The main tasks of ground surveillance radars for security and perimeter protection are detection and classification of moving ground targets. In typical radar systems, target detection is fully automated, but the target classification requires human involvement. In this paper, we consider received radar echoes data of ground moving targets, and corresponding signals in timefrequency domain using spectrograms and cepstrum. The objective of the paper is to identify and validate the intrinsic features characterizing the different classes of targets, and subsequently extract salient features for classification. We will show examples on Radar Echoes Database. This database, named RadEch Database, cointaines radar echoes that are collected in controlled test enviroments at the premises of Military Academy-Republic of Serbia. Database purpose is to enable reproducible research results in the field of classification of ground moving targets (pattern recognition).