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Anna university
**Course:
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B.Tech
**Specialization:
**Electronics and Communication Engineering**Offline Downloads:
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FATIMA MICHAEL COLLEGE OF ENGINEERING & TECHNOLOGY
Senkottai Village, Madurai – Sivagangai Main Road,
Madurai -625 020
An ISO 9001:2008 Certified Institution
IT6502-DIGITAL SIGNAL PROCESSING
SEMESTER : 6
YEAR
:III
BRANCH
: CSE
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UNIT I SIGNALS AND SYSTEMS
Signal:
Signal is a function of one or more independent variables which contain
some information.
System: A system is a set of elements or functional block that are connected
together and produces an output in response to an input signal.
Processing:
Operations performed by the system on the signal is called
processing.
Types of signal processing:
1.Analog signal processing.
2.Digital signal processing.
In this processing input signal,output signal and the
Analog signal processing:
system are all analog in nature.
Digital signal processing:
Dsp is the processing of signals by digital
systems.Input and output signals are also digital in nature.
Basic elements of Digital signal processing:
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ADC:
It converts analog input to digital input.
Digital Signal processor:
It performs amplification,attenuation,filtering,spectral analysis,feature
extraction etc operations on digital data.
DAC:
Some of the processed signals are required back in the analog form.So we
use DAC to convert digital output to its analog equivalent.
Advant ages of Dsp over Anlog signal processing:
1.Flexibility.
2.Accuracy.
3.Easy storage.
4.Mathematical processing.
5.Cost.
Applications:
1.Speech processing.
2.Telecommunication.
3.Biomedical Engineering.
4.Instrumentation
Types of signals based on time:
1.Continuous time signals.
2.Discrete time signals.
Continuous time signals:
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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
measurement signals.
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:
x(n)=x0 (nTs)
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