diff --git a/cubesatsim/cubesatsim.ino b/cubesatsim/cubesatsim.ino
index 1e224e05..a201adcb 100644
--- a/cubesatsim/cubesatsim.ino
+++ b/cubesatsim/cubesatsim.ino
@@ -175,7 +175,7 @@ void setup() {
 /**/
 //  Serial.println("Transmitting callsign");	
 //  strcpy(callsign, call);	
-  if (mode != CW)
+  if ((mode != CW)  || (!filter_present))
     transmit_callsign(callsign);
 //  sleep(5.0);		
   sleep(1.0);