窄带假设对GNSS天线阵抗干扰性能评估的影响分析

The Influence Analysis of Narrowband Hypothesis to GNSS Array Anti-jamming Performance Evaluation

传统方法基于窄带假设条件下的模型对天线阵抗干扰性能进行评估,存在分析精度低的问题。新一代全球卫星导航信号带宽的增加使得宽带效应更为明显,影响将更为严重。因此,窄带假设所造成的影响需要重新审视。论文结合当前普遍采用的数字域加权处理方式,推导出天线阵处理频率响应的精确模型,得出阵列处理响应在频域上可表示为空域导向矢量与时间矢量的Kroneck积与阵列加权值的内积。并分析了多种条件下窄带假设引入的阵列增益评估误差,分析表明,窄带假设条件下对阵列处理频率响应描述失真是其对阵列增益评估引入误差的根本原因。在干信比70dBc时,最大误差可达5dB以上,干扰强度增加时,误差进一步加大。而采用上述推导的精确模型,误差约为0.5dB。

The traditional method analyzes the anti-jamming biases by using narrow-band model Hypothesis.On the other hand,next-generation GNSS signals using wider bandwidth make the broadband effect more obviously.Therefore,the impact of narrow-band assumptions needs to be re-examined.This research derives the precise model under the case of DBF processing,and the conclusion is that the array response equals to the inner product of spatial steer vector and the Kroneck product of time steer vector and weights of taps.The research also analyzes the array anti-jam performance biases by narrowband assumption under the multiple factors.The results show that the main reason is the distortion of array response.When JSR is 70dBc,the maximum error introduced by narrow-band approximation model is about 5dB.The intenser the jamming,the bigger the error.At the same time,the error introduced by the above precise model is about 0.5dB.