diff --git a/Controller.cpp b/Controller.cpp
index 2541e39..b33a728 100644
--- a/Controller.cpp
+++ b/Controller.cpp
@@ -51,9 +51,9 @@ Controller::Controller() : sl(scaler) {
 
 	//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"));
 
-//	SensorFactory::set(new SensorFactoryAndroid());
+SensorFactory::set(new SensorFactoryAndroid());
 //	SensorFactory::get().getAccelerometer().start();
 //	SensorFactory::get().getGyroscope().start();
 //	SensorFactory::get().getBarometer().start();
diff --git a/Settings.h b/Settings.h
index 2832ba7..c403a35 100644
--- a/Settings.h
+++ b/Settings.h
@@ -13,7 +13,7 @@ namespace Settings {
 	namespace IMU {
 		const float turnSigma = 1.5;		// 3.5
 		const float stepLength = 0.80;
-		const float stepSigma = 0.10;
+		const float stepSigma = 0.20;
 	}
 
 	const float smartphoneAboveGround = 1.3;
@@ -33,7 +33,7 @@ namespace Settings {
 	}
 
 	namespace WiFiModel {
-		constexpr float sigma = 11.0;
+		constexpr float sigma = 13.0;
 		/** if the wifi-signal-strengths are stored on the grid-nodes, this needs a grid rebuild! */
 		constexpr float TXP = -48;
 		constexpr float EXP = 2.5;
diff --git a/_android/src/MyActivity.java b/_android/src/MyActivity.java
index 62c4dda..85e3b79 100644
--- a/_android/src/MyActivity.java
+++ b/_android/src/MyActivity.java
@@ -1,6 +1,7 @@
 package indoor.java;
 
 import android.os.Bundle;
+import android.view.WindowManager;
 import org.qtproject.qt5.android.bindings.QtActivity;
 
 public class MyActivity extends QtActivity {
@@ -13,9 +14,13 @@ public class MyActivity extends QtActivity {
 
     @Override
     public void onCreate(Bundle savedState) {
+
         MyActivity.act = this;
         super.onCreate(savedState);
 
+		// prevent power-safe?
+		getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
+
 		// IPIN2016
 		stepLogger = new StepLoggerClient(this);
 
diff --git a/_android/src/WiFi.java b/_android/src/WiFi.java
index 450d7f3..47b5b37 100644
--- a/_android/src/WiFi.java
+++ b/_android/src/WiFi.java
@@ -50,7 +50,7 @@ public class WiFi {
         // start the first scan
         triggerOneScan();
 
-        return 0;
+		return 1337;
 
     }
 
diff --git a/nav/Filter.h b/nav/Filter.h
index 47384c1..49df991 100644
--- a/nav/Filter.h
+++ b/nav/Filter.h
@@ -215,11 +215,14 @@ public:
 		const MyObservation observation = _observation;
 
 		// vap-grouping
+		const int numAP1 = observation.wifi.entries.size();
 		const WiFiMeasurements wifiObs = vg.group(_observation.wifi);
+		const int numAP2 = wifiObs.entries.size();
+
+		Log::add("Filter", "VAP: " + std::to_string(numAP1) + " -> " + std::to_string(numAP2));
 
 		for (K::Particle<MyState>& p : particles) {
 
-
 			// WiFi free
 			//const double pWiFi = wiFiProbability.getProbability(p.state.position.inMeter()+person, observation.currentTime, vg.group(observation.wifi));
 
@@ -227,9 +230,12 @@ public:
 			const MyGridNode& node = grid->getNodeFor(p.state.position);
 			const double pWiFi = wiFiProbability.getProbability(node, observation.currentTime, wifiObs);
 
