NJDTechnologies

Radio: it's not just a hobby, it's a way of life

Current Operating Frequency and Mode

OFF AIR

SCHEDULED ACTIVITY: CQ 474.5 kHz CW by 0020z through sunset

VLF birds!

– Posted in: 630 Meter General Topics, 630 Meters

No, its not a new game for your IPhone! Its not even really related to the 630-meter band but its very cool nonetheless.

This recording is long, maybe 9-minutes, and there is no real reason to listen to all of it unless you just want to.

Hear the birds singing?  There is no microphone!  This recording, provided by Paul Nicholson on the VLF Yahoo Group, shows how high gain audio frequency amplifiers and probe antennas can be almost as sensitive to audio frequency vibrations as a conventional microphone.  Now this find won’t replace your Heil, Sennheiser, or RE20 microphones for broadcast quality audio but it is an amazing application of physics.

Also of note are the crackles and pops from sferics and the song from the sun.  Make no mistake about it – you are listening to RF signals and the birds are contributing to the show by vibrating the air around the antenna, oscillating the surrounding electric field that results in this incredible audio.