基于椭圆球面波信号的多支路连续相位调制解调方法

针对现有甚低频通信模式通信速率较低、频带利用率不高的问题，探索研究一种基于椭圆球面波信号的多支路连续相位调制解调方法。具有时频域高能量聚集性的椭圆球面波信号引入连续相位调制，利用椭圆球面波信号完备正交特性，将不同阶椭圆球面波信号同时作为连续相位调制的基带调频脉冲信号，产生多支路连续相位调制信号；在信号接收端，利用传统差分相干检测对信息符号序列映射信息进行解调，通过对多个比特周期内信号求互相关值和的方法，实现椭圆球面波波形映射信息的检测与解调。仿真实验结果表明：该多支路连续相位调制解调方法与目前甚低频通信采用的最小频移键控调制模式相比，在调制信号99.9%功率带宽条件下，可有效提高频带利用率约9.43%；但在调制信号99.0%功率带宽条件下，频带利用率会降低约1.24%.

Multi-branch Continuous Phase Modulation and Demodulation Method Based on PSWFs Signal

A multi-branch continuous phase modulation and demodulation method based on prolate spheroidal wave functions (PSWFs) signal is studied for the problems of low communication rate and low spectral efficiency in the existing very low frequency (VLF) communication mode. Through introducing the PSWFs signal with high energy aggregation in the time-frequency domain into continuous phase modulation and using the complete orthogonal characteristics of the PSWFs signal, the PSWFs signal with different orders are simultaneously used as the continuous-phase modulated baseband frequency-modulated pulse signals, thereby generating a modulated signal. At the signal receiving end, the traditional differential coherent detection method is used to demodulate the mapping information of information symbol sequence. And then the method of obtaining the sum of cross-correlation values of the signals during multiple bit periods is used to detect and demodulate the PSWFs waveform mapping information. The experimental results show that, compared with the minimum frequency shift keying modulation mode currently used in VLF underwater communication, the spectral efficiency can be effectively improved by about 9.43%, but it can be reduced by about 1.24% under the condition of 99.0% power bandwidth of modulated signal.