Modulated Wave Power Spectrum Analysis

The research of the power spectrum of modulated signal makes use of probability and statistic theory according to the limited observation data to analyze spectrum, and distributing of analyzed signal's energy with frequency distribution bas been given, and it is a basis for subsequence automatic recognize of modulation schemes, demodulation, and so on by dint of signal dealing technology and rapid computer dealing ability. The power spectrum of modulated signal is applied abroad for civilian communication and army communication, such as the management and supervising of wireless spectrum, communication counterwork, and so on, specially, for non-operation communication, such as signal affirming, disturbing recognizing, electronic counterwork, communication counterwork, military threatening analysis, and so on.It is a simple method for the power spectrum density with moving period chart, and is a low resolving ratio method for spectrum estimation. The method of modern spectrum estimation is a high resolving ratio method making use of the parameter model. This paper has analyzed and discussed for the methods of ARMA spectrum estimation, maximal entropy spectrum estimation, MUSIC spectrum estimation, Pisarenko resonance wave resolving, expanding Prony, and so on. Establishing signal model of modulation scheme in common use, ARMA random process model has been set up, and the power spectrum of modulated signal has been simulated making use of ARMA organic process model.This paper has been set up AWGN and non-AWGN channel models, and nine signal models have also been set up, such as AM, OOK, SSB, FM, PSK, QPSK, FSK, MSK and GMSK, and the characteristic of AWGN and non-AWGN channel models has been summed up, and the time field and spectrum field of the nine signals has been analyzed, and their closed expression of the time field and spectrum field has been derived of. With AWGN and non-AWGN channels separately, the basic signal being random process, carrier frequency and SNR being set, the arithmetic of the power spectrum of modulated signal has been designed, and the computer simulation platform has been set up, too, and the wave form photos of the power spectrum of modulated signal of the nine signals have gained directly, and the time has been registered for classical spectrum analysis method and modern spectrum analysis method.Results of simulation have showed that the higher resolving ratio and less analysis time can be got making use of parameters model to realize arithmetic for the power spectrum of modulated signal.