Quantization (signal processing)

Quantization maps a signal’s measured values to a finite set of discrete levels. It is a central step in converting continuous-valued measurements into digital representations.

Quantization step size: The spacing between adjacent reconstruction levels in a uniform quantizer. It sets the resolution and bounds the rounding error for uniformly spaced levels.
Quantization noise: The signal-like error introduced when continuous or finely valued samples are represented by discrete levels. Under suitable assumptions, quantization error is modeled as noise in signal analysis.
Analog-to-digital converter: An electronic system that converts an analog input into a digital representation. Its conversion process quantizes sampled input amplitudes into code values.
Sampling (signal processing): The process of measuring a continuous-time signal at discrete time instants. Sampling discretizes time, whereas quantization discretizes measured amplitude values.
Quantization error: The difference between an input value and its quantized representation. This error is the direct cost of replacing a range of values with discrete levels.
Signal-to-quantization-noise ratio: The ratio of signal power to quantization-noise power, usually expressed in decibels. It measures how quantization noise compares with the signal being represented.
Pulse-code modulation: A method of representing sampled signals by quantizing each sample and encoding it as a binary word. Quantization supplies the discrete amplitude values that PCM encodes.
Scalar quantization: Quantization that assigns each input value independently to a reconstruction level. It provides the point-by-point alternative to joint vector quantization.
Uniform quantization: Quantization in which adjacent levels are equally spaced. Equal spacing is the simplest rule for assigning signal values to levels.
Overload distortion: Distortion caused when an input exceeds a system’s representable range. Finite quantizer range can clip values beyond its outer decision thresholds.

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