数字信号处理双语版ppt第一章

Understanding DSP, Second Edition
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1.1.1 Discrete-time Signals - Most DT signal are obtained by sampling continuous-time signals.
Understanding DSP, Second Edition
reconstructed based on xa(nT).
Understanding DSP, Second Edition
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1.1.1 Discrete-time Signals
About Sequence:
{x(n)} is a real sequence if x(n) is real for any n.
Understanding DSP, Second Edition
参考书:
1. 数字信号处理教程(第二版）
程佩青
清华大学出版社
2. 数字信号处理
丁玉美
西安电子科技大学出版社
Understanding DSP, Second Edition
3. S. K. Mitra, Digital signal processing
– a computer-based approach, second edition, Copyright 2001 by McGraw-Hill Comp
Understanding DSP, Second Edition
What is a Signal ? • ������ In mathematics: a function of independent variable(s) (the variation of a quantity)
The length of a finite length sequence is:
N= N2-N1+1: N point sequence
Understanding DSP, Second Edition
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1.1.1 Discrete-time Signals
About Sequence:
x(n) is a infinite len源自文库th sequence if it is defined for infinite time interval.
• ������
In physics: a means to convey information
(a mapping that map the information to the signal that carries the information)
Understanding DSP, Second Edition
Digital Signal Processing
Understanding DSP, Second Edition
教材：
《数字信号处理（第二版（英文版）》 作译者：张建华
电子工业出版社 , • 在Richard G.Lyons所著 Understanding Digital Signal Processing， Second Edition的基础上进行了改编
-
Understanding DSP, Second Edition
Understanding DSP, Second Edition
1.1.1 Discrete-time Signals
• Discrete-Time(DT) Signals:
- Defined at discrete time instants.
1.1.1 Discrete-time Signals
x(n)
comes from:
xa(t)=sin(2πft) Uniformed sampled as: xa(nT)=sin(2πfnT) T denotes sampling interval or period and its reciprocal is sampling frequency written as: sampling frequency
(Continuous –Discrete)
–Analog, Sampled, Quantized, Digital
Understanding DSP, Second Edition
������
• Determinateness
(Deterministic–Random) Time-invariant, Time-variant Linear models, Non-linear model Prior knowledge, Unpredictable
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Understanding DSP, Second Edition
1.1.1 Discrete-time Signals
Relationship between xa(nT) and xa(t): Part and whole; Under certain conditions, xa(t) can be exclusively
(By appending with zeros or zero-padding, finite length sequence ������ infinite.)
- A discrete-time signal is represented as a sequence of numbers called samples and can be mathematically denoted as such a set
{x(n)} , - n
Understanding DSP, Second Edition
1.1.1 Discrete-time Signals
{x(n)}: n: index, integer in the range -∞ and +∞,
x(n) is one sample
E.g.
• • • • •
x(-1)=-0.1564; x(0)=0; x(1)=0.1564; x(2)=0.3090; …
Understanding DSP, Second Edition
What is Digital Signal Processing?
• ������
The world of science and engineering is filled with signals: images from remote space probes, voltages generated by the heart and brain, radar and sonar echoes, seismic vibrations, and countless other applications.
1.9 The Stability Property of Linear Time-Invariant Systems
1.10 Analyzing Linear Time-Invariant Systems
Understanding DSP, Second Edition
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1.1.1 Discrete-time Signals
Classification of Signals • ������ Type of Value
–Real-valued, Complex-valued • ������ Dimension
–Scalar, Vector –One Dimensional, Multi-Dimensional • ������ Representation of Value
• ������ Digital Signal Processing is the science of using computers to understand these types of data. • ������ This includes a wide variety of goals: filtering, speech recognition, image enhancement, data compression, neural networks, and much more. DSP is one of the most powerful technologies that will shape science and engineering in the twenty-first century.
• Continuous-Time (CT) signals:
-
All CT signals are thought of as a pattern of variations in time and represented as a time function x(t).
defined at every time instant.
• Make DSP an integral part of any E.E. curriculum
Understanding DSP, Second Edition
• Learning digital signal processing is not something you accomplish; it’s a journey you take. When you gain an understanding of some topic, questions arise that cause you to investigate some other facet of digital signal processing. Armed with more knowledge, you’re likely to begin exploring further aspects of digital signal processing. The book is your tour guide during your first steps of your journey. ----Richard G. Lyons
Understanding DSP, Second Edition
The field of DSP has grown to be important both theoretically and technologically. • Development and use of low-cost software and hardware • New tech. and app. take advantage of DSP algorithms
Understanding DSP, Second Edition
Chapter 1 Discrete Sequences and Systems
Understanding DSP, Second Edition
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Outline
1.1 Discrete Sequences and Their Notation 1.2 Signal Amplitude, Magnitude, Power 1.3 Signal Processing Operational Symbols 1.4 Introduction to Discrete Linear Time-Invariant Systems 1.5 Discrete Linear Systems 1.6 Time-Invariant Systems 1.7 The Commutative Property of Linear Time-Invariant Systems 1.8 The Causality Property of Linear Time-Invariant Systems
{x(n)} is a complex sequence if x(n) is complex. {x(n)} = {xre(n)} + j{xim(n)}
x(n) is a finite length sequence if it is defined only for a finite time interval as: N1≤n≤N2.