GBZ is the callsign of a British VLF transmitter, which transmits on 19.6 kHz from Anthorn, Cumbria (formerly from Criggion, Powys) encoded signals to submarines. Although the signals of GBZ cannot be decoded by common means, its reception - if its signal is shown in form of spectrograms - is very interesting, because the signals of GBZ show figures looking like fishes, garlands and ornaments on the spectrograms. At certain times these signals are also transmitted as strong pulses, so-called superpulses, which can oversteer the amplifier of a PC soundcard at distances of a hundred kilometres away from transmission site.

External links

• http://www.vlf.it/harald/strangerec.htm
• http://www.vlf.it/trond2/15-20khz.html
• Spectrogram of superpulse

Military radio systems

GBZ