Acousto optic signal processing is a sort of technology of spectrum analysis and correlation, taking acousto optic device as the core, with the features of large instantaneous bandwidth, dynamic range, processing gain and high speed parallel capacity. According to the principle of incoherent time integrating correlator, the methods of polynomial fitting and wavelet transform are used to resolve the problem of correlation peak extraction of baker code. At last, experimental results and comparison of two methods are also given.