diff --git a/.cproject b/.cproject
index 18d00a7..153daf4 100644
--- a/.cproject
+++ b/.cproject
@@ -338,7 +338,7 @@
 				</extensions>
 			</storageModule>
 			<storageModule moduleId="cdtBuildSystem" version="4.0.0">
-				<configuration artifactExtension="elf" artifactName="${ProjName}" buildArtefactType="org.eclipse.cdt.build.core.buildArtefactType.exe" buildProperties="org.eclipse.cdt.build.core.buildArtefactType=org.eclipse.cdt.build.core.buildArtefactType.exe,org.eclipse.cdt.build.core.buildType=org.eclipse.cdt.build.core.buildType.debug" cleanCommand="rm -rf" description="Release" errorParsers="org.eclipse.cdt.core.GASErrorParser;org.eclipse.cdt.core.GmakeErrorParser;org.eclipse.cdt.core.GLDErrorParser;org.eclipse.cdt.core.CWDLocator;org.eclipse.cdt.core.GCCErrorParser" id="com.st.stm32cube.ide.mcu.gnu.managedbuild.config.exe.debug.29276544.1029160395.2017222313" name="Release" parent="com.st.stm32cube.ide.mcu.gnu.managedbuild.config.exe.debug" preannouncebuildStep="Update version info within Core/Inc/git-commit-version.h" prebuildStep="cd .. &amp;&amp; bash githooks/post-checkout">
+				<configuration artifactExtension="elf" artifactName="${ProjName}" buildArtefactType="org.eclipse.cdt.build.core.buildArtefactType.exe" buildProperties="org.eclipse.cdt.build.core.buildArtefactType=org.eclipse.cdt.build.core.buildArtefactType.exe,org.eclipse.cdt.build.core.buildType=org.eclipse.cdt.build.core.buildType.debug" cleanCommand="rm -rf" description="Release" errorParsers="org.eclipse.cdt.core.GASErrorParser;org.eclipse.cdt.core.GmakeErrorParser;org.eclipse.cdt.core.GLDErrorParser;org.eclipse.cdt.core.CWDLocator;org.eclipse.cdt.core.GCCErrorParser" id="com.st.stm32cube.ide.mcu.gnu.managedbuild.config.exe.debug.29276544.1029160395.2017222313" name="Release" parent="com.st.stm32cube.ide.mcu.gnu.managedbuild.config.exe.debug" preannouncebuildStep="Update version info within Core/Inc/git-commit-version.h" prebuildStep="cd .. &amp;&amp; bash scripts/create-git-info-header.sh">
 					<folderInfo id="com.st.stm32cube.ide.mcu.gnu.managedbuild.config.exe.debug.29276544.1029160395.2017222313." name="/" resourcePath="">
 						<toolChain id="com.st.stm32cube.ide.mcu.gnu.managedbuild.toolchain.exe.debug.2038395236" name="MCU ARM GCC" superClass="com.st.stm32cube.ide.mcu.gnu.managedbuild.toolchain.exe.debug">
 							<option id="com.st.stm32cube.ide.mcu.option.internal.toolchain.type.86626326" name="Internal Toolchain Type" superClass="com.st.stm32cube.ide.mcu.option.internal.toolchain.type" useByScannerDiscovery="false" value="com.st.stm32cube.ide.mcu.gnu.managedbuild.toolchain.base.gnu-tools-for-stm32" valueType="string"/>
diff --git a/Communication/communicator.cpp b/Communication/communicator.cpp
index e35dc7a..f398d68 100644
--- a/Communication/communicator.cpp
+++ b/Communication/communicator.cpp
@@ -160,12 +160,12 @@ void communicator_runnable (void*)
 	  compass_ground_calibration.feed(output_data.m.mag);
 	  if( 0 == magnetic_ground_calibrator_countdown)
 	    {
-	      compass_calibration_t new_calibration;
+	      compass_calibration_t <int64_t, float> new_calibration;
 	      compass_ground_calibration.get_calibration_result(new_calibration.calibration);
 	      new_calibration.calibration_done = true;
 	      new_calibration.write_into_EEPROM();
 	      magnetic_calibration_done.signal();
-	      magnetic_gound_calibration = false;
+	      magnetic_gound_calibration = false; // stop this procedure
 	    }
 	}
 
