on off keying (OOK)

On-Off keying (OOK) is a carrier shift keying method in which the carrier signal is switched on and off.

On-Off keying is the simplest form of amplitude shift keying. If a carrier frequency is present, this corresponds to a digital "1"; if none is present, it is a digital "0". On-Off keying is not very efficient with respect to the frequency spectrum and cannot distinguish between "zeros" and interrupts. It is used in Morse code, in optical transmission technology and in some WPAN technologies in the 2.4 GHz band.