高动态软件接收机自适应门限快速捕获算法

Adaptive threshold fast-acquisition method for high dynamic software receiver

为了解决高动态环境中软件接收机的捕获问题。探讨了信号捕获的原理,针对高动态情况下多普勒频移大的特点,提出采用快速傅里叶变换方法对高动态环境下的卫星导航信号进行捕获。在信号检测上,指出了卫星导航信号的检测其实就是二元假设检验的问题,推导出了在恒虚警概率条件下门限的计算公式,讨论了门限与环境噪声的关系。然后,给出了该算法的方框图并在此基础上对该算法进行Matlab仿真。仿真结果表明,该算法在虚警概率恒定不变的情况下,能够在几十秒内捕获信号,而传统算法的捕获速度通常需十几分钟。

For solving the acquisition problem of software receiver in high dynamic environment, this paper discussed the principle of signal acquisition. And the fast fourier transfer method was proposed to capture the satellite navigation signals because of the larger doppler shift in the high dynamic environment.In the aspect of signal detection, it was shown that the detection was the problem of two terms hypothesis test and the threshold equation was deduced in the constant false alarm probability.Above all, the relationship between the threshold and the environment noise was discussed.Then, the algorithm block diagram was given and the method was simulated in PC based on Maflab. Simulate experiments prove that the method could acquire the satellite signals in dozens of seconds in the condition of constant false alarm probability while the tradi- tional acquisition method commonly uses tens of minutes to acquire the signal.