The result of the conversion of the original (analog) video signal into a pattern of bits. A digital signal has a discrete value at each sampling point, and its precision is a factor of how many samples get converted per unit of time.

In the context of digital signal processing (DSP), a digital signal is a discrete-time signal for which not only the time but also the amplitude has discrete values; in other words, its samples take on only values from a discrete set (a countable set that can be mapped one-to-one to a subset of integers). If that discrete set is finite, the discrete values can be represented with digital words of a finite width. Most commonly, these discrete values are represented as fixed-point words (either proportional to the waveform values or companded) or floating-point words.

Discrete cosine waveform with frequency of 50 Hz and a sampling rate of 1000 samples/sec, easily satisfying the sampling theorem for reconstruction of the original cosine function from samples

The process of analog-to-digital conversion produces a digital signal. The conversion process can be thought of as occurring in two steps:

sampling, which produces a continuous-valued discrete-time signal, and

quantization, which replaces each sample value by an approximation selected from a given discrete set (for example by truncating or rounding).

It can be shown that for signal frequencies strictly below the Nyquist limit that the original continuous-valued continuous-time signal can be almost perfectly reconstructed, down to the (often very low) limit set by the quantisation.

Common practical digital signals are represented as 8-bit (256 levels), 16-bit (65,536 levels), 24-bit (16.8 million levels) and 32-bit (4.3 billion levels). But the number of quantization levels is not necessarily limited to powers of two. A floating point representation is used in many DSP applications.

amplitude

context digital signal processing

digital signal

discrete set

discrete time signal

discrete values

dsp

levels

time

words

context digital signal processing

digital signal

discrete set

discrete time signal

discrete values

dsp

levels

time

words

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