What is "digital signal"

n. A signal that only takes discrete values (contrasted to an analog signal that can take continuously varying values).

A digital signal is a signal that represents a sequence of discrete values. A logic signal is a digital signal with only two possible values, and describes an arbitrary bit stream. Other types of digital signals can represent three-valued logic or higher valued logics.

A digital signal is a physical quantity that alternates between a discrete set of waveforms. Alternatively, a digital signal may be considered to be the sequence of codes represented by such a physical quantity. The physical quantity may be a variable electric current or voltage, the intensity, phase or polarization of an optical or other electromagnetic field, acoustic pressure, the magnetization of a magnetic storage media, etcetera. Digital signals are present in all digital electronics, notably computing equipment and data transmission.

With digital signals, system noise, provided it is not too great, will not affect system operation whereas noise always degrades the operation of analog signals to some degree.

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.

The process of analog-to-digital conversion produces a digital signal. It can be thought of as two steps: (1) sampling, which produces a continuous-valued discrete-time signal, and (2) 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), 32-bit (4.3 billion levels). But the number of quantization levels is not limited to powers of two.

Digital signal may refer to:

• Digital signal (electronics), an analog signal that represents digital data
• Digital signal (signal processing), a discrete time, quantized representation of an analog signal
• The finger, an obscene gesture
• Digital data signal
• Signals in digital broadcasting
• Signals in digital electronics
• Signals in digital data transmission
• Signals in digital telephony