窄带实高斯噪声对外差式零拍装置的干扰机理

Jamming mechanism of narrowband real Gaussian noise against heterodyne homodyne device

以外差式CW多普勒引信为例分析了外差式零拍装置提取差频信号的基本原理,把外差式零拍装置在数学层面上抽象为对线性叠加信号求平方后提取低频分量的模型。根据该模型,从理论上证明了:窄带实高斯噪声单独通过外差式零拍装置后输出的低频噪声的带宽将得到加倍,噪声与本振信号相互作用后产生新的噪声分量将使低频噪声功率比无本振信号时得到增加;回波信号加窄带平稳实高斯噪声通过零拍装置后干信比将得到增强,且增强的程度将随本振信号功率的增加而降低。计算机仿真分析的结果验证了上述结论,也正好解释了早期CW引信极易受到频率对准噪声干扰而早炸的实际情况。

Taking CW Doppler fuze for an example to illustrate the principle of distilling difference frequency signal, heterodyne homodyne device is model as squaring linearly additive signals and passing lowpass filter mathematically. Based on this model, it is analyzed that the bandwidth of low frequency noise will be doubled and the power of effective interference noise will be upgraded by local oscillator signal when narrowband real Gaussian noise pass heterodyne homodyne device alone. In order to analyze jamming-to-signal ratio change after echoed signal and noise passing the heterodyne homodyne device, jamming-to-signal ratio improvement rate is defined and calculated. It outcomes that jamming-to-signal ratio improvement rate is negative and tend to decrease as power of local oscillator signal increasing in this case. Computer simulations testify the results and correspond the fact that CW fuze is fragile against narrowband noise.