diff --git a/Controller.cpp b/Controller.cpp
index c765807..5b6f52d 100644
--- a/Controller.cpp
+++ b/Controller.cpp
@@ -16,6 +16,7 @@
 #include <Indoor/floorplan/v2/FloorplanHelper.h>
 
 #include <Indoor/sensors/radio/WiFiGridEstimator.h>
+#include <Indoor/sensors/radio/setup/WiFiOptimizerLogDistCeiling.h>
 
 #include <Indoor/Assertions.h>
 
@@ -28,11 +29,13 @@
 #include "sensors/dummy/SensorFactoryDummy.h"
 #include "sensors/android/SensorFactoryAndroid.h"
 #include "sensors/offline/SensorFactoryOffline.h"
+#include "sensors/SensorWriter.h"
 
 #include "tools/calibration/WiFiCalibrationDataModel.h"
 
 #include "nav/NavController.h"
 
+
 Controller::Controller() {
 
 	// OpenGL setup
@@ -51,13 +54,29 @@ Controller::Controller() {
 
 	//SensorFactory::set(new SensorFactoryOffline(Settings::Data::getOfflineDir() + "bergwerk/path3/nexus/vor/1454782562231.csv"));
 	//SensorFactory::set(new SensorFactoryOffline(Settings::Data::getOfflineDir() + "/bergwerk/path4/nexus/rueck/1454776724285_rueck.csv"));
-	SensorFactory::set(new SensorFactoryOffline(Settings::Data::getOfflineDir() + "/bergwerk/path4/nexus/vor/1454776525797.csv"));
+	//SensorFactory::set(new SensorFactoryOffline(Settings::Data::getOfflineDir() + "/bergwerk/path4/nexus/vor/1454776525797.csv"));
+
+	// live data on the smartphone
+	if (1 == 1) {
+
+		// use android's sensors
+		SensorFactory::set(new SensorFactoryAndroid());
+
+		// write them to file??
+		//const std::string file = Settings::Data::getRecordsDir() + "/" + std::to_string(Timestamp::fromUnixTime().ms()) + ".csv";
+		//SensorWriter* writer = new SensorWriter();
+		//writer->start(file);
+
+		// start the sensors
+		SensorFactory::get().getAccelerometer().start();
+		SensorFactory::get().getGyroscope().start();
+		SensorFactory::get().getBarometer().start();
+		SensorFactory::get().getWiFi().start();
+		SensorFactory::get().getGPS().start();
+		SensorFactory::get().getCompass().start();
+
+	}
 
-//	SensorFactory::set(new SensorFactoryAndroid());
-//	SensorFactory::get().getAccelerometer().start();
-//	SensorFactory::get().getGyroscope().start();
-//	SensorFactory::get().getBarometer().start();
-//	SensorFactory::get().getWiFi().start();
 
 
 	// create the main window
@@ -126,13 +145,13 @@ void buildGridOnce(Grid<MyGridNode>* grid, Floorplan::IndoorMap* map, const std:
 
 		WiFiCalibrationDataModel mdl(fpFile);
 		Assert::isFalse(mdl.getFingerprints().empty(), "no fingerprints available!");
-		WiFiOptimizer opt(map, Settings::WiFiModel::vg_calib);
+		WiFiOptimizer::LogDistCeiling opt(map, Settings::WiFiModel::vg_calib);
 		for (const WiFiFingerprint& fp : mdl.getFingerprints()) {
 			opt.addFingerprint(fp);
 		}
-		const std::vector<WiFiOptimizer::APParamsMAC> res = opt.optimizeAll();
+		const WiFiOptimizer::LogDistCeiling::APParamsList res = opt.optimizeAll(opt.NONE);
 		WiFiGridEstimator::estimate(*grid, wifiModel, Settings::smartphoneAboveGround);
-		for (const WiFiOptimizer::APParamsMAC& ap : res) {
+		for (const WiFiOptimizer::LogDistCeiling::APParamsMAC& ap : res.get()) {
 			const WiFiModelLogDistCeiling::APEntry entry(ap.params.getPos(), ap.params.txp, ap.params.exp, ap.params.waf);
 			wifiModel.addAP(ap.mac, entry);
 		}
diff --git a/Settings.h b/Settings.h
index 1319c91..304a916 100644
--- a/Settings.h
+++ b/Settings.h
@@ -80,11 +80,11 @@ namespace Settings {
 			//		qDebug(folder.c_str());
 			//		return folder;
 					//return "/storage/sdcard1/YASMIN/";
-				std::string f1 = "/storage/sdcard1/YASMIN/";
-				std::string f2 = "/sdcard/YASMIN/";
+				const std::string f1 = "/storage/sdcard1/YASMIN/";
+				const std::string f2 = "/sdcard/YASMIN/";
 				if (QFile(f1.c_str()).exists()) {return f1;}
 				if (QFile(f2.c_str()).exists()) {return f2;}
-				throw Exception("data folder missing");
+				throw Exception("data folder missing. one of those:\n" + f1 + "\n" + f2);
 			#else
 				//return "/home/toni/Documents/programme/localization/YASMIN/YASMIN_DATA/";
 				return "/apps/android/workspace/YASMIN_DATA/";
@@ -100,6 +100,10 @@ namespace Settings {
 			return getRoot() + "offline/";
 		}
 
