Listen to the transmit frequency with an FM (narrow band) radio. You will hear the 9600 baud packets if there are being sent over the air. If you don't have a FM radio, you can purchase a Beofang radio (amateur radio) for under $40. Of course you need license for the frequency you are using; amateur radio license if you are using the amateur frequencies.
Or, configure one Hamshield to receive FM and you will hear the same noise if packets are sent over the air. That will take a new sketch.