Digital signal processing
presentation on digital signal processing
Aug 17, 2015
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Digital signal processing
CONTENTS
INTRODUCTION
TERMS AND COMPONENTS
WORKING OF DIGITAL SIGNAL PROCESSOR
COMPARISION WITH MICROPROCESSORS
DIGITAL FILTER AND ITS TYPES
APPLICATIONS
Terms of signal processing
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 sensor data
What is DSP?
Converting a continuously changing waveform (analog) into a series of discrete levels (digital)
What is DSP?
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
What is DSP?
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21 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37
How Does It Work?
A waveform is sliced up and converted it into digital form
Draw a simple waveform on graph paper Scale appropriately
“Gather” digital data points to represent the waveform
Starting Waveform Used to Create Digital Data
Waveform Created from Digital Data
How Does It Work?
Compare the original with the recreating, note similarities and differences
Noise Filtering Using Averaging
NOISE FILTERING
Three most commonly used digital modulation schemes for transmitting
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.
Digital modulation techniques
DIFFERENCE BETWEEN MICROPROCESSOR AND DIGITAL SIGNAL PROCESSOR
A microprocessor with its limited speed is meant for low speed applications whereas the DSP is meant for fast real time applications.
Generally microprocessors use Van-nuemann architecture whereas most of the DSP processors use a modified Harvard architecture with two or three memory buses.
VARIOUS DSP PROCESSORSTexas DSP Processors
16-bit Fixed point arithmetic processors TMS320C1X TMS320C2X TMS320C5X TMS320C8X
32-bit floating point arithmetic processors
TMS320C3X TMS320C4X
WHAT IS DIGITAL FILTER
Digital filter:numerical procedure or algorithm that transforms a given sequence of numbers into second set of sequence that has some more desirable properties.
DIGITAL FILTER
INPUT SEQUENCEOutput sequence
TYPES OF DIGITAL FILTER
Broadly speaking ,two types of digital filters exists.
FIR Filters(Finite impulse response filters)
IIR Filters (Infinite Impulse response filters)
FINITE IMPULSE RESPONSE FILTER
INFINITE IMPULSE RESPONSE FILTER
DIFFERENCE BETWEEN FIR AND IIR FILTER
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)
WHAT IS IDEAL FILTER?
An ideal filter is transmits signal under the pass band without attenuation and completely suppress the signal in stop band.
Characteristics – 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
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 efficiency of transmission
ADVANTAGES OF DIGITAL FILTER OVER ANALOG
An analog filter is constructed using active, passive components like resistors, capacitors and op ampsbut a digital filter constitutes adder, multiplier and delay elements.
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.
APPLICATIONS OF DSP
Digital signal processing has variety of applications in diverse fields like
Digital filteringSpectral analysisSpeech processing Image processingRadar processing
Robot controlTelecommunicationConsumer electronicsBiomedical engineeringMilitary applications
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 imagesimprove recognition of object (by human or
computer)edge – a sharp transition in the image brightness,
sharptransitions in a signal (from Fourier theory) appear
ashigh-frequency components which can be amplified
THANK YOU
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