+		static inline std::string getRecordsDir() {
+			return getRoot() + "records/";
+		}
+
 	}
 
 }
diff --git a/ipin/StepLoggerWrapperAndroid.h b/ipin/StepLoggerWrapperAndroid.h
index 0c6560c..7a342fb 100644
--- a/ipin/StepLoggerWrapperAndroid.h
+++ b/ipin/StepLoggerWrapperAndroid.h
@@ -48,7 +48,7 @@ private:
 	/** call java */
 	void log(const double x, const double y, const double z) {
 
-#ifdef ANDROID
+#ifdef _ANDROID
 		//Log::add("SLWA", "calling android with lon/lat/floor");
 
         double rounded_z = std::round(z);
diff --git a/sensors/CompassSensor.h b/sensors/CompassSensor.h
new file mode 100644
index 0000000..c1dc35c
--- /dev/null
+++ b/sensors/CompassSensor.h
@@ -0,0 +1,12 @@
+#ifndef COMPASSSENSOR_H
+#define COMPASSSENSOR_H
+
+#include "Sensor.h"
+#include <Indoor/sensors/imu/CompassData.h>
+
+class CompassSensor : public Sensor<CompassData> {
+
+};
+
+
+#endif // COMPASSSENSOR_H
diff --git a/sensors/GPSSensor.h b/sensors/GPSSensor.h
new file mode 100644
index 0000000..c62d92a
--- /dev/null
+++ b/sensors/GPSSensor.h
@@ -0,0 +1,11 @@
+#ifndef GPSSENSOR_H
+#define GPSSENSOR_H
+
+#include "Sensor.h"
+#include <Indoor/sensors/gps/GPSData.h>
+
+class GPSSensor : public Sensor<GPSData> {
+
+};
+
+#endif // GPSSENSOR_H
diff --git a/sensors/SensorFactory.h b/sensors/SensorFactory.h
index d7acbd1..4bdcb18 100644
--- a/sensors/SensorFactory.h
+++ b/sensors/SensorFactory.h
@@ -20,6 +20,14 @@
 #include "android/BarometerSensorAndroid.h"
 #include "dummy/BarometerSensorDummy.h"
 
+#include "GPSSensor.h"
+#include "android/GPSSensorAndroid.h"
+#include "dummy/GPSSensorDummy.h"
+
+#include "CompassSensor.h"
+#include "android/CompassSensorAndroid.h"
+#include "dummy/CompassSensorDummy.h"
+
 #include "StepSensor.h"
 #include "TurnSensor.h"
 #include "ActivitySensor.h"
@@ -39,13 +47,13 @@ public:
 
 	/** set the to-be-used sensor-fatory */
 	static void set(SensorFactory* fac) {
-		Assert::isNull(*getPtr(), "set() was already called. currentely this is not intended");
+		Assert::isNull(*getPtr(), "SensorFactory::set() was already called. currentely this is not intended");
 		*getPtr() = fac;
 	}
 
 	/** get the currently configured sensory factory */
 	static SensorFactory& get() {
-		Assert::isNotNull(*getPtr(), "call set() first to set an actual factory instance!");
+		Assert::isNotNull(*getPtr(), "call SensorFactory::set() first to set an actual factory instance!");
 		return **getPtr();
 	}
 
@@ -63,6 +71,13 @@ public:
 	/** get the Barometer sensor */
 	virtual BarometerSensor& getBarometer() = 0;
 