@@ -251,8 +251,7 @@ void communicator_runnable (void*)
 	}
 
       organizer.report_data ( output_data);
-      if( logger_is_enabled)
-	sync_logger (); // kick logger @ 100 Hz
+      sync_logger (); // kick logger @ 100 Hz
     }
 }
 
diff --git a/Communication/sensor_dump.cpp b/Communication/sensor_dump.cpp
index d08bb12..3a0c80b 100644
--- a/Communication/sensor_dump.cpp
+++ b/Communication/sensor_dump.cpp
@@ -26,8 +26,11 @@
 #include "NMEA_format.h"
 #include "embedded_math.h"
 #include "uSD_handler.h"
+#include "pt2.h"
 
-uint64_t pabs_sum, samples, noise_energy;
+COMMON uint64_t pabs_sum, samples, noise_energy;
+COMMON pt2 <float, float> heading_decimator( 0.01);
+COMMON pt2 <float, float> inclination_decimator( 0.01);
 
 #define RAD_2_DEGREES_100 5729.6f
 
@@ -45,6 +48,8 @@ void decimate_sensor_observations( const output_data_t &output_data)
   pabs_sum += (uint64_t)(output_data.m.static_pressure);
   ++samples;
   noise_energy += SQR( (uint64_t)(output_data.m.static_pressure + 0.5f) - pabs_sum / samples);
+  heading_decimator.respond( output_data.euler.y);
+  inclination_decimator.respond( ATAN2( output_data.nav_induction_gnss.e[DOWN], output_data.nav_induction_gnss.e[NORTH]));
 }
 
 statistics get_sensor_data( void)
@@ -149,11 +154,18 @@ void format_sensor_dump( const output_data_t &output_data, string_buffer_t &NMEA
   s = integer_to_ascii_2_decimals( 100.0f * output_data.nav_induction_gnss.abs(), s);
   s=append_string( s, "\r\n");
 
-  s=append_string( s, "Mag. Inclination: ");
-  float inclination = ATAN2( output_data.nav_induction_gnss.e[DOWN], output_data.nav_induction_gnss.e[NORTH]);
-  s = integer_to_ascii_2_decimals( RAD_2_DEGREES_100 * inclination, s);
+  float heading = heading_decimator.get_output();
+  if( heading < 0.0f)
+    heading += 2.0f * M_PI_F;
+  s=append_string( s, "True Heading= ");
+  s = integer_to_ascii_2_decimals( RAD_2_DEGREES_100 * heading, s);
 
-  s=append_string( s, "\r\n");
+  s=append_string( s, " Inclination= ");
+  s = integer_to_ascii_2_decimals( RAD_2_DEGREES_100 * inclination_decimator.get_output(), s);
+
+  s=append_string( s, " MagAnomaly= ");
+  s = integer_to_ascii_2_decimals( output_data.magnetic_disturbance * 10000.0f, s);
+  s=append_string( s, " %\r\n");
 
   // here we report a fake vario value indicating the maximum magnetic field strength
   if( magnetic_gound_calibration)
diff --git a/Communication/uSD_handler.cpp b/Communication/uSD_handler.cpp
index 6c04bc9..dea12b8 100644
--- a/Communication/uSD_handler.cpp
+++ b/Communication/uSD_handler.cpp
@@ -22,7 +22,7 @@
 
  **************************************************************************/
 
- #include "system_configuration.h"
+#include "system_configuration.h"
 #include "main.h"
 #include "FreeRTOS_wrapper.h"
 #include "fatfs.h"
@@ -37,21 +37,19 @@
 #include "uSD_handler.h"
 #include "watchdog_handler.h"
 #include "EEPROM_defaults.h"
+#include "magnetic_induction_report.h"
 
 extern Semaphore setup_file_handling_completed;
 extern uint32_t UNIQUE_ID[4];
 extern bool reset_by_watchdog_requested;
 
-COMMON Queue< linear_least_square_result<float>[3] > magnetic_calibration_queue(4,"M_CALIB");
 COMMON char *crashfile;
 COMMON unsigned crashline;
-COMMON bool logger_is_enabled;
 COMMON bool magnetic_gound_calibration;
 COMMON bool dump_sensor_readings;
 
