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为了实现弱信号环境中的高灵敏度GNSS信号跟踪,提出了一种改进的非相干GNSS信号频率锁定方法,利用非相干累积消除电文反转的影响,扩展有效能量累积时间范围,改善了信噪比;设计了基于非线性加权累积偏差的最优频率间距计算方法,得到频率鉴别线性范围最大的非相干频率鉴别器;通过延长相干和非相干累积时间,实现宽线性鉴频范围的高灵敏度频率锁定环路.理论分析和蒙特卡罗仿真结果表明:所提出的方法可以改善频率跟踪灵敏度和牵引范围,在不进行电文估计、静态环境信号强度为-160dBm的情况下,可以实现稳定跟踪并保证一定精度.
In order to realize high sensitivity GNSS signal tracking in weak signal environment, an improved frequency locking method for non-coherent GNSS signals is proposed. By using non-coherent accumulation to eliminate the effect of message reversal, the range of effective energy accumulation time is extended and the signal-to-noise ratio ; The optimal frequency spacing calculation method based on non-linear weighting cumulative deviation is designed to obtain the incoherent frequency discriminator with the largest linear range of frequency discrimination. By prolonging the coherent and non-coherent accumulation time, a high sensitivity frequency locking Loop.The theoretical analysis and Monte Carlo simulation results show that the proposed method can improve the frequency tracking sensitivity and the traction range without the message estimation and the static signal strength of -160dBm can achieve stable tracking and ensure a certain Accuracy.