+	/** get the compass sensor */
+	virtual CompassSensor& getCompass() = 0;
+
+	/** get the gps sensor */
+	virtual GPSSensor& getGPS() = 0;
+
+
 	/** get the Step sensor */
 	StepSensor& getSteps() {
 		static StepSensor steps(getAccelerometer());
diff --git a/sensors/SensorWriter.h b/sensors/SensorWriter.h
new file mode 100644
index 0000000..9a686ec
--- /dev/null
+++ b/sensors/SensorWriter.h
@@ -0,0 +1,101 @@
+#ifndef SENSORWRITER_H
+#define SENSORWRITER_H
+
+#include "AccelerometerSensor.h"
+#include "GyroscopeSensor.h"
+#include "BarometerSensor.h"
+#include "StepSensor.h"
+#include "TurnSensor.h"
+#include "WiFiSensor.h"
+#include "ActivitySensor.h"
+#include "GPSSensor.h"
+#include "CompassSensor.h"
+#include "SensorFactory.h"
+
+#include <Indoor/sensors/offline/FileWriter.h>
+
+/**
+ * receives live sensor data
+ * writes it to a file
+ */
+class SensorWriter :
+		public SensorListener<AccelerometerData>,
+		public SensorListener<GyroscopeData>,
+		public SensorListener<BarometerData>,
+//		public SensorListener<ActivityData>,
+//		public SensorListener<StepData>,
+//		public SensorListener<TurnData>,
+		public SensorListener<WiFiMeasurements>,
+		public SensorListener<GPSData>,
+		public SensorListener<CompassData> {
+
+private:
+
+	Offline::FileWriter writer;
+	bool active = false;
+
+public:
+
+	/** empty ctor */
+	SensorWriter() {
+
+		// attach as listener to all sensors we want to store
+		SensorFactory::get().getAccelerometer().addListener(this);
+		SensorFactory::get().getGyroscope().addListener(this);
+		SensorFactory::get().getBarometer().addListener(this);
+//		SensorFactory::get().getActivity().addListener(this);
+//		SensorFactory::get().getSteps().addListener(this);
+//		SensorFactory::get().getTurns().addListener(this);
+		SensorFactory::get().getWiFi().addListener(this);
+		SensorFactory::get().getCompass().addListener(this);
+		SensorFactory::get().getGPS().addListener(this);
+
+	}
+
+
+
+	void start(const std::string& file) {
+		writer.open(file);
+		active = true;
+	}
+
+	void stop() {
+		active = false;
+		writer.close();
+	}
+
+public:
+
+	virtual void onSensorData(Sensor<AccelerometerData>* , const Timestamp ts, const AccelerometerData& data) override {
+		if (!active) {return;}
+		writer.add(ts, data);
+	}
+
+	virtual void onSensorData(Sensor<GyroscopeData>* , const Timestamp ts, const GyroscopeData& data) override {
+		if (!active) {return;}
+		writer.add(ts, data);
+	}
+
+	virtual void onSensorData(Sensor<BarometerData>* , const Timestamp ts, const BarometerData& data) override {
+		if (!active) {return;}
+		writer.add(ts, data);
+	}
+
+	virtual void onSensorData(Sensor<WiFiMeasurements>* , const Timestamp ts, const WiFiMeasurements& data) override {
+		if (!active) {return;}
+		writer.add(ts, data);
+	}
+
+	virtual void onSensorData(Sensor<GPSData>* , const Timestamp ts, const GPSData& data) override {
+		if (!active) {return;}
+		writer.add(ts, data);
+	}
+
+	virtual void onSensorData(Sensor<CompassData>* , const Timestamp ts, const CompassData& data) override {
+		if (!active) {return;}
+		writer.add(ts, data);
+	}
+
+};
+
+#endif // SENSORWRITER_H
diff --git a/sensors/android/AccelerometerSensorAndroid.h b/sensors/android/AccelerometerSensorAndroid.h
index 210b647..1632856 100644
--- a/sensors/android/AccelerometerSensorAndroid.h
+++ b/sensors/android/AccelerometerSensorAndroid.h
@@ -1,7 +1,6 @@
 #ifndef ACCELEROMETERSENSORANDROID_H
 #define ACCELEROMETERSENSORANDROID_H
 
