Abstract: Aiming at the high cost of the AP algorithm’s computation in the signal processing ，an improved method has been proposed in this paper.Firstly the modulus maximum of the signal is calculated by the Ad hoc algorithm in the improved method，then the signal estimated coefficients of wavelet can be obtained from the parabola’s inserted value of subsection between the points of modulus maximum，finally the purpose of denoising can be achieved by the signal reconstruction based on these coefficients.The simulation results show that the method can filter noises effectively and the principle of the method is more simple and which makes the program can be completed more easily and the speed of denoising is higher and the method is more practical compared with AP algorithm，especially more convenient to realize it by hardware.

Key words: wavelet transform, denoising of modulus maximum, Alternating Projection（AP） algorithm

摘要： 针对信号处理中交替投影法去噪计算量大的缺点，提出了改进方法，改进后的方法首先利用Ad hoc算法求出信号的模极大值，然后对模极大值点分段进行抛物线插值，从而得到信号的估计小波系数，最后利用估计小波系数重构信号，实现去噪的目的。仿真实验证明：该方法能有效去除噪声，与交替投影法相比，该算法在原理上更简单，程序实现更容易，去噪速度更快，是更加实用的方法，特别是便于用硬件实现。

关键词: 小波变换, 模极大值去噪, 交替投影法