a class B transponder, we never transmit anything bigger than 240 bits.
 #define MAX_AIS_TX_PACKET_SIZE       300
 #endif
 
diff --git a/src/main.cpp b/src/main.cpp
index f647de1..27b7c03 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -15,8 +15,9 @@
 #include "TXScheduler.hpp"
 #include "Utils.hpp"
 #include "system_stm32f30x.h"
+#include "core_cm4.h"
 #include "stm32f30x.h"
-
+#include <diag/Trace.h>
 #include "DataTerminal.hpp"
 #include "TXScheduler.hpp"
 #include "DebugPrinter.hpp"
@@ -57,6 +58,13 @@ main(int argc, char* argv[])
     // at high speed.
     printf2_Init(230400);
 
+#ifdef DEBUG
+    // Disable buffered memory writes to debug imprecise bus faults
+    SCnSCB->ACTLR |= SCnSCB_ACTLR_DISDEFWBUF_Msk;
+    trace_printf("ACTLR: %.8x\n", SCnSCB->ACTLR);
+#endif
+
+
     EEPROM::instance().init();
     /*
     struct StationData __d;