中文摘要：

针对4-WFRFT隐蔽通信系统，非目的接收机在一定时间内仍能有效的通过参数扫描获得解调参数的不足，提出了一种采用双层多项多参数加权分数阶傅里叶变换（DL-MPWFEFT）与星座扰乱的卫星隐蔽通信系统。在多参数WFRFT的基础上提出了DL-MPWFRFT，通过星座图的研究，分析了DL-MPWFR—FT信号的隐蔽原理与特性，为进一步增加信号的隐蔽性，信号在DL-MPWFRFT变换后又增加了星座扰乱相位。最后，从误码率的对比，参数扫描次数两方面分别定性定量的说明了所提系统的抗截获性优势。通过对系统误码率进行对比仿真分析，发现即使信噪比达到15dB时，非目的接收机解调误码率仍在0．4以上。非目的接收机通过参数扫描获得正确解调参数，需进行（M／O．0005）^2次扫描。

英文摘要：

Aimed at the problem that within a certain time, the non target receiver can still get the parameter of the demodulation parameters effectively through parameter scanning in the 4-WFRFT covert commu- nication system, this paper proposes a satellite covert communication system by using the double layers multiple parameter weighted-type fractional Fourier transform （DL-MPWFRFT） and constellation scrambling is proposed. The paper proposes DL-MPWFRFT based on multi parameter WFRFT. The hiding principle and characteristics are analyzed through the research of constellation. Though increasing the signal concealment, the constellation scrambling phase increases again after DL-MPWFRFT signal conversion. Finally, from two aspects, the comparison of error rate and the number of parameter scans, the anti interception advantages of the proposed system are described qualitatively and quantitatively. By comparing the BER of the system, the result shows that even if the SNR is 15 dB, the BER of the non target receiver is still more than 0.4. The non purpose receiver obtains the correct demodulation parameters by parameter scanning, which needs （M/0. 000 5）^2 scans.