测量与信号基础英文PPT (28).pdf

ContentsChapter 1 IntroductionChapter 2 Time Waveform Analysis Chapter 3 Frequency Spectrum Analysis Chapter 4 Amplitude Possibility AnalysisChapter 5 Time delay Correlation AnalysisChapter 6 Time-varying signal analysisChapter 7 Signal FilteringChapter 8 Principles of sensorsChapter 9 Signal conditioning techniqueChapter 10 Characteristics of measurement systemsChapter 11 Computer based measurement systemsSignal analysisMeasurementFundamentals of Measurement and Signal Analysis7.1 Concept of signal filtering7.2 Frequency-domain filtering 7.3 Time-domain Filtering and Z-Transform7.4 FIR Filter7.5 IIR FilterChapter 7 Signal FilteringFundamentals of Measurement and Signal Analysis7.1 Concept of signal filteringIn a signal,there are always some parts of unwanted components,such as electromagnetic interference and background noise.They affect the signals quality seriously.1)Noise and interferenceElectromagnetic interference7.1 Concept of signal filteringAviation noiseInsect noise7.1 Concept of signal filteringIn these conditions,we need to eliminate interference components to improve the quality of the signal.This process is called signal filtering.Noised signalNoiseFiltered signal7.1 Concept of signal filtering2)Signal filteringTimeAmplitudeFrequencyWaveformSpectrumSignal filtering is a process to reduce or remove unwanted frequency components of the input signal in order to create a new clean signal.Conditions:the interference signal and the measurement signal are in different frequency bands.X7.1 Concept of signal filteringExperiment:)2002sin(410)1502sin(310)1002sin(210)502sin(10)(tttttxPass-Band of FilterFiltered signal waveform and spectrum7.1 Concept of signal filtering3)Types of filterLow-pass filterHigh-pass filterBand-pass filterBand-stop filterH(f)fStop bandPass bandH(f)fH(f)fH(f)fStop bandStop bandPass bandPass bandStop bandStop bandPass bandPass band7.1 Concept of signal filtering)2002sin(410)1502sin(310)1002sin(210)502sin(10)(tttttx7.1 Concept of signal filteringNotch filterPeak filterComb Peak filterComb Notch filter7.1 Concept of signal filteringBackground NoiseNoised audio signalComb filtered audio signal7.1 Concept of signal filtering4)Series and parallel connections of filtersBand-pass filter=Low-pass High-passBand-stop filter=？Homeworks1.What is the signal filtering,and in what conditions it can works well?2.If you have a iPhone,turn on and turn off the noise cancellation function,and talk to your friends in a noisy environment,then compare their different.7.1 Concept of signal filteringFundamentals of Measurement and Signal Analysis