Classification in L-Band of Physical Activities Performed Simultaneously into the Forest by a Group of Persons

The Doppler frequency signature and the cadence frequency of a couple of people moving simultaneously into the forest are presented in this paper. A brisk walk and a run have been analyzed in L-band. The results are based on measured data that have been collected by a bistatic radar working in continuous wave (CW). The purpose of the analysis is to assess the reliability of the short-time Fourier transform (STFT) and of the cadence frequency diagram to distinguish two physical activities performed simultaneously in a forested area and recorded at 1 GHz. Obstructing trees and small movements of the undergrowth largely impacted the spectrogram, making it difficult to interpret. Instead, the cadence frequency looks reliable for detecting the two activities and distinguishing them from the surrounding vegetation.