一种高效、灵巧的多通信信号产生方法

针对通信对抗复杂战场电磁环境模拟的要求,设计并实现了一种资源高效利用、样式灵活可变、参数实时可控的多通信信号产生方法。该方法经过高速缓存循环读取、通用数字正交调制、法罗滤波器内插和多通道信号合成后,产生多路不同体制、不同样式的通信信号来模拟复杂战场电磁环境。在XC6VLX240T FPGA上,对信号产生方法进行了软硬件[1]实现,通过DAC5688在140 MHz中频,60 MHz带宽内输出多路信号模拟。结果表明,该方法能够同时产生10路样式、码速率、幅度、频率均实时可变的常规、扩频、数据链或跳频通信信号,中频带外抑制优于60 dB,带内互调失真优于40 dB。

Numerical investigation of efficient synthetic jets generated by multiple-frequency actuating signals

The synthetic jets generated by multiple-frequency actuating signals composed of a basic sinusoidal wave and a superposed high-frequency signal is investigated by two-dimensional simulation in the present study.The effect of the frequency and amplitude of the high-frequency signal on the synthetic jet in the quiescent flow is investigated in detail with stroke length ratio L and Reynolds number Re_(U0)kept as constant.It is found that,with the high-frequency signal superposed,the vortex pairs induced by the synthetic jets are strengthened and accelerated.The distance that the vortex pairs can propagate downstream is also elongated.The entrainment of the synthetic jets is thus enhanced as well.The optimal design is reached when the frequency ratio,defined as the ratio between the superposed signal frequency and the basic signal frequency,is fixed at f^(+)=2.At this optimal frequency ratio,the jet entrainment increases monotonously with the amplitude of the high-frequency signal.