Continuous time or analog signals are signals that are
defined for every value of a < t < b, where (a, b) can be ( -¥, + ¥ ), i.e., x (t) = e-|t|
or x(t) = cos(pt). .
Frequency concept in continuous time signal:
Discrete time signal:
Discrete-time signals are defined at discrete-time instants and between
the two discrete time instants are undefined but are not zero. They can be obtained
either by sampling analog signals or they can be discrete in nature like discrete
A discrete-time signal having a set of discrete values is called a digital
signal. Note that sampling an analog signal produces a discrete-time signal. Then
quantization of its values produces a digital signal.
Thus, the sequence values x(0) to x(N - 1) may often be considered to be the
elements of a column vector as follows:
Discrete-time signals are often derived by sampling a c ontinuous-time signal, such
as speech, with an analogto-digital (A/D) converter) For example, a continuoustime signal x,(t) that is sampled at a rate of fs = l/Ts samples per second produces
the sampled signal x(n), which is related to xa(t) as follows: