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Research On The Phase Trajectory Control Method Of CPM Signals

Posted on:2014-04-12Degree:MasterType:Thesis
Country:ChinaCandidate:X X HuangFull Text:PDF
GTID:2268330425965961Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
With the rapid development of wireless communication technology, the number of userscontinues to grow, and the spectrum resources become increasingly nervous, the systemrequires a higher demand of the digital modulation techniques, and the general digitalmodulation technology can not meet the stringent requirements of modern communication.With the characteristics of higher frequency utilization rate, low band energy radiation, phasecontinuous and constant envelope, the continuous phase modulation (CPM) signal are moreand more concerned, in CPM signal the characteristics of phase change trajectory is one of theimportant factors affecting the quality of its spectral characteristics, on this point, this paperconduct a further research on the smoothing method of the CPM signal’s phase changetrajectory, the purpose is to further improve the CPM signal’s frequency spectrumcharacteristics.This paper first detailed introduces the basic principle of continuous phase modulation,and then used the determined function and optimization function, it realizes a full responseCPM signal’s phase trajectory smoothing process, it gives the program of using orthogonalmethod to realize CPM signal modulation and demodulation, finally, it realizes the CPMsignal’s simulation process using MATLAB.Using determined function, that is the sine and cosine functions, polynomial functionsand atomic functions, we obtains the CPM signal’s frequency modulation function and phasemodulation function. The trajectory of the phase change of the CPM signals not onlycontinuous, but the higher derivative, and then it analyzes the spectral characteristics, andcompares with the spectral characteristics of the conventional signal.In the implementation of CPM signal phase trajectory smooth process using optimizationfunction, it introduces the minimum band energy radiation criteria, establishes a mathematicalPan-function model using variational method, meanwhile, it attaches single symbol signalenergy limit, the peak to average power ratio and the boundary conditions. By introducingLegendre series, using the numerical method it realizes the solution process of optimizationfunction, then obtaines the CPM signal frequency modulation function and phase modulationfunction, and conducts the frequency spectrum analysis and comparison. It determines the quadrature modulation and coherent demodulation scheme of the obtained CPM signal, andrealizes the CPM signal’s simulation process using MATLAB.The results prove that: it is a feasible method to realize full response CPM signal phasetrajectory smoothing using the determined function and the optimization function, Theobtained CPM signal with the characteristics of higher derivative phase continuous, higherspectrum roll-off speed and smaller out-band energy radiation achieve the intended purpose.
Keywords/Search Tags:Phase smoothing, Continuous phase, determined function, optimizationfunction, Legendre Series
PDF Full Text Request
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