【摘要】 在电离层中传播的短波信号会受到多径传播、多普勒频移和扩展以及衰落的影响,这样会使信息传输的错误比特率增加。OFDM是一种能有效降低多径传播对信号影响的调制技术,而采用DAPSK调制技术可以降低接收设备的复杂度。主要分析了在不同组合方式下(16DPSK/4DASK,16DPSK/4ASK,16PSK/4DASK)64DAPSK-OFDM系统的性能,仿真结果表明,16PSK/4DASK-OFDM在AWGN信道和HF信道下都优于其他2种组合方案的64DAPSK-OFDM系统。更多还原

【Abstract】 HF transmission signals are distorted by multi-path propagation,Doppler spread and signal level fading in the ionospheric channel.In the case of digital transmission systems,the distortion of signals will cause a degradation of bit error performance.The OFDM modulation scheme can mitigate the adverse effects of multi-path fading.And the DAPSK modulation scheme can reduce the complexity in implementation.Performance of 64DAPSK is analyzed, with three combination methods considered,such as 16DPSK/4DASK,16DPSK/4ASK,and 16PSK/4DASK.Simulation adopted 64DAPSK-OFDM is done in AWGN channel and HF channel.And the result shows that performance of 16PSK/4DASK-OFDM is better than that of others.更多还原