Working a pileup on 20M today, saw something odd. A station was sending his callsign as an image on my spectrum display. Moved up band and contacted him. He said it was a function he had added to his SDR radio. Burst of tones on SSB and the callsign appears on the waterfall display of the spectrum scope until it drifts down out of sight. That seemed cool. I was using plus or minus 25 kHz on my display and he was running a little over 3 kHz of transmit bandwidth setting. So in a wide sweep it would be unnoticed. The sweep needs to be narrow enough that his transmit B/W is easily visible over a segment but probably would be distorted on a very narrow spectrum where the signal filled up too much of the sweep. Seems an interesting use of SSB now that many of us have spectrum displays.