This is a recording of a chirpsounder, similar to the AN/TRQ-35, zipping through the 17 meter ham band. These sounders can start at 2 or 3 MHz and run up to 28+ MHz at rates of 100 kHz or more per second. They are used to map atmospheric responses and determine propagation for other HF systems, such as communications networks and HF radars.
httpv://www.youtube.com/watch?v=B0EwS45ZZbo
