预检测GNSS信号建模方法及Viterbi频率跟踪算法

GNSS Pre-Detection Signal Modeling Method and Viterbi-Based Frequency Tracking Algorithm

对中频和零中频全球卫星导航系统(GNSS)信号数学模型进行推导,并进一步提出预检测GNSS信号建模方法,针对3种GNSS信号数学模型给出统一的噪声施加方法,通过理论分析和仿真证明基于3个模型的仿真平台具有等效性,预检测仿真平台等效地将数据采样率降低至1000 Hz左右,降低了运算量,提高了仿真效率。提出基于Viterbi算法的频率跟踪方案,通过回溯法进行频率估计,基于预检测仿真平台进行仿真验证,静态场景下可以跟踪载噪比为10 dBHz的弱信号。

The mathematical models of intermediate frequency and zero intermediate global navigation satellite system(GNSS)signal are deduced.The pre-detection GNSS signal model is further proposed.A unified method is proposed to add noise for the three signal models.The theoretical analysis and simulation results show that the simulation platforms based on the three model are equivalent.The predetection simulation platform reduces the data sampling rate to about 1000 Hz and reduces the amount of computation,and the simulation efficiency is improved.A frequency tracking scheme based on Viterbi algorithm is proposed,in which the frequency is estimated by traceback approach.This tracking scheme is verified on the pre-detection simulation platform and the results show that the proposed method can track GNSS signal for a carrier-to-noise ratio of 10 dBHz in static scene.