低信噪比下线性调频信号的检测和高精度参数估计

Detection and High Precision Parameter Estimation of LFM under Low Signal to Noise Ratio

Radon-Ambiguity变换(RAT)在低信噪比(SNR)下对线性能调频信号具有良好的检测和参数估计性能。RAT仅需一维搜索,比Radon-Wigner变换具有更高的运算效率。为了实现高精度参数估计缩小搜索步长而仍采用直接搜索时,运算量仍然比较大。本文提出了高效的RAT二次搜索方案来解决这个问题。该方法有2个步骤,在检测阶段,通过RAT分辨率公式求出保证最大检测概率的最大搜索步长;在估计阶段,通过Cramer-Rao界求出保证估计精度的最大搜索步长,该方法能大大减少RAT的计算量。新方法的性能为蒙特卡洛仿真所证实。

Radon-Ambiguity transform （RAT） has good performance for detection and parameter estimation of linear frequency modulated signals （ LFM ） under low signal to noise ratio （SNR）. The computational burden is heavy when a direct search with a very fine step is employed for high precision parameter estimation of LFM. In this paper, an efficient double search strategy of RAT is proposed to solve this problem. This strategy is composed of two stages ： in the detection stage, the maximum search step is calculated using the resolution formula of RAT to ensure a maximum detection probability; in the estimation stage, the maximum search step is calculated using the Cramer-Rao lower bound to ensure a high precision estimation. The computation task of RAT can be reduced drastically using our method. The expected performance of the new method is verified by Monte Carlo simulations.