 COMMON Semaphore magnetic_calibration_done;
-
-#if RUN_DATA_LOGGER
+COMMON magnetic_induction_report_t magnetic_induction_report;
 
 FATFS fatfs;
 extern SD_HandleTypeDef hsd;
@@ -271,20 +269,21 @@ bool write_EEPROM_dump( const char * filename)
   return FR_OK;
 }
 
-void write_magnetic_calibration_file (const coordinates_t &c)
+void write_magnetic_calibration_file ( void)
 {
   FRESULT fresult;
+  FILINFO filinfo;
   FIL fp;
-  char buffer[50];
+  char buffer[100];
   char *next = buffer;
-  linear_least_square_result<float> data[3];
   int32_t writtenBytes = 0;
 
-  if (false == magnetic_calibration_queue.receive (data, 0))
-    return;
+  fresult = f_stat("magnetic", &filinfo);
+  if( (fresult != FR_OK) || ((filinfo.fattrib & AM_DIR)==0))
+    return; // directory does not exist -> do not write file
 
+  next = append_string( next, "magnetic/");
   next = format_date_time( next);
-  *next++ = (char)(data[0].id);
   append_string(next, ".mcl");
 
   fresult = f_open (&fp, buffer, FA_CREATE_ALWAYS | FA_WRITE);
@@ -294,19 +293,30 @@ void write_magnetic_calibration_file (const coordinates_t &c)
   for( unsigned i=0; i<3; ++i)
     {
       char *next = buffer;
-      next = my_ftoa (next, data[i].y_offset);
-      *next++='\t';
-      next = my_ftoa (next, data[i].slope);
-      *next++='\t';
-      next = my_ftoa (next, data[i].variance_offset);
-      *next++='\t';
-      next = my_ftoa (next, data[i].variance_slope);
-      *next++='\t';
+      next = my_ftoa (next, magnetic_induction_report.calibration[i].offset);
+      *next++=' ';
+      next = my_ftoa (next, magnetic_induction_report.calibration[i].scale);
+      *next++=' ';
+      next = my_ftoa (next, SQRT( magnetic_induction_report.calibration[i].variance));
+      *next++=' ';
       fresult = f_write (&fp, buffer, next-buffer, (UINT*) &writtenBytes);
       if( (fresult != FR_OK) || (writtenBytes != (next-buffer)))
         return;
     }
-  f_write (&fp, "\r\n", 2, (UINT*) &writtenBytes);
+
+  next = buffer;
+  float3vector induction = magnetic_induction_report.nav_induction;
+  for( unsigned i=0; i<3; ++i)
+    {
+      next = my_ftoa (next, induction[i]);
+      *next++=' ';
+    }
+
+  next = my_ftoa (next, magnetic_induction_report.nav_induction_std_deviation);
+  *next++='\r';
+  *next++='\n';
+
+  f_write (&fp, buffer, next-buffer, (UINT*) &writtenBytes);
   f_close(&fp);
 }
 
@@ -400,9 +410,15 @@ void uSD_handler_runnable (void*)
 	}
     }
 
-  fresult = f_open (&the_file, (char *)"enable.logger", FA_READ);
-  logger_is_enabled = (fresult == FR_OK);
-  f_close( &the_file); // as this is just a dummy file
+  FILINFO filinfo;
+  fresult = f_stat("logger", &filinfo);
+  if( (fresult != FR_OK) || ((filinfo.fattrib & AM_DIR)==0))
+    while( 1)
+	{
+	notify_take (true); // wait for synchronization by crash detection
+	if( crashfile)
+	  write_crash_dump();
+	}
 
   // wait until a GNSS timestamp is available.
   while (output_data.c.sat_fix_type == 0)
@@ -414,21 +430,11 @@ void uSD_handler_runnable (void*)
 
