Abstract: The article presents digital methods for processing the complex signal in the acoustic processor of a sonobuoy. The overall system design and the complex signal are presented. Two alternative methods for signal processing are discussed: in the time domain and in the frequency domain. Block diagrams of the algorithms of both processing methods are included. The problems involved in the practical implementation of data analysis methods are discussed. The problems are produced by the phenomena occurring in the system’s analogue section and by the complexity of the computation related to how powerful the digital algorithms are. The computation errors in both methods are analysed. The advantages and disadvantages of the different signal processing methods are discussed, with emphasis on the practicality of the device. The advantage of the processing method in the frequency domain is explained. Graphic images of the results of both processing methods are included on the example of real signals received during the study.