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Delta-sigma (ΔΣ; or sigma-delta, ΣΔ) modulation is an oversampling method for encoding signals into low bit depth digital signals at a very high sample-frequency as part of the process of delta-sigma analog-to-digital converters (ADCs) and digital-to-analog converters (DACs).
English: Simple circuit performing delta-sigma modulation on an input 20 kHz sine wave s(t). An ideal op amp integrator using s(t) and p(t) produces ε(t), which can be quantized and sampled by an ideal D flip flop to produce a pulse density modulation result p(t), which used as negative feedback.
English: Delta-sigma modulation loop model with quantization noise in the Laplace (s) domain. Integration become 1/s, and the quantization process can be modeled as simply adding noise. Integration become 1/s, and the quantization process can be modeled as simply adding noise.
The Whittaker–Shannon interpolation formula is mathematically equivalent to an ideal low-pass filter whose input is a sequence of Dirac delta functions that are modulated (multiplied) by the sample values. When the time interval between adjacent samples is a constant (), the sequence of delta functions is called a Dirac comb.
Delta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance. DM is the simplest form of differential pulse-code modulation (DPCM) where the difference between successive samples is encoded into n-bit data ...
English: This is a block diagram of a simplified Delta Sigma ADC and is my own work drawn using "Inkscape" a free svg editor. It was drawn to illustrate a description of the functioning of the so-called Delta Sigma ADC which appears in the overall article on Delta Sigma modulation.
Oversampling DACs or interpolating DACs such as those employing delta-sigma modulation, use a pulse density conversion technique with oversampling. Audio delta-sigma DACs are sold with 384 kHz sampling rate and quoted 24-bit resolution, though quality is lower due to inherent noise (see § Figures of merit).
The amplitude is the only information explicitly stored in the sample, and it is typically stored as either an integer or a floating-point number, encoded as a binary number with a fixed number of digits – the sample's bit depth, also referred to as word length or word size.