抗干扰GPS接收机中角度、频偏和时延的联合估计及跟踪方法

Joint angle, frequency and delay estimation method in anti-interference GPS receiver

  • 摘要: 全球导航卫星系统(Global Navigation Satellite System ,GNSS)应用广泛,但是卫星信号很小,容易受到干扰。传统的使用功率倒置的方法使用空时级联的方式,只能对所有导航卫星形成一个波束,限制了干扰的抑制性能。本文以GPS为例,提出了一种基于空时联合处理的多天线抗接收机的结构。在捕获阶段,先利用子空间分解求出干扰空间,进行投影后利用GPS信号结构实现角度和小数倍频偏的联合估计,从而分别对每颗卫星做波束形成,提高了干扰抑制能力。在跟踪阶段,在单天线跟踪环路的基础上增加角度跟踪环路,实现同时对角度、频偏、时延的跟踪。与已有的基于空时联合处理的方法相比,本文方法在不降低性能的前提下降低了实现复杂度。数值仿真结果表明,捕获阶段角度估计性能得到了提升,捕获概率增大,抗干扰能力也较传统的功率倒置方法有了大幅提升。

     

    Abstract: The Global Navigation Satellite System (GNSS) is widely used, but the satellites are far from the ground, so the signal is weak and susceptible to interference. The traditional method of power inversion algorithm uses space-time cascading, which can only form one beam for all navigation satellites, limiting the performance of interference suppression. Taking GPS as an example, this paper proposes an anti-interference receiver structure based multi-antenna which include two stage: the acquisition stage and tracking stage. In the acquisition stage, interference space is selected after subspace decomposition. Then the received signal is projected into a space orthogonal to the interference space. Next, the angle and fractional frequency offset can be estimated using the periodicity of the satellite signal. At last, beamforming each satellite separately, the delay and integer frequency offset can be estimated. In the tracking stage, comparing to the single-antenna tracking loop which only track frequency offset and delay, an angle loop is added to simultaneously track the angle. In addition, the computational complexity is quantitatively analyzed. Compared to other anti-jamming algorithm without tracking angle, the complexity of the proposed algorithm is less. Finally, the simulation results show that the angle estimation performance of the acquisition stage is improved, the acquisition probability is increased, and the incident angle of the satellite signal can be effectively tracked. The anti-interference ability is also improved greatly compared with the traditional power inversion method.

     

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