-
 #ifdef ANDROID
 
 #include <sstream>
diff --git a/sensors/android/CompassSensorAndroid.h b/sensors/android/CompassSensorAndroid.h
new file mode 100644
index 0000000..a9a9c31
--- /dev/null
+++ b/sensors/android/CompassSensorAndroid.h
@@ -0,0 +1,63 @@
+#ifndef COMPASSSENSORANDROID_H
+#define COMPASSSENSORANDROID_H
+
+#ifdef ANDROID
+
+#include <sstream>
+
+#include "../CompassSensor.h"
+
+#include <QtSensors/QCompass>
+
+class CompassSensorAndroid : public CompassSensor {
+
+private:
+
+	QCompass compass;
+
+	/** hidden ctor. use singleton */
+	CompassSensorAndroid() {
+		;
+	}
+
+	bool started = false;
+
+public:
+
+	/** singleton access */
+	static CompassSensorAndroid& get() {
+		static CompassSensorAndroid compass;
+		return compass;
+	}
+
+	void start() override {
+
+		if (started) {return;}
+		started = true;
+
+		auto onSensorData = [&] () {
+			CompassData data(
+				compass.reading()->azimuth(),
+				compass.reading()->calibrationLevel()
+			);
+			informListeners(data);
+		};
+
+		compass.connect(&compass, &QCompass::readingChanged, onSensorData);
+		compass.start();
+
+	}
+
+	bool isRunning() const override {
+		return started;
+	}
+
+	void stop() override {
+		throw "TODO";
+	}
+
+};
+
+#endif
+
+#endif // COMPASSSENSORANDROID_H
diff --git a/sensors/android/GPSSensorAndroid.h b/sensors/android/GPSSensorAndroid.h
new file mode 100644
index 0000000..b5629ed
--- /dev/null
+++ b/sensors/android/GPSSensorAndroid.h
@@ -0,0 +1,74 @@
+#ifndef GPSSENSORANDROID_H
+#define GPSSENSORANDROID_H
+
+#ifdef ANDROID
+
+#include <sstream>
+
+#include "../GPSSensor.h"
+
+#include <QtPositioning>
+
+class GPSSensorAndroid : public GPSSensor {
+
+private:
+
+	QGeoPositionInfoSource* source;
+
+	/** hidden ctor. use singleton */
+	GPSSensorAndroid() {
+
+		source = QGeoPositionInfoSource::createDefaultSource(nullptr);
+		return;
+
+	}
+
+	bool started = false;
+
+public:
+
+	/** singleton access */
+	static GPSSensorAndroid& get() {
+		static GPSSensorAndroid gps;
+		return gps;
+	}
+
+	void start() override {
+
+		if (started) {return;}
+		started = true;
+
+		auto onPositionData = [&] (const QGeoPositionInfo& update) {
+
+			GPSData data(
+				//Timestamp::ms(update.timestamp().toMSecsSinceEpoch()),
+				Timestamp::fromRunningTime(),
+				update.coordinate().latitude(),
+				update.coordinate().longitude(),
+				update.coordinate().altitude()
+			);
+
+			informListeners(data);
+
+		};
+
+		if (source) {
+			source->connect(source, &QGeoPositionInfoSource::positionUpdated, onPositionData);
+			source->startUpdates();
+		}
+
+	}
+
+	bool isRunning() const override {
+		return started;
+	}
+
+	void stop() override {
+		throw "TODO";
+	}
+
+};
+
+#endif // ANDROID
+
+#endif // GPSSENSORANDROID_H
diff --git a/sensors/android/SensorFactoryAndroid.h b/sensors/android/SensorFactoryAndroid.h
index 454e71a..8729c02 100644
--- a/sensors/android/SensorFactoryAndroid.h
+++ b/sensors/android/SensorFactoryAndroid.h
@@ -9,6 +9,8 @@
 #include "AccelerometerSensorAndroid.h"
 #include "GyroscopeSensorAndroid.h"
 #include "BarometerSensorAndroid.h"
+#include "CompassSensorAndroid.h"
+#include "GPSSensorAndroid.h"
 
 /**
  * sensor factory that provides real hardware sensors from
@@ -34,6 +36,14 @@ public:
 		return BarometerSensorAndroid::get();
 	}
 
+	CompassSensor& getCompass() override {
+		return CompassSensorAndroid::get();
+	}
+
+	GPSSensor& getGPS() override {
+		return GPSSensorAndroid::get();
+	}
+
 };
 
