* On-off keying ( OOK ), the most common ASK form

Eye diagram showing an example of two power levels in an On-off keying | OOK modulation scheme which can be used to calculate extinction ratio.

Graphical eye pattern showing an example of two power levels in an On-off keying | OOK modulation scheme.

On-off keying has been the commonly used modulation format in optical communications.

* 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.

it: On-off keying

# REDIRECT On-off keying

* On-off keying

On-off control will work where the overall system has a relatively long response time, but will result in instability if the system being controlled has a rapid response time.

A simple form of AM, often used for digital communications, is on-off keying: a type of amplitude-shift keying in which binary data is represented by the presence or absence of a carrier.

Microwriting is the system of chord keying and is based on a set of mnemonics.

Indeed, MSK is a particular case of the sub-family of CPM known as continuous-phase frequency-shift keying ( CPFSK ) which is defined by a rectangular frequency pulse ( i. e. a linearly increasing phase pulse ) of one symbol-time duration ( total response signaling ).

* The use of on-off keying to transmit Morse code at radio frequencies is known as continuous wave ( CW ) operation.

Once connected to the access number, the account is identified by keying in a PIN ( the most popular method ) or by swiping a card with embedded chip or magnetic stripe.

The modulated waves are summed, and the resulting waveform is a combination of both phase-shift keying ( PSK ) and amplitude-shift keying ( ASK ), or ( in the analog case ) of phase modulation ( PM ) and amplitude modulation.

Wireless telegraphy is also known as " CW ", for continuous wave ( a carrier modulated by on-off keying ), as opposed to the earlier radio technique of using a spark gap.

# In the transmission of binary or teletypewriter signals, keying in which the carrier frequency is shifted in one direction for marking signals and in the opposite direction for spacing signals.

Thus, if a " 1 " is represented by one transition, then a " 0 " is represented by two transitions and vice versa, making Differential Manchester a form of frequency shift keying.

In telegraphy, frequency-exchange signaling or two-source frequency keying is frequency-change signaling in which the change from one significant condition to another is accompanied by decay in amplitude of one or more frequencies and by buildup in amplitude of one or more other frequencies.

Frequency-shift keying ( FSK ) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave.

Minimum frequency-shift keying or minimum-shift keying ( MSK ) is a particular spectrally efficient form of coherent FSK.

Audio frequency-shift keying ( AFSK ) is a modulation technique by which digital data is represented by changes in the frequency ( pitch ) of an audio tone, yielding an encoded signal suitable for transmission via radio or telephone.

The first image below is the eye pattern for a binary phase-shift keying ( PSK ) system in which a one is represented by an amplitude of-1 and a zero by an amplitude of + 1.

The most fundamental digital modulation techniques are based on keying:

This technique is also referred to as color keying, colour-separation overlay ( CSO ; primarily by the BBC ), or by various terms for specific color-related variants such as green screen, and blue screen-chroma keying can be done with backgrounds of any color that are uniform and distinct, but green and blue backgrounds are more commonly used because they differ most distinctly in hue from most human skin colors.

The most common method of sending digital data over power lines at rates less than 2400 bits per second is called frequency shift keying ( FSK ).

Additionally, most vision mixers can perform keying operations and generate color signals ( called mattes in this context ).

The chroma keying technique is commonly used in video production and post-production.

This process is commonly known as " keying ", " keying out " or simply a " key ".

Thus it is commonly understood that the act of keying the carrier on and off is necessary.

Originally Gaussian frequency-shift keying ( GFSK ) modulation was the only modulation scheme available ; subsequently, since the introduction of Bluetooth 2. 0 + EDR, π / 4-DQPSK and 8DPSK modulation may also be used between compatible devices.

* In the case of PSK ( phase-shift keying ), a finite number of phases are used.

* In the case of FSK ( frequency-shift keying ), a finite number of frequencies are used.

* In the case of ASK ( amplitude-shift keying ), a finite number of amplitudes are used.

The military used frequency shift keying technology and this technology proved very reliable even over long distances.

The Milgo 4400 / 48 modem ( circa 1967 ) used vestigial sideband and phase-shift keying to provide 4800-bit / s transmission over a 1600 Hz channel.

* Crypto-production equipment: Equipment used to produce or load keying material

Most early telephone-line modems used audio frequency-shift keying to send and receive data at rates up to about 1200 bits per second.

Two common examples are " binary phase-shift keying " ( BPSK ) which uses two phases, and " quadrature phase-shift keying " ( QPSK ) which uses four phases, although any number of phases may be used.

Chroma keying is also used in the entertainment industry for special effects in movies and videogames.

Blue was used as a backdrop before digital keying became commonplace because it was necessary for the optical process, but it needed more illumination than green.

Continuous wave ( CW ) is on-and-off keying of a carrier, used only for Morse code communications.

Multiple colors can be printed by keying the paper to a frame around the woodblocks ( where a different block is used for each color ).

Binary phase-shift keying ( BPSK ) is used in the 868 and 915 MHz bands, and Offset quadrature phase-shift keying ( OQPSK ) that transmits two bits per symbol is used in the 2. 4 GHz band.