   if (!radio.write( &tx_payload, sizeof(tx_t))) {
     // Got no ack.
     if (DEBUG) {
-      printf("no ack.\n\r"); 
+      //printf("no ack.\n\r"); 
+      ++ppsLostCounter;
     }
   } else {
      if (!radio.available()) { 

          radio.read( &ack_payload, sizeof(ack_t) );
          ppsCounter++;
          if (DEBUG) {
            printf("Got response %d, pps: %d , round-trip: %lu microseconds\n\r", ack_payload.val, pps, tim-time);
          }
        }



void loop(void)
{
  tx_payload.throttle = joystickMapValues( analogRead(PIN_THROTTLE), 100, 500, 900, false );
  tx_payload.yaw      = joystickMapValues( analogRead(PIN_YAW), 100, 500, 900, false );
  tx_payload.pitch    = joystickMapValues( analogRead(PIN_PITCH), 100, 500, 900, false );
  tx_payload.roll     = joystickMapValues( analogRead(PIN_ROLL), 100, 500, 900, false );
   
  if (DEBUG) {
    //printf("Now sending throttle %d\n\r ",tx_payload.throttle);
  }
  
  // Stop listening so we can talk.
  radio.stopListening();                                  
