Analog signal

An analog signal represents information through values that vary continuously over time or another domain. Its amplitude can take any value within a range, rather than only a finite set of levels.

Amplitude: The magnitude of a varying quantity measured from its reference level. An analog signal carries information in continuously varying magnitude.
Continuous function: A function whose output changes without jumps as its input changes. Continuity captures the defining mathematical character of analog variation.
Microphone: A transducer that converts sound waves into an electrical signal. Many microphones produce an analog voltage that follows sound pressure.
Sampling: The process of measuring a signal at discrete points in time or space. Sampling turns a continuous-time signal into a sequence of measurements.
Thermal noise: Random electrical noise caused by the thermal motion of charge carriers. It adds fluctuations to analog signals even in otherwise functioning circuits.
Frequency: The number of cycles of a periodic phenomenon occurring per unit time. Some analog signals encode information in changes to their cycle rate.
Independent variable: A variable whose value determines the input to a function or model. An analog signal varies over a domain such as time or position.
Photodiode: A semiconductor device that converts incident light into electrical current. Its output current can vary continuously with received light intensity.
Quantization: The mapping of a range of values to a finite set of discrete levels. Quantization removes the continuous amplitude range during digitization.
Generation loss: Degradation introduced when information is copied or reproduced repeatedly. Analog copies accumulate noise and distortion with each generation.

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