 #endif
diff --git a/sensors/dummy/CompassSensorDummy.h b/sensors/dummy/CompassSensorDummy.h
new file mode 100644
index 0000000..eaf77b6
--- /dev/null
+++ b/sensors/dummy/CompassSensorDummy.h
@@ -0,0 +1,43 @@
+#ifndef COMPASSSENSORDUMMY_H
+#define COMPASSSENSORDUMMY_H
+
+#include "../CompassSensor.h"
+#include "RandomSensor.h"
+#include <random>
+
+class CompassSensorDummy : public RandomSensor<CompassData, CompassSensor> {
+
+private:
+
+	std::thread thread;
+
+	/** hidden ctor */
+	CompassSensorDummy() : RandomSensor(Timestamp::fromMS(100)) {
+		;
+	}
+
+public:
+
+	/** singleton access */
+	static CompassSensorDummy& get() {
+		static CompassSensorDummy compass;
+		return compass;
+	}
+
+protected:
+
+	std::minstd_rand gen;
+	std::uniform_real_distribution<float> distNoise = std::uniform_real_distribution<float>(-0.07, +0.07);
+
+	CompassData getRandomEntry() override {
+
+		const Timestamp ts = Timestamp::fromRunningTime();
+
+		const float azimuth = 0 + std::sin(ts.sec()) * 0.5 + distNoise(gen);
+		return CompassData(azimuth);
+
+	}
+
+};
+
+#endif // COMPASSSENSORDUMMY_H
diff --git a/sensors/dummy/GPSSensorDummy.h b/sensors/dummy/GPSSensorDummy.h
new file mode 100644
index 0000000..5d8ae83
--- /dev/null
+++ b/sensors/dummy/GPSSensorDummy.h
@@ -0,0 +1,46 @@
+#ifndef GPSSENSORDUMMY_H
+#define GPSSENSORDUMMY_H
+
+
+#include "../GPSSensor.h"
+#include "RandomSensor.h"
+#include <random>
+
+class GPSSensorDummy : public RandomSensor<GPSData, GPSSensor> {
+
+private:
+
+	std::thread thread;
+
+	/** hidden ctor */
+	GPSSensorDummy() : RandomSensor(Timestamp::fromMS(1000)) {
+		;
+	}
+
+public:
+
+	/** singleton access */
+	static GPSSensorDummy& get() {
+		static GPSSensorDummy gps;
+		return gps;
+	}
+
+protected:
+
+	std::minstd_rand gen;
+	std::uniform_real_distribution<float> distNoise = std::uniform_real_distribution<float>(-0.09, +0.09);
+
+	GPSData getRandomEntry() override {
+
+		const Timestamp ts = Timestamp::fromRunningTime();
+		const float lat = 49.7773992;
+		const float lon = 9.9627029;
+		const float alt = 100;
+		return GPSData(ts, lat, lon, alt);
+
+	}
+
+};
+
+
+#endif // GPSSENSORDUMMY_H
diff --git a/sensors/dummy/SensorFactoryDummy.h b/sensors/dummy/SensorFactoryDummy.h
index 2af30f1..3d4911c 100644
--- a/sensors/dummy/SensorFactoryDummy.h
+++ b/sensors/dummy/SensorFactoryDummy.h
@@ -7,6 +7,8 @@
 #include "AccelerometerSensorDummy.h"
 #include "GyroscopeSensorDummy.h"
 #include "BarometerSensorDummy.h"
+#include "GPSSensorDummy.h"
+#include "CompassSensorDummy.h"
 
 /**
  * sensor factory that provides sensors that fire dummy data
@@ -31,6 +33,14 @@ public:
 		return BarometerSensorDummy::get();
 	}
 
+	CompassSensor& getCompass() override {
+		return CompassSensorDummy::get();
+	}
+
+	GPSSensor& getGPS() override {
+		return GPSSensorDummy::get();
+	}
+
 };
 
 #endif // SENSORFACTORYDUMMY_H
diff --git a/sensors/offline/AllInOneSensor.h b/sensors/offline/AllInOneSensor.h
index 21001f8..956a993 100644
--- a/sensors/offline/AllInOneSensor.h
+++ b/sensors/offline/AllInOneSensor.h
@@ -7,11 +7,16 @@
 #include "../AccelerometerSensor.h"
 #include "../GyroscopeSensor.h"
 #include "../BarometerSensor.h"
+#include "../CompassSensor.h"
+#include "../GPSSensor.h"
+
 #include <Indoor/sensors/offline/OfflineAndroid.h>
+#include <Indoor/sensors/offline/Listener.h>
 
 class AllInOneSensor :
 		public WiFiSensor, public AccelerometerSensor, public GyroscopeSensor, public BarometerSensor,
-		public OfflineAndroidListener {
+		public CompassSensor, public GPSSensor,
+		public Offline::Listener {
 
 private:
 
@@ -74,6 +79,18 @@ protected:
 		BarometerSensor::informListeners(ts, data);
 	}
 
+	virtual void onGPS(const Timestamp _ts, const GPSData data) override {
+		const Timestamp ts = relativeTS(_ts);
+		handbrake(ts);
+		GPSSensor::informListeners(ts, data);
+	}
+
+	virtual void onCompass(const Timestamp _ts, const CompassData data) override {
+		const Timestamp ts = relativeTS(_ts);
+		handbrake(ts);
+		CompassSensor::informListeners(ts, data);
+	}
+
 private:
 
