diff --git a/src/coona.cpp b/src/coona.cpp
new file mode 100644
index 00000000..44020d84
--- /dev/null
+++ b/src/coona.cpp
@@ -0,0 +1,85 @@
+// routines for counting the number of available Corona Warn Apps (CWA)
+
+// copied from https://github.com/kmetz/BLEExposureNotificationBeeper
+// (c) by Kaspar Metz
+// modified for use in the Paxcounter by AQ
+
+#if (COUNT_CWA)
+
+// Local logging tag
+static const char TAG[] = __FILE__;
+
+#define BT_BD_ADDR_HEX(addr)                                                   \
+  addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]
+
+#include "corona.h"
+
+// taken from macsniff.cpp
+extern uint16_t salt;    
+extern uint16_t hashedmac;
+
+// When to forget old senders.
+#define FORGET_AFTER_MINUTES 2
+
+static std::map<uint16_t, unsigned long> cwaSeenNotifiers;
+
+
+/**
+ * Remove notifiers last seen over FORGET_AFTER_MINUTES ago.
+ */
+void cwa_clear() {
+  ESP_LOGD(TAG, "CWA: forget old notifier: %d", cwaSeenNotifiers.size());
+
+//#ifdef SOME_FORM_OF_DEBUG
+  for (auto const &notifier : cwaSeenNotifiers) {
+      ESP_LOGI(TAG, "CWA forget <%X>", notifier.first);
+//    }
+  }
+//#endif
+    /* clear everything,
+     * otherwise we will count the same device again
+     * as in the next cycle it will get a differetn hash-value
+     */
+    cwaSeenNotifiers.clear();  
+}
+
+/* return the numbers of active CWAs found
+ */
+uint16_t cwa_report(void) {
+  return cwaSeenNotifiers.size();
+}
+
+bool cwa_init(void)
+{
+  ESP_LOGD(TAG, "init of BLE-scanner for CWA");
+  return true;
+
+}
+
+// similar to mac_add(), found in macsniff.cpp
+// for comments pls. look into this function
+bool cwa_mac_add(uint8_t* paddr) {
+  
+  // are we too early?
+  if ( hashedmac <= 0 )
+      return false;   // YES -> return
+
+  bool added = false;
+  ESP_LOGD(TAG, "Device address (bda): %02x:%02x:%02x:%02x:%02x:%02x",
+               BT_BD_ADDR_HEX(paddr));
+  
+  ESP_LOGD(TAG, "hasehd mac = %X, count = %d (total=%d)", hashedmac, cwaSeenNotifiers.count(hashedmac), cwaSeenNotifiers.size());
+    added = !(cwaSeenNotifiers.count(hashedmac) > 0);
+
+    // Count only if MAC was not yet seen
+    if (added) {
+        ESP_LOGD(TAG, "added device with active CWA");
+   }
+
+   cwaSeenNotifiers[hashedmac] = millis(); // last seen at ....
+
+  // True if MAC WiFi/BLE was new
+  return added; 
+}
+
+#endif