An analog or analogue signal is any continuously variable signal. It differs from a digital signal in that small fluctuations in the signal are meaningful. Analog is usually thought of in an electrical context, however mechanical, pneumatic, hydraulic, and other systems may also use analog signals. In mathematics, a continuous function is one in which arbitrarily small changes in the input produce arbitrarily small changes in the output. ... Digital Signal represents more than one meaning. ... Electricity is a property of certain subatomic particles (e. ...

The word "analog" implies an analogy between cause and effect, voltage in and voltage out, current in and current out, sound in and frequency out. An analogy is a comparison between two different things, in order to highlight some form of similarity. ...

An analog signal uses some property of the medium to convey the signal's information. For example, an aneroid barometer uses rotary position as the signal to convey pressure information. Electrically, the property most commonly used is voltage followed closely by frequency, current, and charge. Schematic drawing of a simple mercury barometer with vertical mercury column and reservoir at base A barometer is an instrument used to measure atmospheric pressure. ... In the physical sciences, potential difference is the difference in potential between two points in a conservative vector field. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ... Electric charge is a fundamental FATTY STASHEconserved property of some subatomic particles, which determines their electromagnetic interactions. ...

Any information may be conveyed by an analog signal, often such a signal is a measured response to changes in physical phenomena, such as sound, light, temperature, position, or pressure, and is achieved using a transducer. A response is the following: Often a response is the result of a stimulus. ... A schematic representation of auditory signaling Sound is vibration, as perceived by the sense of hearing. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye, or in a more general sense, any electromagnetic radiation in the range from infrared to ultraviolet. ... Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... The word position can have one of several meanings: 2-dimensional or 3-dimensional location; Occupation, Job In finance, a position means entitlement to receive or obligation to deliver an asset or financial instrument, as in long position (ownership) and short position (obligation to deliver); In politics and government a... Pressure is the application of force to a surface, and the concentration of that force in a given area. ... A transducer is a device that converts one type of energy to another, or responds to a physical parameter. ...

For example, in an analog sound recording, the variation in pressure of a sound striking a microphone creates a corresponding variation in the current passing through it. An increase in the volume of the sound causes the fluctuation of the current to increase while keeping the same rhythm. Pressure is the application of force to a surface, and the concentration of that force in a given area. ... A schematic representation of auditory signaling Sound is vibration, as perceived by the sense of hearing. ... A microphone with a cord A microphone, sometimes called a mic (pronounced mike), is a device that converts sound into an electrical signal. ...

The primary disadvantage of analog signalling is that any system has noise—that is, random variations—in it. As the signal is copied and re-copied, or transmitted over long distances, these random variations become dominant. Electrically these losses are lessened by shielding, good connections, and several cable types such as coax and twisted pair. In science, and especially in physics and telecommunication, noise is fluctuations in and the addition of external factors to the stream of target information (signal) being received at a detector. ...

The effects of noise make signal loss and distortion impossible to recover, since amplifying the signal to recover attenuated parts of the signal amplifies the noise as well. In general usage, noise can be considered data without meaning; that is, data that is not being used to transmit a signal, but is simply produced as an unwanted by-product of other activities. ...

Another method of conveying an analog signal is to use modulation. In this, some base signal (e.g., a sinusoidal carrier wave) has one of its properties altered: amplitude modulation involves altering the amplitude of a sinusoidal voltage waveform by the source information, frequency modulation changes the frequency. Other techniques, such as changing the phase of the base signal also work. Modulation is the process of varying a carrier signal, typically a sinusoidal signal, in order to use that signal to convey information. ... In mathematics, the trigonometric functions are functions of an angle, important when studying triangles and modeling periodic phenomena. ... A carrier wave is a waveform (usually sinusoidal) that is modulated (modified) to represent the information to be transmitted. ... Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. ... A wave crashing against the shore A wave is a disturbance that propagates. ... Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Phase, from the Greek phasis, meaning appearance, has a number of related meanings in English. ...

Analog circuits do not involve quantisation of information into digital format. The concept being measured over the circuit, whether sound, light, pressure, temperature, or an exceeded limit, remains from end to end. Generally, quantization is the state of being constrained to a set of discrete values, rather than varying continuously. ...

Clocks with hands are called analog; those that display digits are called digital. However, many analog clocks are actually digital since the hands do not move in a smooth continuous motion, but in small steps every second or half a second. A clock (from the Latin cloca, bell) is an instrument for measuring time. ...

See digital for a discussion of digital vs. analog. A digital system is one that uses discrete values rather than a continuous spectrum of values: compare analog. ...

Sources: Some of an earlier version of this article was originally taken from Federal Standard 1037C in support of MIL-STD-188. Federal Standard 1037C entitled Telecommunications: Glossary of Telecommunication Terms is a U.S. Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ... MIL-STD-188 is a series of U.S. military standards relating to telecommunications. ...

See also

• Analog computer
• Analog to digital converter
• Digital to analog converter
• Analog television
• Analog synthesizer
• Analog photocopier