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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: 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.
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 ...
In digital audio using pulse-code modulation (PCM), bit depth is the number of bits of information in each sample, and it directly corresponds to the resolution of each sample. Examples of bit depth include Compact Disc Digital Audio , which uses 16 bits per sample, and DVD-Audio and Blu-ray Disc , which can support up to 24 bits per sample.
If the sequence of divide by N and divide by (N + 1) is periodic, spurious signals appear at the VCO output in addition to the desired frequency. Delta-sigma fractional-n dividers overcome this problem by randomizing the selection of N and (N + 1) while maintaining the time-averaged ratios.
This results in a broadband dynamic range of only 7.78 dB, but it is not consistent among frequency bands, and in the lowest frequencies (the audible range) the dynamic range is much greater — over 100 dB. Noise shaping is inherently built into the delta-sigma modulators. The 1-bit converter is the basis of the DSD format by Sony.
Delta-Sigma modulation is a more advanced variant of Delta modulation which allows for high-fidelity encodings for low-amplitude signals. This is done through quantizing at a high oversampling rate, allowing for a precise encoding of slight changes in the audio signal. Delta-sigma modulation is used in situations where maintaining a high audio ...
Some modulation schemes, such as frequency modulation, survive the nonlinear distortion without ill effect (but schemes such as amplitude modulation do not). Frequency multiplication is also used in nonlinear optics. The nonlinear distortion in crystals can be used to generate harmonics of laser light.