Signal

signalselectrical signalelectrical signalssignal boxsignalingelectric signalelectronic signalsinput signalmodulated electric currentsignalling
In communication systems, signal processing, and electrical engineering, a signal is a function that "conveys information about the behavior or attributes of some phenomenon".wikipedia
542 Related Articles

Signal processing

signal analysissignalsignal processor
In communication systems, signal processing, and electrical engineering, a signal is a function that "conveys information about the behavior or attributes of some phenomenon".
Signal processing is a subfield of mathematics, information and electrical engineering that concerns the analysis, synthesis, and modification of signals, which are broadly defined as functions conveying "information about the behavior or attributes of some phenomenon", such as sound, images, and biological measurements.

Information

informativeinputinputs
In communication systems, signal processing, and electrical engineering, a signal is a function that "conveys information about the behavior or attributes of some phenomenon".
Information can be encoded into various forms for transmission and interpretation (for example, information may be encoded into a sequence of signs, or transmitted via a signal).

Transducer

transducerstransductiontransduce
In human engineering, signals are typically provided by a sensor, and often the original form of a signal is converted to another form of energy using a transducer.
Usually a transducer converts a signal in one form of energy to a signal in another.

Microphone

microphonescondenser microphonedynamic microphone
For example, a microphone converts an acoustic signal to a voltage waveform, and a speaker does the reverse. Sound. Since a sound is a vibration of a medium (such as air), a sound signal associates a pressure value to every value of time and three space coordinates. A sound signal is converted to an electrical signal by a microphone, generating a voltage signal as an analog of the sound signal, making the sound signal available for further signal processing. Sound signals can be sampled at a discrete set of time points; for example, compact discs (CDs) contain discrete signals representing sound, recorded at 44,100 samples per second; each sample contains data for a left and right channel, which may be considered to be a 2-vector signal (since CDs are recorded in stereo). The CD encoding is converted to an electrical signal by reading the information with a laser, converting the sound signal to an optical signal.
A microphone, colloquially nicknamed mic or mike, is a transducer that converts sound into an electrical signal.

Signal integrity

signal qualityhigh-speed data linkshigh-speed digital
The prevention of noise is covered in part under the heading of signal integrity.
Signal integrity or SI is a set of measures of the quality of an electrical signal.

Crosstalk

cross-talkcross talkleakage
The term noise usually means an undesirable random disturbance, but is often extended to include unwanted signals conflicting with the desired signal (such as crosstalk).
In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel.

Detection theory

signal detection theorysignal detectionsignal recovery
The separation of desired signals from a background is the field of signal recovery, one branch of which is estimation theory, a probabilistic approach to suppressing random disturbances.
Detection theory or signal detection theory is a means to measure the ability to differentiate between information-bearing patterns (called stimulus in living organisms, signal in machines) and random patterns that distract from the information (called noise, consisting of background stimuli and random activity of the detection machine and of the nervous system of the operator).

Estimation theory

parameter estimationestimationestimated
The separation of desired signals from a background is the field of signal recovery, one branch of which is estimation theory, a probabilistic approach to suppressing random disturbances.
As another example, in electrical communication theory, the measurements which contain information regarding the parameters of interest are often associated with a noisy signal.

Data transmission

digital communicationsdata transferdata communication
Engineering disciplines such as electrical engineering have led the way in the design, study, and implementation of systems involving transmission, storage, and manipulation of information.
The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal.

Signaling (telecommunications)

signalsignalingsignalling
In telephone networks, signaling, for example common-channel signaling, refers to phone number and other digital control information rather than the actual voice signal.
In telecommunication, signaling is the use of signals for controlling communications.

Telephone

phonetelephonesLocal Telephone Service
For example, the words "Mary had a little lamb" might be the message spoken into a telephone.
The transmitter converts the sound waves to electrical signals which are sent through a telephone network to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker.

Communications system

communication systemcommunication systemstelecommunications system
In communication systems, signal processing, and electrical engineering, a signal is a function that "conveys information about the behavior or attributes of some phenomenon".
Equipment consists of a transmitter, which encodes a message into an optical signal, a communication channel, which carries the signal to its destination, and a receiver, which reproduces the message from the received optical signal.

Information content

self-informationsurprisalinformation
Another important property of a signal is its entropy or information content.
In information theory, information content, self-information, or surprisal of a random variable or signal is the amount of information gained when it is sampled.

Electrical engineering

electrical engineerelectricalelectrical engineers
In communication systems, signal processing, and electrical engineering, a signal is a function that "conveys information about the behavior or attributes of some phenomenon".
Signal processing deals with the analysis and manipulation of signals.

Digital signal

digitaldigital signalsbinary signal
Two main types of signals encountered in practice are analog and digital.
A digital signal is a signal (in electronic devices a voltage or a current) that is being used to represent data as a sequence of discrete values; at any given time it can only take on one of a finite number of values.

Electronic engineering

electronics engineeringelectronic engineerelectronics engineer
In the latter half of the 20th century, electrical engineering itself separated into several disciplines, specialising in the design and analysis of systems that manipulate physical signals; electronic engineering and computer engineering as examples; while design engineering developed to deal with functional design of user–machine interfaces.
Signal processing deals with the analysis and manipulation of signals.

Discrete time and continuous time

discrete-timediscrete timecontinuous-time
Discrete-time signals are often referred to as time series in other fields.
A continuous signal or a continuous-time signal is a varying quantity (a signal)

Information theory

information theoristinformation-theoreticinformation
The formal study of the information content of signals is the field of information theory.
Under these constraints, we would like to maximize the rate of information, or the signal, we can communicate over the channel.

Analog signal

analoganalogueanalogue signal
Two main types of signals encountered in practice are analog and digital.
The term analog signal usually refers to electrical signals; however, mechanical, pneumatic, hydraulic, human speech, and other systems may also convey or be considered analog signals.

Magnetic storage

magnetic recordingmagnetic mediamagnetic disk
The physical quantity may be a variable electric current or voltage, the intensity, phase or polarization of an optical or other electromagnetic field, acoustic pressure, the magnetization of a magnetic storage media, etcetera.
Poulsen's device recorded a signal on a wire wrapped around a drum.

Stereophonic sound

Stereostereophonicstereo sound
Sound. Since a sound is a vibration of a medium (such as air), a sound signal associates a pressure value to every value of time and three space coordinates. A sound signal is converted to an electrical signal by a microphone, generating a voltage signal as an analog of the sound signal, making the sound signal available for further signal processing. Sound signals can be sampled at a discrete set of time points; for example, compact discs (CDs) contain discrete signals representing sound, recorded at 44,100 samples per second; each sample contains data for a left and right channel, which may be considered to be a 2-vector signal (since CDs are recorded in stereo). The CD encoding is converted to an electrical signal by reading the information with a laser, converting the sound signal to an optical signal.
The two signals were sent out over separate AM station bands.

Amplifier

amplifiersamplificationamplified
Once expressed as an electronic signal, the signal is available for further processing by electrical devices such as electronic amplifiers and electronic filters, and can be transmitted to a remote location by electronic transmitters and received using electronic receivers.
An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power of a signal (a time-varying voltage or current).

Frequency

frequenciesperiodperiodic
In an electrical signal, the voltage, current, or frequency of the signal may be varied to represent the information.
This is an electronic instrument which measures the frequency of an applied repetitive electronic signal and displays the result in hertz on a digital display.

Current loop

4-20 mA4-20mA4–20 mA
Current loop – a signaling system in widespread use for process control
In electrical signalling an analog current loop is used where a device must be monitored or controlled remotely over a pair of conductors.

Noise (electronics)

noiseelectronic noiseelectrical noise
The information in a signal is usually accompanied by noise.
In communication systems, noise is an error or undesired random disturbance of a useful information signal.