Abstract: Power spectrum density (PSD) analysis for hybrid modulated signal is presented in the paper. The system, which combines extended binary phase shift keying (EBPSK) with double sideband amplitude modulation (DSB-AM), is introduced, and its waveform expression given. With regard to FCC’s(federal communications commission) AM spectral emission mask and China’s national standards on AM transmitter, comparisons are made on the effects of taking different band-pass filters into the hybrid system, and on the demodulation performances. Computer simulations demonstrate that good performance of both modulations can be obtained at certain SNR within the given PSD constraint.

Key words: power spectrum density (PSD), AM, EBPSK, FCC spectral mask