Wind/WAVES observations of man-made radio transmissions

The WAVES radio and plasma wave instrument on the Wind spacecraft, launched on November 1, 1994, has detected copious shortwave radio transmissions from broadcast stations on Earth. WAVES can easily detect signals consisting of only a few kW of transmitted power, suggesting that useful ionospheric propagation research can be accomplished with very modest equipment. We also conclude that the terrestrial radio spectrum is quite ''non natural'' so that any extraterrestrial radio astronomer should easily deduce that Earth is populated with a civilization with technical capabilities.