TERMS AND COMPONENTS
WORKING OF DIGITAL SIGNAL PROCESSOR
DIGITAL FILTERAND ITSTYPES
DIGITAL: Operating by the use of discrete signals to
represent data in the form of numbers.
SIGNAL: A variable parameter by which information is
conveyed through an electronic circuit.
PROCESSING: To perform operations on data
according to the programmed instructions.
Digital signal processing :IT can be defined as
analysis, interpretation, and manipulation of signals like
sound, images time-varying measurement values and
Converting a continuously changing
waveform (analog) into a series of discrete
The analog waveform is sliced into equal
segments and the waveform amplitude is
measured in the middle of each segment
The collection of measurements make up the
digital representation of the waveform
Three most commonly used digital modulation schemes for
Digital data over bandpass channels are:
Amplitude shift keying (ASK)
Phase shift keying (PSK)
Frequency shift keying (FSK)
When digital data is transmitted over an all digital
network a scheme known
As pulse code modulation (PCM) is used.
A microprocessor with its limited speed is
meant for low speed applications whereas
the DSP is meant for fast real time
Generally microprocessors useVan-nuemann
architecture whereas most of the DSP
processors use a modified Harvard
architecture with two or three memory
Digital filter:numerical procedure or algorithm
that transforms a given sequence of numbers
into second set of sequence that has some more
Broadly speaking ,two types of digital filters
FIR Filters(Finite impulse response filters)
IIR Filters (Infinite Impulse response filters)
FIR filter: uses only current and past input digital samples to
obtain a current output sample value. It does not utilize past
output samples. Simple FIR equation is mention below.
y(n)= h(0)x(n) + h(1)x(n-1) + h(2)x(n-2) + h(3)x(n-3) + h(4)x(n-4)
IIR filter: uses current input sample value, past input and output
samples to obtain current output sample value. Simple IIR
equation is mention below.
y(n)= b(0)x(n) + b(1)x(n-1) + b(2)x(n-2) + b(3)x(n-3) + a(1)y(n-1) +
a(2)y(n-2) + a(3)y(n-3)
An ideal filter is transmits signal under the
pass band without attenuation and
completely suppress the signal in stop band.
it have constant gain in pass band and zero
gain in the stop band.
It has linear phase response.
It must be causal .
Desired features depend on the application.
INPUT SIGNAL OUTPUT SIGNAL
Generated by sensing Having less noise
Device(microphone) or interference
Speech With reduced
redundancy for better
An analog filter is constructed using active, passive
components like resistors, capacitors and op amps
but a digital filter constitutes adder, multiplier and delay
Digital filters are software programmable, which makes
them easy to build and test.
Digital filters require only the arithmetic operations of
addition, subtraction, and multiplication.
Digital filters do not drift with temperature or humidity .
Digital filters have a superior performance-to-cost ratio.
Digital signal processing has variety of
applications in diverse fields like
In graphic equalizers sound as well as frequency
levels can varied to produce special sound effects
and compensate for the lower sensitivity of the ear .
• enhancement of edges in images
improve recognition of object (by human or
edge – a sharp transition in the image brightness,
transitions in a signal (from Fourier theory) appear as
high-frequency components which can be amplified