Mode, you raise a valid concern. People who have these systems should not just randomly switch frequencies. Getting the correct frequency pin is critical. Polks has done something interesting to prevent shoot downs. When the transmitter is first turned on, it scans the current frequency. If it detects someone already on that frequency, it won't send a signal. Of course this doesn't prevent the owner of one of these from forgetting to get the pin, being up in the air and someone else shooting him down, but that would be his fault for not getting the pin.