Abstract:A method of spectrum analysis is proposed using recursive least square algorithm to train the weights of Fourier Basis Functions (FBF) neural network. Its main idea is that the weights of the FBF neural network are trained with recursive least square algorithm, and then the amplitude spectrum and phase spectrum are computed according to the obtained weights. The approach is not involved in plural multiplication operation and plural addition operation. Software and hardware of the approach are easily implemented. It is especially fit for the implementation of software and hardware of DSP chips. The results of spectrum analysis show that the method presented has not only high accuracy and fast convergence speed but also filtering function. Therefore, it is an effective approach of spectrum analysis.