On-off keying

On-off keying (OOK) the simplest form of amplitude-shift keying (ASK) modulation that represents digital data as the presence or absence of a carrier wave. In its simplest form, the presence of a carrier for a specific duration represents a binary one, while its absence for the same duration represents a binary zero. Some more sophisticated schemes vary these durations to convey additional information. It is analogous to unipolar encoding line code.

On-off keying is most commonly used to transmit Morse code over radio frequencies (referred to as continuous wave operation), although in principle any digital encoding scheme may be used. OOK has been used in the ISM bands to transfer data between computers, for example.

OOK is more spectrally efficient than FSK, but more sensitive to noise.

In addition to RF carrier waves, OOK is also used in optical communication systems (e.g. IrDA).

In aviation, some possibly unmanned airports have equipment that let pilots key their VHF radio a number of times in order to request an Automatic Terminal Information Service broadcast, or turn on runway lights.

See also

• Unipolar encoding

External links

• Application Note - I'm OOK. You're OOK?

v • d • e Pulse-code modulation (PCM) digital encoding Main articles Unipolar encoding · Bipolar encoding · On-off keying Basic line codes Return to zero (RZ) · Non-return-to-zero, level (NRZ/NRZ-L) · Non-return-to-zero, inverted (NRZ-I) · Non-Return-to-Zero, space (NRZ-S) · Biphase (Bi-φ) · Manchester · Differential Manchester Extended line codes Conditioned Diphase · 4B3T · 4B5B · AMI code · Modified AMI code · Coded mark inversion · MLT-3 encoding · Hybrid ternary code · 6b/8b encoding · 8b/10b encoding · 64b/66b encoding · Eight-to-fourteen modulation · Delay/Miller encoding · TC-PAM Optical line codes Carrier-Suppressed Return-to-Zero · Alternate-Phase Return-to-Zero See also: Quantization · Sampling · Category:Line codes