diff --git a/config.h b/config.h
index 03a4491..142e70a 100644
--- a/config.h
+++ b/config.h
@@ -3,7 +3,9 @@
 /* WiFi (ESP8266) */
 
 
-#define WIFI_SSID "Penaten"
+
+
+#define WIFI_SSID "FRITZ!Box 7490"
 #define WIFI_PASS "XXXXXX"
 
 /* GPS reciever (uBloc NEO-7M) */
@@ -19,6 +21,8 @@
 #define API_KEY_LENGTH 24
 #define API_KEY "XXXXXXXXXXX"
 #define ID_BOX "57c7f3291421551100bf13c8"
-#define ID_SENSOR_WIFI "57c7f3291421551100bf13ca"
+#define ID_SENSOR_WIFI_APS "57c7f3291421551100bf13ca"
+#define ID_SENSOR_WIFI_NET "57cdd4ce1421551100bf17c5"
+#define ID_SENSOR_WIFI_OPEN "57cdd4ce1421551100bf17c6"
 
-#define MEASUREMENT_INTERVAL 10000
+#define MEASUREMENT_INTERVAL 20000
diff --git a/mobile-sensebox.ino b/mobile-sensebox.ino
index 87f7b0b..3f7a44c 100644
--- a/mobile-sensebox.ino
+++ b/mobile-sensebox.ino
@@ -108,6 +108,7 @@ void loop() {
 
   // print state
   DEBUG_OUT << "homeAvailable:  " << wifiState.homeAvailable << EOL;
+  DEBUG_OUT << "numAPs:         " << wifiState.numAccessPoints << EOL;
   DEBUG_OUT << "numNetworks:    " << wifiState.numNetworks << EOL;
   DEBUG_OUT << "numUnencrypted: " << wifiState.numUnencrypted << EOL;
   DEBUG_OUT.print("lat: ");
@@ -116,18 +117,32 @@ void loop() {
   DEBUG_OUT.println(loc.lng(), 6);
   DEBUG_OUT << dateString << EOL;
 
+  // TODO. write location update to file  
+  
   // write measurements to file
-  if (storeMeasurement(loc.lat(), loc.lng(), wifiState.numNetworks, dateString, ID_SENSOR_WIFI)) {
-    DEBUG_OUT.print("measurement (wifi) stored! storage size: ");
+  if (storeMeasurement(loc.lat(), loc.lng(), wifiState.numAccessPoints, dateString, ID_SENSOR_WIFI_APS)) {
+    DEBUG_OUT.print("measurement (wifi aps) stored! storage size: ");
   } else {
-    DEBUG_OUT.print("measurement (wifi) store failed! storage size: ");
+    DEBUG_OUT.print("measurement (wifi aps) store failed! storage size: ");
   }
   DEBUG_OUT.println(storage.size());
-
+  if (storeMeasurement(loc.lat(), loc.lng(), wifiState.numNetworks, dateString, ID_SENSOR_WIFI_NET)) {
+    DEBUG_OUT.print("measurement (wifi nets) stored! storage size: ");
+  } else {
+    DEBUG_OUT.print("measurement (wifi nets) store failed! storage size: ");
+  }
+  DEBUG_OUT.println(storage.size());
+  if (storeMeasurement(loc.lat(), loc.lng(), wifiState.numUnencrypted, dateString, ID_SENSOR_WIFI_OPEN)) {
+    DEBUG_OUT.print("measurement (wifi open) stored! storage size: ");
+  } else {
+    DEBUG_OUT.print("measurement (wifi open) store failed! storage size: ");
+  }
+  DEBUG_OUT.println(storage.size());
+  
   // connect to wifi, if available & not connected yet
-  // once we are connected, upload (max) 3 stored measurements & free the storage
+  // once we are connected, upload (max) 4 stored measurements & free the storage
   if (wifi.isConnected() || (wifiState.homeAvailable && wifi.connect(WIFI_SSID, WIFI_PASS)) ) {
-    uploadMeasurements(3);  
+    uploadMeasurements(4);  
   }
   
   DEBUG_OUT << EOL;
diff --git a/wifi.h b/wifi.h
index 8db0aaf..33a755b 100644
--- a/wifi.h
+++ b/wifi.h
@@ -4,6 +4,7 @@
 
 struct WifiState {
   bool homeAvailable;
+  unsigned int numAccessPoints;
   unsigned int numNetworks;
   unsigned int numUnencrypted;
 };
@@ -15,20 +16,37 @@ class Wifi {
   }
   
   WifiState scan(String homeSSID) {
-    // TODO: filter duplicate SSIDs!
     WifiState state;
-    state.homeAvailable = false;
-    state.numNetworks = WiFi.scanNetworks(false, false);
+    int n = WiFi.scanNetworks(false,false);
+    state.numAccessPoints = n;
+    state.numNetworks = n;
     state.numUnencrypted = 0;
+    state.homeAvailable = false;
+    int indices[n];
+    String ssid;
+    
+    for (int i = 0; i < n; i++) indices[i] = i;
+
+    for (int i = 0; i < n; i++) {
+      // filter duplicates
+      if(indices[i] == -1) {
+        --state.numNetworks;
+        continue;
+      }
+      ssid = WiFi.SSID(indices[i]);
+      for (int j = i + 1; j < n; j++) {
+        if (ssid == WiFi.SSID(indices[j])) indices[j] = -1;
+      }
+      
+      if (indices[i] != -1) {
+        if (WiFi.encryptionType(indices[i]) == ENC_TYPE_NONE)
+          ++state.numUnencrypted;
   
-    for (unsigned int i = 0; i < state.numNetworks; i++) {
-      if (WiFi.encryptionType(i) == ENC_TYPE_NONE)
-        ++state.numUnencrypted;
-  
-      if (WiFi.SSID(i) == homeSSID)
-        state.homeAvailable = true;
+        if (WiFi.SSID(indices[i]) == homeSSID)
+          state.homeAvailable = true;
+      }
     }
-  
+    
     return state;
   }