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CHAPTER 1 Signals and Signal Processing. Wang Weilian wlwang@ynu.edu.cn School of Information Science and Technology Yunnan University. Outline. Characterization and Classification of Signals Typical Signal Processing Operations Examples of Typical Signals
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CHAPTER 1 Signals and Signal Processing Wang Weilian wlwang@ynu.edu.cn School of Information Science and Technology Yunnan University
Outline • Characterization and Classification of Signals • Typical Signal Processing Operations • Examples of Typical Signals • Typical Signal Processing Applications • Why Digital Signal Processing 云南大学滇池学院课程:数字信号处理
Characterization and Classification of Signals • Signals • In mathematics: a function of independent variables • In physics: anything that carries information • Examples: speech, music, picture, and video signals • Signal processing: • To extract useful information carried by the signal • In domain or in the transformed domain 云南大学滇池学院课程:数字信号处理
Characterization and Classification of Signals • Signal classification • 1-D / M-D signal • Scalar — vector • Real-valued— complex- valued • Continuous-time / discrete-time signals • Analog signal — digital signal • A sampled-data signal— a quantized boxcar signal • Deterministic / random signals 云南大学滇池学院课程:数字信号处理
Typical Signal Processing Operations • Elementary Time-Domain Operations • Scaling: • Integration: • Differentiation: • Delay operation: • Addition: • Product of two signals: 云南大学滇池学院课程:数字信号处理
Typical Signal Processing Operations • Filtering — convolutional integral • To improve the quality of the signal • To pass / block certain frequency components in a signal through the filter without any distortion • Categories • Lowpass filter • Highpass filter • Bandpass filter • Bandstop filter • notch filter • Multiband filter • comb filter 云南大学滇池学院课程:数字信号处理
Typical Signal Processing Operations • Generation of Complex Signals • A complex signal can be generated from a real signal by employing a Hilbert transformer • Method: • A real analog signal x(t) is passed through a Hilbert transformer • The continuous-time Fourier transform of is • The complex signal is 云南大学滇池学院课程:数字信号处理
Typical Signal Processing Operations • Modulation • Demodulation 低通滤波器 云南大学滇池学院课程:数字信号处理
Typical Signal Processing Operations • Multiplexing and De-multiplexing • For an efficient utilization of a wideband transmission channel • Quadrature Amplitude Modulation • Signal Generation • Square waves • Triangular waves • White noise 云南大学滇池学院课程:数字信号处理
Examples of Typical Signals • Electrocardiography ( ECG ) Signal • Electroencephalogram ( EEG ) Signal • Seismic Signals • Diesel Engine Signal • Speech Signals • Musical Sound Signal • Time Series • Images 云南大学滇池学院课程:数字信号处理
Examples of Typical Signals • Images Original Image Complement Image 云南大学滇池学院课程:数字信号处理
Typical Signal Processing Applications • Sound Recording Applications • Compressors and limiters • Expanders and noise gates • Equalizers and filters • Noise reduction system • Delay and reverberation systems • Special effects • Telephone Dialing Applications • Dual-tone multi-frequency ( DTMF ) • FM Stereo Applications • Electronic Music Synthesis • Echo Cancellation in Telephone Networks 云南大学滇池学院课程:数字信号处理
Why Digital Signal Processing • DSP everywhere 云南大学滇池学院课程:数字信号处理
Why Digital Signal Processing • Advantages: • Less sensitive to tolerances of component value • Enable to full integration • Any desirable accuracy • Timesharing • Easy adjustment of processor characteristics during processing • The impossible with analog implementation — linear phase, multi-rate processing … • Cascade without any loading problems • Stored almost indefinitely without loss of information 云南大学滇池学院课程:数字信号处理
Why Digital Signal Processing • Disadvantages: • The increased system complexity • The limited range of frequencies available for processing • Consume electrical power 云南大学滇池学院课程:数字信号处理
Summary • This chapter provides an overview of signals and signal processing methods. • The mathematical characterization of the signal is discussed along with a classification of signals. • A review of some commonly used signal processing operations is provided and illustrated through examples. • Advantages and disadvantages of digital processing of signals are discussed. • We hope that you can feel interesting and indulge in DSP. 云南大学滇池学院课程:数字信号处理