Properties & Classification Of Signals


This includes the basic signals, their properties & classification of signals based on these properties. To easily understand signals & systems, we would visualize signals as simple mathematical functions.

Continuous & Discrete Signals

Continuous signals & those defined over a set of real numbers(R) & discrete signals & those defined for discrete integers(I).
For instance, a signal(a function) having the domain [0,10] is continuous & one having the domain {1,2,3…10} is discrete.

A Continuous Signal can be converted to a Discrete Signal using an Analog-to-Digital Converter(ADC). The conversion consists of a process called sampling.

The sampling process simply samples out values of the signal at certain points seperated by an equal interval called the sampling period. signals_sampling In the above figure, the sampling period would be 3.

compact_disc A common application of the above process is a Compact Disc(CD) which is simply a signal sampled at 44.1kHz & Quantized at 16 bits/2 bytes.

Analog & Digital Signals Analog Signals are continuous electric signals which arise from non-electric signals. The variable of the converted signal is analogous to the non-electric time varying signal & hence, they are called analog signals. A good example is an audio(speech) signal.

A digital signal, unlike the analog signal, takes only two vales-HIGH or LOW, ON or OFF, 0 or 1, TRUE or FALSE, etc. All computers & other gadgets use digital signals to store information. (The term sometimes also refers to discrete time signals which can also take discrete values other than 0’s & 1’s)


Based on the above, we may infer that a analog signal is continuous signal & a digital signal is a discrete time signal.

Signals are also classified as… causal_signal

We then have Deterministic & Random Signals.

A random signal takes random values & at a point on the signal, we cannot determine its value just before it or just after it. However, these values can be easily determined for a deterministic signal. deterministic_signals Next Post in this Category >> Signal Operations



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