分析采用EBPSK/DSB—AM复合调制的AM广播发射信号功率谱,给出复合传输系统的结构和发射信号的波形表达式.以美国FCC规定的功率谱发射掩模和我国关于AM发射机基本参数的国家标准为具体指标,对比了通过几种不同的发射滤波器后复合凋制信号的功率谱结构,以及相应的数据传输性能.系统仿真表明,在满足给定发射信号功率谱衰减和一定的信噪比条件下,模拟AM广播和EBPSK数据传输都能获得良好的性能.
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.