Superpulse is the name for very strong radio signals, which are transmitted by the VLF transmitter GBZ and by an unidentified station on 17.8 kHz at certain times. The purpose of superpulses is unknown. Superpulses can oversteer the entrance amplifier of PCs in distances until some hundred kilometres away from the transmitter, if the PC is used with an aerial at its soundcard as a VLF receiver.