Love this story, found it in the May 2014 QST Magazine.
Mystery signal from a helicopter: “Last night, YouTube suggested a video for me. It was a raw clip from a news helicopter filming a police chase in Kansas City, Missouri. I quickly noticed a weird interference in the audio, especially the left channel, and thought it must be caused by the chopper’s engine. I turned up the volume and realized it’s not interference at all, but a mysterious digital signal! And off we went again.
What could it be? Location telemetry from the helicopter? Information about the camera direction? Video timestamps?”