统一的BPSK信号功率谱分析

Unitive Power Spectra Density Analysis of BPSK Signals

二进制移相键控BPSK调制是载波相位按基带脉冲而键控改变的一种数字调制方式,其功率谱推导在传统上也是按照将基带脉冲的频谱左右频移进行的,因而要求频移后的谱没有混叠,即只有高载频才能忽略近似性,具有一定的局限。本文按照直接载波调制的思路,推导出BPSK已调信号功率谱的准确表达式,既消除了高载频的限制,也统一了对于BPSK功率谱的基带分析和载波分析方法。仿真结果表明了新表达式的正确性。

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.