Font Size: a A A

All-Phase Digital Signal Processing

Posted on:2008-09-08Degree:DoctorType:Dissertation
Country:ChinaCandidate:X D HuangFull Text:PDF
GTID:1118360245990871Subject:Signal and Information Processing
Abstract/Summary:PDF Full Text Request
In order to solve the problem of performance degradation which arises from sequence truncation in many digital signal processing occasions, this dissertation proposes a lot of improved methods based on'all-phase digital signal processing', involving the fields of digital filtering, spectrum analysis, signal reconstruction and statistical signal processing etc.Firstly, the general calculating formula for the coefficients of all-phase equivalent FIR filter under arbitrary orthogonal transform is deduced. And the interpolation method based on convolution-window's spectrum function and cyclic shift figure method are respectively applied to deduce the frequency response function of all-phase filter in DFT domain, which can interpret the reason that all-phase design method with single window is fit to design those filters with discontinuous frequency character. Moreover, quantitative analysis on the computation complexity and flexibility of all-phase filter's 5 equivalent structures is given in details.Secondly, both the changes of determined signal's waveform & spectrum and the changes of stationary random signal's mean value & variance after all-phase pre-processing are studied. And a novel'even symmetric'frequency sampling mode is introduced. By this mode, two kinds of all-phase filter design methods based on double phase-shifting combination and frequency character compensation are respectively proposed. In addition, the technique of frequency response masking and the technique of all-phase filtering based on even symmetric frequency sampling are incorporated, so the problem of controlling boundary frequency bands is solved. Moreover, the notch filter whose notch frequency point can be shifted arbitrarily is successfully designed. To overcome the deficiencies of big waveform distortion and Gibbs effect in conventional discrete Fourier reconstruction, a novel all-phase Fourier reconstruction algorithm is proposed. It is also pointed that the all-phase Fourier reconstruction and all-phase FIR filter design are uniform indeed.Both of them reflect that all-phase method is fit to discontinuous signal's processing. Lastly, the mechanism of all-phase FFT (apFFT) spectrum analysis is deeply studied. The viewpoint that 2 sub-spectrums can adaptively adjust the performance of apFFT's spectrum is proposed and proved. Four basic properties of apFFT spectrum analysis are discovered, among which the property of square relation between the apFFT spectrum amplitude and the conventional FFT spectrum amplitude for single-frequency complex exponential sequence as well as the property of'phase invariant'are strictly proved. Several correcting spectrum methods based on apFFT are expatiated, among which all-phase time-shifting phase difference correcting method has the highest precision. This paper also applies apFFT and the corresponding correcting spectrum methods into many aspects such as phase meter design, feeble signal detection, harmonic analysis of power system, radar velocity measuring,laser wavelength measuring etc.
Keywords/Search Tags:All-phase digital signal processing, Even symmetric frequency sampling, Frequency response masking, Spectrum analysis, Correcting spectrum
PDF Full Text Request
Related items