 	Timestamp baseTS;
diff --git a/sensors/offline/SensorFactoryOffline.h b/sensors/offline/SensorFactoryOffline.h
index bbde418..8bba373 100644
--- a/sensors/offline/SensorFactoryOffline.h
+++ b/sensors/offline/SensorFactoryOffline.h
@@ -38,6 +38,14 @@ public:
 		return allInOne;
 	}
 
+	CompassSensor& getCompass() override {
+		return allInOne;
+	}
+
+	GPSSensor& getGPS() override {
+		return allInOne;
+	}
+
 };
 
 #endif // SENSORFACTORYOFFLINE_H
diff --git a/ui/debug/PlotGPS.cpp b/ui/debug/PlotGPS.cpp
new file mode 100644
index 0000000..49c1c57
--- /dev/null
+++ b/ui/debug/PlotGPS.cpp
@@ -0,0 +1,37 @@
+#include "PlotGPS.h"
+#include <QPainter>
+
+PlotGPS::PlotGPS(QWidget *parent) : QWidget(parent) {
+
+	setMinimumWidth(32);
+	setMinimumHeight(96);
+
+}
+
+void PlotGPS::add(const Timestamp ts, const GPSData& data) {
+	(void) ts;
+	this->gpsData = data;
+}
+
+void PlotGPS::paintEvent(QPaintEvent* evt) {
+
+	(void) evt;
+	QPainter p(this);
+
+	// frame
+	p.fillRect(0,0,width(),height(),QColor(255,255,255,192));
+	p.setPen(Qt::black);
+	p.drawRect(0,0,width()-1,height()-1);
+
+	// turn [relative]
+	const QPen pen(Qt::black);
+	p.setPen(pen);
+	p.drawText(4, 1*12, QString::number(gpsData.tsReceived.ms()));
+	p.drawText(4, 2*12, QString::number(gpsData.lat));
+	p.drawText(4, 3*12, QString::number(gpsData.lon));
+	p.drawText(4, 4*12, QString::number(gpsData.alt));
+	p.drawText(4, 5*12, QString::number(gpsData.accuracy));
+
+	p.end();
+
+}
diff --git a/ui/debug/PlotGPS.h b/ui/debug/PlotGPS.h
new file mode 100644
index 0000000..cdafffb
--- /dev/null
+++ b/ui/debug/PlotGPS.h
@@ -0,0 +1,32 @@
+#ifndef PLOTGPS_H
+#define PLOTGPS_H
+
+
+#include <QWidget>
+#include "../sensors/GPSSensor.h"
+
+#include <Indoor/data/Timestamp.h>
+
+class PlotGPS : public QWidget {
+
+	Q_OBJECT
+
+private:
+
+	GPSData gpsData;
+
+public:
+
+	explicit PlotGPS(QWidget *parent = 0);
+
+	void add(const Timestamp ts, const GPSData& data);
+
+signals:
+
+public slots:
+
+	void paintEvent(QPaintEvent*);
+
+};
+
+#endif // PLOTGPS_H
diff --git a/ui/debug/PlotTurns.cpp b/ui/debug/PlotTurns.cpp
index 3b94e59..d3966af 100644
--- a/ui/debug/PlotTurns.cpp
+++ b/ui/debug/PlotTurns.cpp
@@ -17,7 +17,16 @@ PlotTurns::PlotTurns(QWidget *parent) : QWidget(parent) {
 
 void PlotTurns::add(const Timestamp ts, const TurnData& data) {
 	(void) ts;
-	this->data = data;
+	this->turnData = data;
+	static int i = 0;
+	if (++i % 4 == 0) {
+		QMetaObject::invokeMethod(this, "update", Qt::QueuedConnection);
+	}
+}
+
+void PlotTurns::add(const Timestamp ts, const CompassData& data) {
+	(void) ts;
+	this->compassData = data;
 	static int i = 0;
 	if (++i % 4 == 0) {
 		QMetaObject::invokeMethod(this, "update", Qt::QueuedConnection);
@@ -35,17 +44,26 @@ void PlotTurns::paintEvent(QPaintEvent* evt) {
 	const float cx = width() / 2;
 	const float cy = height() / 2;
 
