Superpulse

Superpulse is a term for very strong man-made radio signals. The two most common instances of superpulses are those transmitted by the VLF transmitter GBZ, and occasionally by an unidentified station on 17.8 kHz. The purpose of superpulses is unknown, but they are believed to be an element of an obsolete sound-based navigational system. Another theory states that the pulses are the product of frequency instability causing arcing resulting in a broadband pulse of interference . Superpulses can overdrive the front-end amplifier of a PC several hundred kilometres away from the transmitter, when a PC with an aerial attached to its soundcard is used as a VLF receiver.