National Parks on the Air map
In cooperation with the American Radio Relay League (ARRL) CQmaps is pleased to offer the 2016 National Parks on the Air (NPOTA) map. Your map is the ticket to all 432 parks that the ARRL has included in the 2016 Centennial. CQmaps
Arduino pocket lightning detector
This sensor watches for the particular waveform of lightning at 500Khz and gives a distance approximation. Instructables
TV going the distance: Propagation
At shortwave frequencies, distant propagation is much more common. Shortwaves travel via ground wave (short distance) and sky wave. Hack A Day
HF Underground
Shortwave Pirate Radio Forums in North America and Around The World. (And other stations that go bump in the night.) HF Underground
Duga radar (Russian Woodpecker)
Duga-1 was a Soviet over-the-horizon (OTH) radar system used as part of the Soviet ABM early-warning network. Wikipedia
Sound clip of Russian Woodpecker
It sounded like a sharp, repetitive tapping noise, at 10 Hz, giving rise to the "Woodpecker" name. YouTube