Long-delayed-echoes are radio signals that return to the transmitting site after several seconds. Recently on around 7000kHz a German radio amateur heard his own signal coming back about 45 seconds after he had finished transmitting using morse code.
It normally takes around 1/7th second (0.14s) for a radio signal to go right round the Earth bouncing between the ionosphere and the planet to get back to where it started.
Did the signals just go round the world a few hundred times? The recording doesn't show them. You can hear them as .wav files here: http://brogl.net/Audio/
Also I'm interested in how they were audible after travelling for such a long distance. Was there some sort of focussing going on?
