A novel phase parameter estimation method of quadratic FM signal based on Sigmoid fractional ambiguity function in impulsive noise environment

To overcome the limitations that the second-order statistics based methods rely heavily on gaussianity assumption and the fractional lower-order statistics based methods depend on the priori knowledge of non-Gaussian noise, two novel concepts, the Sigmoid transform based instantaneous correlation function and Sigmoid transform based fractional ambiguity function, are defined firstly. Based on these definitions, a novel phase parameters estimation method of the quadratic FM signal is proposed in impulsive noise environment. Furthermore, the property of the Sigmoid transform is presented and proved. Simulations have verified its superior performances over existing methods based on fractional ambiguity function or fractional ambiguity function based on fractional lower order statistic, especially under impulsive noise. Meanwhile, it does not depend on the priori knowledge of noise.