-	const float x1 = cx + std::cos(data.radSinceStart-M_PI_2) * s1;
-	const float y1 = cy + std::sin(data.radSinceStart-M_PI_2) * s1;
-
 	p.fillRect(0,0,width(),height(),QColor(255,255,255,192));
 	p.setPen(Qt::black);
 	p.drawRect(0,0,width()-1,height()-1);
 
-	const QPen pen(Qt::black, 2);
-	p.setPen(pen);
+	// turn [relative]
+	const float x1 = cx + std::cos(turnData.radSinceStart-M_PI_2) * s1;
+	const float y1 = cy + std::sin(turnData.radSinceStart-M_PI_2) * s1;
+	const QPen pen1(Qt::black, 2);
+	p.setPen(pen1);
 	p.drawLine(cx, cy, x1, y1);
 
+	// compass [absolute]
+	if (compassData.isValid()) {
+		const float x2 = cx + std::cos(compassData.azimuth) * s1;
+		const float y2 = cy + std::sin(compassData.azimuth) * s1;
+		const QPen pen2(Qt::gray, 2);
+		p.setPen(pen2);
+		p.drawLine(cx, cy, x2, y2);
+	}
+
 	p.end();
 
 }
diff --git a/ui/debug/PlotTurns.h b/ui/debug/PlotTurns.h
index 6cc3027..cf23b06 100644
--- a/ui/debug/PlotTurns.h
+++ b/ui/debug/PlotTurns.h
@@ -3,6 +3,8 @@
 
 #include <QWidget>
 #include "../sensors/TurnSensor.h"
+#include "../sensors/CompassSensor.h"
+
 #include <Indoor/data/Timestamp.h>
 
 class PlotTurns : public QWidget {
@@ -11,7 +13,8 @@ class PlotTurns : public QWidget {
 
 private:
 
-	TurnData data;
+	TurnData turnData;
+	CompassData compassData;
 
 public:
 
@@ -19,7 +22,7 @@ public:
 
 	void add(const Timestamp ts, const TurnData& data);
 
-	//QSize sizeHint() const {return QSize(96, 96);}
+	void add(const Timestamp ts, const CompassData& data);
 
 signals:
 
diff --git a/ui/debug/SensorDataWidget.cpp b/ui/debug/SensorDataWidget.cpp
index 9e8c14e..52037b9 100644
--- a/ui/debug/SensorDataWidget.cpp
+++ b/ui/debug/SensorDataWidget.cpp
@@ -7,6 +7,7 @@
 
 #include "../sensors/SensorFactory.h"
 #include "PlotTurns.h"
+#include "PlotGPS.h"
 #include "PlotWiFiScan.h"
 
 #include "../Settings.h"
@@ -196,14 +197,17 @@ SensorDataWidget::SensorDataWidget(QWidget* parent) : QWidget(parent) {
 	plotBaro = new PlotBaro(this);
 	plotTurn = new PlotTurns(this);
 	plotWiFi = new PlotWiFiScan(this);
+	plotGPS = new PlotGPS(this);
 
 	// layout setup
 	lay = new QGridLayout(this);
 	lay->addWidget(plotGyro,	0, 0, 1, 4);
 	lay->addWidget(plotAcc,		1, 0, 1, 4);
 	lay->addWidget(plotBaro,	2, 0, 1, 4);
+
 	lay->addWidget(plotTurn,	3, 0, 1, 1);
-	lay->addWidget(plotWiFi,	3, 1, 1, 3);
+	lay->addWidget(plotGPS,		3, 1, 1, 1);
+	lay->addWidget(plotWiFi,	3, 2, 1, 2);
 
 //	lay->setRowStretch(0, 1);
 //	lay->setRowStretch(1, 1);
@@ -221,6 +225,8 @@ SensorDataWidget::SensorDataWidget(QWidget* parent) : QWidget(parent) {
 	SensorFactory::get().getTurns().addListener(this);
 	SensorFactory::get().getWiFi().addListener(this);
 	SensorFactory::get().getActivity().addListener(this);
+	SensorFactory::get().getCompass().addListener(this);
+	SensorFactory::get().getGPS().addListener(this);
 
 }
 
@@ -257,6 +263,16 @@ void SensorDataWidget::onSensorData(Sensor<TurnData>* sensor, const Timestamp ts
 	((PlotTurns*)plotTurn)->add(ts, data);
 }
 
