When the Juno spacecraft recently did a fly-by of earth on its way to Jupiter, amateur radio enthusiasts were urged to try to contact Juno. This brief documentary video describes the successful project:
http://youtu.be/_yqHy_MpNiQ
Caption:
During its close flyby of Earth, NASA’s Jupiter-bound Juno spacecraft listened for a communication from amateur radio operators transmitting from locations around the world. This video clip depicts results, the “dits” and the “dahs,” of this high-flying social experiment.
And this short video displays the signals : Juno Detects a Ham Radio “HI” from Earth – NASA JPL Photojournal