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Digital Signal Processing
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Copyright © 2005. Shi Ping CUC
Shi Ping
School of Information Engineering
CUC
Digital Signal Processing
Copyright © 2005. Shi Ping CUC
Text books :《数字信号处理教程 》 (第三版)清华大学出版社,程佩青 2006 年
Course outline
Reference books : <Digital Signal Processing Using MATLAB>英文影印版 科学出版社Vinay K. Ingle John G. Proakis 2003
Copyright © 2005. Shi Ping CUC
Reference books : 王世一 《数字信号处理》北京理工大学出版社 ,1997年 A.V.奥本海姆 R.W.谢弗 J.R.巴克 编著 刘树堂 黄建国 译《离散时间信号处理》(第 2版)西安交通大学出版社 2001年 胡广书《数字信号处理-理论、算法与实现》(第二版)清华大学出版社 2003年
Course outline
Copyright © 2005. Shi Ping CUC
Relationship with other courses
About MATLAB Software
Requirements
Course outline
Copyright © 2005. Shi Ping CUC
Chapter 1 Introduction to DSP
Content
Signal, System, Signal Processing
The Constitution of DSP System
How to implement the DSP
The Application of DSP
The advantages of DSP
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
Signal
A signal is a function of independent variables such as time, distance, position, temperature and pressure
Depending on the nature of the independent variables and the value of the function, we can classify the signals as follows
Signals play an important role in our daily life.Most signals we encounter are generated naturally. However, a signal can also be generated synthetically or by a computer.
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
● scalar signal A signal generated by a single source
● vector signal (or multichannel signal) A signal generated by multiple sources
● one dimensional (1-D) signal A function of a single independent variable
● multidimensional (M-D) signal A function of more than one independent variables
sound Image Video
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
● continuous-time signal The independent variable is continuous ● discrete-time signal (sequence) The independent variable is discrete● analog signal A continuous-time signal with a continuous amplitude● quantized-boxcar signal A continuous-time signal with a discrete-value amplitude● digital signal A discrete-time signal with a discrete-value amplitude● Sampled-data signal A discrete-time signal with a continuous amplitude
see
)(nx
)(tx
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
● deterministic signal A signal that can be uniquely determined by a
well-defined process, such as a mathematical expression or rule, or table look-up.
● random signal A single that is generated in a random fashion
and cannot be predicted ahead of time.
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
● periodic signal A signal that repeats itself in a periodic fashion from
negative to positive infinity.
● aperiodic signal A signal that extends to both positive and negative
infinity without repeating in a periodic pattern.
)()()()(
kNnxnxkTtxtx
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
● energy signal An finite energy signal with zero average power.
● power signal An infinite energy signal with finite average power.
22 )()( nxEdttxE
1
0
2
0
2 )(1lim)(1limN
nN
T
Tnx
NPdttx
TP
a periodic sequence — power signala finite-length sequence — energy signal
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
SystemA system is any process that produces an output signal in response to an input signal.
Depending on the types of the signal processed, we can classify the systems as follows:
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
● analog system input and output analog signals
● digital system input and output digital signals
● continuous-time system input and output continuous-time signals
● discrete-time system input and output discrete-time signals
Copyright © 2005. Shi Ping CUC
Signal, System, Signal Processing
Signal Processing
A signal carries information !
The objective of signal processing:To extract, enhance, store and transmit the useful information carried by the signal.
Digital signal processing:To implement the signal processing by a digital means.
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Copyright © 2005. Shi Ping CUC
The Constitution of DSP System
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waveform
ADC DACDSPPrF PoFanalog analog
Equivalent to an analog signal processor
PrF: antialiasing filtering PoF: smooth out the staircase waveform
example
Copyright © 2005. Shi Ping CUC
How to Implement the DSP
To handle the DSP algorithms in a general-purpose microprocessor by means of software programming
To handle the DSP algorithms in a specifically designed Digital Signal Processors (DSPs)
return
Copyright © 2005. Shi Ping CUC
The Application of DSP
Signal Analysis Measurement of signal properties Spectrum (frequency/phase) analysis Target detection, verification, recognition
Signal Filtering Signal-in-signal-out, filter Removal of noise/interference Separation of frequency bands
The main tasks of DSP
Copyright © 2005. Shi Ping CUC
The Application of DSP
DSP application examples
Telecommunications Multiplexing Compression Echo control
Audio Processing Music Speech generation Speech recognition
Copyright © 2005. Shi Ping CUC
The Application of DSP
DSP application examples
Echo Location Radar Sonar Reflection seismology
Image Processing Medical Space Commercial Imaging Products
Copyright © 2005. Shi Ping CUC
The Application of DSP
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Demonstration
bellclarinet brass
FM synthesis of sound
chirp
Digital image processing
Deblurring
Noise reduction
Edge detection
Copyright © 2005. Shi Ping CUC
The Advantages of DSP
Absence of drift in the filter characteristics Improved quality level Reproducibility Ease of new function development Multiplexing Modularity Total single chip implementation using VLSI technology
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Copyright © 2005. Shi Ping CUCreturn
The sound signal is an example of a 1-D signal where the independent variable is time
Copyright © 2005. Shi Ping CUC
A black-and-white image signal is an example of a 2-D signal where the 2 independent variables are the 2 spatial variables.
),( yxI
Copyright © 2005. Shi Ping CUCreturn
A color image signal is a 3-channel signal composed of three 2-D signals representing the three primary color: red, green and blue (RGB)
),(),(),(
),(yxIyxIyxI
yxu
G
G
R
Copyright © 2005. Shi Ping CUC
A black-and-white video signal is an example of a 3-D signal where the 3 independent variables are the 2 spatial variables and the time variable.
),,( tyxI
Copyright © 2005. Shi Ping CUCreturn
A color video signal is a 3-channel signal composed of three 3-D signals representing the three primary color: red, green and blue (RGB)
),,(),,(),,(
),,(tyxItyxItyxI
tyxu
B
G
R
Copyright © 2005. Shi Ping CUC
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