+void SensorDataWidget::onSensorData(Sensor<CompassData>* sensor, const Timestamp ts, const CompassData& data) {
+	(void) sensor;
+	((PlotTurns*)plotTurn)->add(ts, data);
+}
+
+void SensorDataWidget::onSensorData(Sensor<GPSData>* sensor, const Timestamp ts, const GPSData& data) {
+	(void) sensor;
+	((PlotGPS*)plotGPS)->add(ts, data);
+}
+
 void SensorDataWidget::onSensorData(Sensor<WiFiMeasurements>* sensor, const Timestamp ts, const WiFiMeasurements& data) {
 	(void) sensor;
 	((PlotWiFiScan*)plotWiFi)->add(ts, data);
diff --git a/ui/debug/SensorDataWidget.h b/ui/debug/SensorDataWidget.h
index 54d0d4a..61e8b22 100644
--- a/ui/debug/SensorDataWidget.h
+++ b/ui/debug/SensorDataWidget.h
@@ -13,6 +13,8 @@
 #include "../sensors/TurnSensor.h"
 #include "../sensors/WiFiSensor.h"
 #include "../sensors/ActivitySensor.h"
+#include "../sensors/GPSSensor.h"
+#include "../sensors/CompassSensor.h"
 
 class PlotWidget;
 class QGridLayout;
@@ -26,7 +28,9 @@ class SensorDataWidget :
 		public SensorListener<ActivityData>,
 		public SensorListener<StepData>,
 		public SensorListener<TurnData>,
-		public SensorListener<WiFiMeasurements> {
+		public SensorListener<WiFiMeasurements>,
+		public SensorListener<GPSData>,
+		public SensorListener<CompassData> {
 
 
 	Q_OBJECT
@@ -43,18 +47,21 @@ public:
 	void onSensorData(Sensor<TurnData>* sensor, const Timestamp ts, const TurnData& data) override;
 	void onSensorData(Sensor<WiFiMeasurements>* sensor, const Timestamp ts, const WiFiMeasurements& data) override;
 	void onSensorData(Sensor<ActivityData>* sensor, const Timestamp ts, const ActivityData& data) override;
+	void onSensorData(Sensor<GPSData>* sensor, const Timestamp ts, const GPSData& data) override;
+	void onSensorData(Sensor<CompassData>* sensor, const Timestamp ts, const CompassData& data) override;
 
 private:
 
 	PlotWidget* plotGyro;
 	PlotWidget* plotAcc;
 	PlotWidget* plotBaro;
+
 	QWidget* plotTurn;
 	QWidget* plotWiFi;
+	QWidget* plotGPS;
 
 	QGridLayout* lay;
 
-
 };
 
 #endif // SENSORDATAWIDGET_H
diff --git a/ui/debug/plot/PlottWidget.h b/ui/debug/plot/PlottWidget.h
index 6c4d84a..119c368 100644
--- a/ui/debug/plot/PlottWidget.h
+++ b/ui/debug/plot/PlottWidget.h
@@ -2,6 +2,7 @@
 #define PLOTTI_H
 
 #include <QWidget>
+#include "../misc/fixc11.h"
 #include "Plot.h"
 
 /** widget to render one plot */
diff --git a/yasmin.pro b/yasmin.pro
index dd0e86b..2c74380 100644
--- a/yasmin.pro
+++ b/yasmin.pro
@@ -9,6 +9,7 @@ QT += qml opengl svg
 ANDROID {
     QT += androidextras
     QT += sensors
+    QT += positioning
 
     #http://stackoverflow.com/questions/28391685/opencv-with-hard-float-support-for-android#28393545
     # wasn't faster... and seems dangerous :P
@@ -78,7 +79,8 @@ SOURCES += \
     ui/debug/InfoWidget.cpp \
     ui/map/3D/MapView3D.cpp \
     ui/map/2D/MapView2D.cpp \
-    tools/calibration/WiFiCalibrationScanDialog.cpp
+    tools/calibration/WiFiCalibrationScanDialog.cpp \
+    ui/debug/PlotGPS.cpp
 
 RESOURCES += qml.qrc
 
@@ -183,7 +185,15 @@ HEADERS += \
     ipin/IPINHelper.h \
     nav/NavControllerListener.h \
     ipin/StepLoggerWrapper.h \
-    ipin/StepLoggerWrapperAndroid.h
+    ipin/StepLoggerWrapperAndroid.h \
+    sensors/GPSSensor.h \
+    sensors/android/GPSSensorAndroid.h \
+    sensors/CompassSensor.h \
+    sensors/android/CompassSensorAndroid.h \
+    sensors/dummy/CompassSensorDummy.h \
+    sensors/dummy/GPSSensorDummy.h \
+    ui/debug/PlotGPS.h \
+    sensors/SensorWriter.h
 
 DISTFILES += \
     android-sources/src/MyActivity.java \