+			//Log::add("xxx", std::to_string(observation.currentTime.ms()) + "_" + std::to_string(wifiObs.entries[0].ts.ms()));
+
 			const double pStair = getStairProb(p, observation.activity);
 			const double pGPS = 1;
 			const double prob = pWiFi * pGPS * pStair;
+
 			p.weight *= prob;		// NOTE: keeps the weight returned by the transition step!
 			//p.weight = prob;		// does NOT keep the weights returned by the transition step
 			sum += p.weight;
diff --git a/sensors/android/WiFiSensorAndroid.h b/sensors/android/WiFiSensorAndroid.h
index 1160e85..40c37b8 100644
--- a/sensors/android/WiFiSensorAndroid.h
+++ b/sensors/android/WiFiSensorAndroid.h
@@ -28,9 +28,12 @@ public:
 
 	void start() override {
 
+		// do NOT start twice!
+		if (started) {return;}
+
 		// start scanning
 		int res = QAndroidJniObject::callStaticMethod<int>("indoor/java/WiFi", "start", "()I");
-		if (res != 0) {throw Exception("error while starting WiFi");}
+		if (res != 1337) {throw Exception("error while starting WiFi");}
 		started = true;
 
 	}
@@ -49,6 +52,9 @@ public:
 		// to-be-constructed sensor data
 		WiFiMeasurements sensorData;
 
+		// tag all scan-entries with the current app runtime
+		const Timestamp curTS = Timestamp::fromRunningTime();
+
 		// parse each mac->rssi entry
 		for (int i = 0; i < (int)data.length(); i += 17+1+2) {
 			const std::string bssid = data.substr(i, 17);
@@ -56,7 +62,7 @@ public:
 			const int8_t pad1 = data[i+18];
 			const int8_t pad2 = data[i+19];
 			if (pad1 != 0 || pad2 != 0) {Debug::error("padding error within WiFi scan result");}
-			sensorData.entries.push_back(WiFiMeasurement(AccessPoint(bssid), rssi));
+			sensorData.entries.push_back(WiFiMeasurement(AccessPoint(bssid), rssi, curTS));
 		}
 
 		// call listeners
diff --git a/tools/calibration/WiFiCalibrationScanDialog.h b/tools/calibration/WiFiCalibrationScanDialog.h
index 2999e11..840a708 100644
--- a/tools/calibration/WiFiCalibrationScanDialog.h
+++ b/tools/calibration/WiFiCalibrationScanDialog.h
@@ -28,7 +28,7 @@ private:
 	QProgressBar* barProg;
 
 	struct Scan {
-		const int numRecords = 10;
+		const int numRecords = 30;
 		int recordsDone = 0;
 	} scan;
 
diff --git a/ui/LoggerUI.h b/ui/LoggerUI.h
index b91beb2..319fa09 100644
--- a/ui/LoggerUI.h
+++ b/ui/LoggerUI.h
@@ -11,7 +11,7 @@ class LoggerUI : public Logger {
 private:
 
 	InfoWidget* iw;
-
+	const int numLines = 5;
 	std::vector<QString> lines;
 
 public:
@@ -24,7 +24,7 @@ public:
 	void add(const std::string& str, const bool nl) override {
 		lines.back() += QString(str.c_str());
 		if (nl) {lines.push_back("");}
-		while(lines.size() > 4) {lines.erase(lines.begin());}
+		while(lines.size() > numLines) {lines.erase(lines.begin());}
 		QString qs = getStr();
 		QMetaObject::invokeMethod(iw, "showLog", Qt::QueuedConnection, Q_ARG(const QString&, qs));
 		QApplication::processEvents();
diff --git a/ui/map/2D/MapView2D.cpp b/ui/map/2D/MapView2D.cpp
index e0bc644..d183f10 100644
--- a/ui/map/2D/MapView2D.cpp
+++ b/ui/map/2D/MapView2D.cpp
@@ -158,10 +158,12 @@ void MapView2D::mouseReleaseEvent(QMouseEvent* evt) {
 
 	const Point2 p1(evt->x(), evt->y());
 
+	// fingerprint node pressed?
+	const int fpSize = UIHelper::isLarge(this->parent()) ? (40) : (25);
 	int idx = 0;
 	for (const Point2 p2 : wifiCalib->getNodes()) {
 		const float dist = p1.getDistance(p2);
-		if (dist < 25) { wifiCalib->selectNode(idx); emit update(); break; }
+		if (dist < fpSize) { wifiCalib->selectNode(idx); emit update(); break; }
 		++idx;
 	}