   // generate filename based on timestamp
   char out_filename[30];
-  char * next = out_filename;
+  char * next = append_string( out_filename, "logger/");
   next = format_date_time( next);
 
   write_EEPROM_dump( out_filename); // now we have date+time, start logging
 
-  if( ! logger_is_enabled) // in this case we only wait for a possible crash dump
-    {
-      while( true)
-	{
-	notify_take (true); // wait for synchronization by crash detection
-	if( crashfile)
-	  write_crash_dump();
-	}
-    }
-
   *next++ = '.';
   *next++  = 'f';
   next = format_2_digits( next, (sizeof(coordinates_t) + sizeof(measurement_data_t)) / sizeof(float));
@@ -486,9 +492,8 @@ void uSD_handler_runnable (void*)
 	{
 	  sync_counter = 0;
 	  f_sync (&the_file);
-#if LOG_MAGNETIC_CALIBRATION
-	  write_magnetic_calibration_file ( output_data.c);
-#endif
+	  if( magnetic_calibration_done.wait( 0))
+	    write_magnetic_calibration_file ();
 	}
     }
 }
@@ -578,4 +583,8 @@ extern "C" void handle_watchdog_trigger( void)
   amok_running_task_killer.resume_from_ISR();
 }
 
-#endif
+void report_magnetic_calibration_has_changed(magnetic_induction_report_t * p_magnetic_induction_report, char)
+{
+  magnetic_induction_report = *p_magnetic_induction_report;
+  magnetic_calibration_done.signal();
+}
diff --git a/Communication/uSD_handler.h b/Communication/uSD_handler.h
index 4228ab0..e8a323c 100644
--- a/Communication/uSD_handler.h
+++ b/Communication/uSD_handler.h
@@ -1,6 +1,7 @@
 #ifndef USD_HANDLER_H_
 #define USD_HANDLER_H_
 
+#include "FreeRTOS_wrapper.h"
 #include "embedded_memory.h"
 
 extern bool logger_is_enabled;
diff --git a/Core/Inc/system_configuration.h b/Core/Inc/system_configuration.h
index 4f04495..194d298 100644
--- a/Core/Inc/system_configuration.h
+++ b/Core/Inc/system_configuration.h
@@ -28,13 +28,8 @@
 #include "persistent_data.h"
 #include "git-commit-version.h"
 
-#define RUN_DATA_LOGGER			1
-
-#define PARALLEL_MAGNETIC_AHRS		0 // run second AHRS without SAT compass usage
 #define INCLUDING_NANO			1
 
-#define WRITE_MAG_CALIB_EEPROM		1
-#define LOG_MAGNETIC_CALIBRATION 	0
 #define WRITE_EEPROM_DEFAULTS		0
 #define USE_HARDWARE_EEPROM		1
 #define WITH_DENSITY_DATA		0
diff --git a/Core/Src/watchdog_handler.cpp b/Core/Src/watchdog_handler.cpp
index c2be63c..17f2a9f 100644
--- a/Core/Src/watchdog_handler.cpp
+++ b/Core/Src/watchdog_handler.cpp
@@ -25,9 +25,18 @@
 #include "system_configuration.h"
 #include "main.h"
 #include "FreeRTOS_wrapper.h"
+#include "stm32f4xx_hal.h"
+
+#define SD_DETECT_PIN         GPIO_PIN_13
+#define SD_DETECT_GPIO_PORT   GPIOC
 
 static COMMON WWDG_HandleTypeDef WwdgHandle;
 
+bool SD_is_plugged_in( void)
+{
+  return HAL_GPIO_ReadPin(SD_DETECT_GPIO_PORT, SD_DETECT_PIN) == GPIO_PIN_SET;
+}
+
 void heartbeat (void)
 {
   bool set = GPIO_PIN_SET
@@ -67,6 +76,8 @@ void watchdog_runnable (void*)
 
 #endif // ACTIVATE_WATCHDOG
 
+  bool sd_was_plugged = SD_is_plugged_in();
+
   uint8_t rythm = 0;
   for (synchronous_timer t (40); true;)
     {
@@ -83,6 +94,12 @@ void watchdog_runnable (void*)
 	watchdog_min = watchdog_actual;
 #endif
       HAL_WWDG_Refresh (&WwdgHandle);
+
+      if( (false == sd_was_plugged) && SD_is_plugged_in())
+	while( true)
+	  ; // let the watchdog reset the system
+
+      sd_was_plugged = SD_is_plugged_in();
 #endif
     }
 }
diff --git a/lib b/lib
index 233ead4..4f7a94f 160000
--- a/lib
+++ b/lib
@@ -1 +1 @@
-Subproject commit 233ead4405581adb7cc4ffbe476c9a62b104d435
+Subproject commit 4f7a94fdaac1fe49d9ba57b10cee837ab9fac012