What is Digital signal?
'''Digital signal''' can mean two different things: # ''discrete-time signals'' that are digitized. # the [[waveform]] signals in a [[digital]] system. ==Discrete-time signals == {{main|Signal (electrical engineering)}} '''Digital signals''' are digital representations of ''discrete-time signals'', which are often produced by changing an [[analog signal]]. An [[analog signal]] is a datum that changes over time (for instance the [[temperature]] at a given place; the depth of a certain point in a pond; or the [[amplitude]] of the [[voltage]] at some [[node]] in a [[Electrical circuit|circuit]]). A discrete-time signal is a sampled version of an analog signal: the value of the datum is noted at fixed intervals (for example, every microsecond) rather than continuously. In short, a digital signal is a quantized discrete-time signal; a discrete-time signal is a sampled analog signal. In the [[digital revolution]] the usage of digital signals has increased significantly. Many modern media devices, especially the ones that connect with computers use digital signals to represent signals that were traditionally represented as analog signals; cell phones, music and video players, personal video recorders, and digital cameras are examples. In most applications, digital signals are represented as [[binary number]]<nowiki/>s, so their precision of quantization is measured in [[bit]]s. ==Waveforms in digital systems== [[Image:S_digital.PNG|framed|Digital signal: 1) Low level, 2) High level, 3) Rising edge, and 4) Falling edge.]] {{main|Digital}} In [[computer architecture]] and other [[digital]] systems, a [[waveform]] that switches between two voltage levels representing the two states of a [[Boolean algebra|Boolean]] value (0 and 1) is referred to as a '''digital signal.''' The [[clock signal]] is a special digital signal that is used to [[synchronization|synchronize]] digital circuits. The image shown can be considered the waveform of a clock signal. Logic changes are triggered either by the rising edge or the