One of the sounds in my first soundpack for xonotic (http://xonotic. Org). Synthesized with zynaddsubfx inside lmms, edited in audacity. Long live linux!.
Sine signal of 1000hz generated to -20db of peak with a duration of 1 second to 25 frame/sec (pal (europe, uruguay, argentina, australia), secam, dvb, atsc).