Data dropper frames are transmitted on uplink command from the ground station or based on command stored inside on-board mission planner. Dropper is a software component facilitating unidirectional broadcast of data for any number of receiving stations. The data frames may contain arbitrary data from the on-board storage (as the main transmission), to be collected by amateur ground stations. Structure of dropped frames is defined in this document: https://www.pilsencube.zcu.cz/vzlusat2/vzlusat2_ham.pdf
VZLUSAT-2 is fully supported in SatNOGS ground station network: https://db.satnogs.org/satellite/DJWH-7860-9983-7310-6047 Also a public dashboard is available, constructed from beacon data: https://dashboard.satnogs.org/d/L8ywE9oMz/vzlusat-2 The source set of two line elements (TLE) for antenna tracking, Doppler compensation and satellite pass prediction will be published as soon as it is known.