diff --git a/.idea/caches/build_file_checksums.ser b/.idea/caches/build_file_checksums.ser
index 35a854e..7151dc7 100644
Binary files a/.idea/caches/build_file_checksums.ser and b/.idea/caches/build_file_checksums.ser differ
diff --git a/app/build.gradle b/app/build.gradle
index 0c03cdc..cec079c 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -7,7 +7,7 @@ android {
     defaultConfig {
         applicationId "de.fhws.indoor.sensorreadout"
         minSdkVersion 21
-        targetSdkVersion 23
+        targetSdkVersion 28
         versionCode 1
         versionName "1.0"
         multiDexEnabled true
diff --git a/app/src/main/java/de/fhws/indoor/sensorreadout/MainActivity.java b/app/src/main/java/de/fhws/indoor/sensorreadout/MainActivity.java
index f3a2941..be4d8cb 100644
--- a/app/src/main/java/de/fhws/indoor/sensorreadout/MainActivity.java
+++ b/app/src/main/java/de/fhws/indoor/sensorreadout/MainActivity.java
@@ -490,7 +490,7 @@ public class MainActivity extends AppCompatActivity {
         }
         if(activeSensors.contains("WIFI")) {
             boolean useWifiFtm = preferences.getBoolean("prefUseWifiFTM", false);
-            if(useWifiFtm && WiFiRTT.isSupported()) {
+            if(useWifiFtm && WiFiRTT.isSupported(this)) {
                 Log.i("Sensors", "Using Wifi[FTM]");
                 // log wifi RTT using sensor number 17
                 final WiFiRTT wifirtt = new WiFiRTT(this);
diff --git a/app/src/main/java/de/fhws/indoor/sensorreadout/SettingsFragment.java b/app/src/main/java/de/fhws/indoor/sensorreadout/SettingsFragment.java
index a9243f2..b509d62 100644
--- a/app/src/main/java/de/fhws/indoor/sensorreadout/SettingsFragment.java
+++ b/app/src/main/java/de/fhws/indoor/sensorreadout/SettingsFragment.java
@@ -11,7 +11,7 @@ public class SettingsFragment extends PreferenceFragmentCompat {
     @Override
     public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
         setPreferencesFromResource(R.xml.preferences, rootKey);
-        if(!WiFiRTT.isSupported()) {
+        if(!WiFiRTT.isSupported(getContext())) {
             SwitchPreferenceCompat useFtmPreference = (SwitchPreferenceCompat)findPreference("prefUseWifiFTM");
             useFtmPreference.setEnabled(false);
         }
diff --git a/app/src/main/java/de/fhws/indoor/sensorreadout/sensors/WiFiRTT.java b/app/src/main/java/de/fhws/indoor/sensorreadout/sensors/WiFiRTT.java
index 3cfdd58..baa7f1b 100644
--- a/app/src/main/java/de/fhws/indoor/sensorreadout/sensors/WiFiRTT.java
+++ b/app/src/main/java/de/fhws/indoor/sensorreadout/sensors/WiFiRTT.java
@@ -12,6 +12,8 @@ import android.net.wifi.rtt.RangingRequest;
 import android.net.wifi.rtt.RangingResult;
 import android.net.wifi.rtt.RangingResultCallback;
 import android.net.wifi.rtt.WifiRttManager;
+
+import androidx.annotation.RequiresApi;
 import androidx.core.app.ActivityCompat;
 
 import android.os.Build;
@@ -163,10 +165,15 @@ public class WiFiRTT extends mySensor {
         }
     };
 
-    public static final boolean isSupported() {
-        return (Build.VERSION.SDK_INT >= 28);
-
-        //TODO markusb Implement a proper test for whether FTM is supported
-        // If this needs a context / activity, no problem
+    @RequiresApi(api = Build.VERSION_CODES.P)
+    public static final boolean isSupported(Context context) {
+        if(!context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_WIFI_RTT)) {
+            return false;
+        }
+        WifiRttManager rttManager = (WifiRttManager) context.getSystemService(Context.WIFI_RTT_RANGING_SERVICE);
+        if(rttManager == null) {
+            return false;
+        }
+        return rttManager.isAvailable();
     }
 }