Light road construction machinery such as manually operated reversible plate compactors or reversible vibratory plates are used for compacting sand, gravel, rock fill, soil, etc. with the aid of vibration. The purpose of the vibration excitation of the ground is to produce pressure waves that penetrate the ground layers to overcome the resisting friction between the soil particles, in order to reduce the soil porosity and permeability. During compaction, the ground is dynamically excited via a compactor's bottom plate. However, the actual spatial dynamic behaviour of a compactor's bottom plate during operation may not be known. To increase the knowledge concerning the spatial dynamic behaviour of a compactor's bottom plate during operation, a reversible plate compactor whose bottom plate has been considered as a rigid body in its design has been investigated. An increased knowledge concerning the dynamic behaviour of compactor's bottom plate during operation is likely to enable a further improvement in the design of reversible vibratory plates concerning their performance, vibration exposure of operator, etc. To acquire knowledge concerning the dynamic behaviour of the bottom plate of a reversible vibratory plate during operation, spatial measurements of its acceleration response have been carried out on it during operation on rubber mats. Operating deflection shape analyses of the bottom plate have been carried out based on both power spectral density estimates and power spectrum estimates of the recorded acceleration responses. The fact that the frequency of the vibration excitation of the reversible plate compactor varied slightly, and thus induced a frequency modulated vibration response of the plate, was considered in the ODS analysis. The analyses indicate different dynamic behaviours of the bottom plate depending on the operation of the reversible vibratory plate, i.e. if it operates in idle, reverse or forward motion.