Unitive Power Spectra Density Analysis of BPSK Signals

BPSK is a digital modulation scheme,whose carrier phase,controlled by keying,is changed according to baseband impulse.Traditionally,its power spectra density(PSD) is obtained by shifting the spectra of baseband impulse,therefore,it is demanded that the spectra shifted does not overlap,which means that very high carrier frequency is needed to eliminate this approximation.A new idea about direct carrier modulation is presented in this paper,and then an exact formula of BPSK PSD is deduced from a new angle,which has no restriction on carrier frequency and unifies the PSD analyses both in baseband and in radio frequency.Also computer simulation illustrates that this new PSD expression is correct.