In the modern world, with the surge of usage of the unmanned aerial vehicles many tasks related to detection of aerial objects have arisen and also the determination of their type within the cities and the countryside. Such tasks are the recognition and classification of aerial objects using radar stations. Aerial objects that need to be detected usually are unmanned aircraft and birds. Processing the signal received by radar from the aerial object to obtain a proper spectral signature is needed to solve such tasks. The most informative detail for determining the type of the aerial object is the presence or absence of the micro-Doppler effect in the spectral signatures. The perpose of this paper is to carry out and compare two strategies for filtering echo signals from interference and obtaining their spectral signatures. The first strategy involves application of several methods for filtering the echo signal, followed by a standard spectral analysis. The second strategy adds to the previous one the use of an autocorrelation and calculating spectral density. Comparison of the of the applied strategies for processing echo signals from aerial objects showed that the use of the autocorrelation results in a more pronounced, regular and refined spectral signature relative to the first approach with only filtering and spectral analysis. The application of these strategies for processing signals reflected from aerial objects will be used in a future research to design a system with deep integration of the physical and computational components.