A system designed for absolute activity measurement is described using a digital method. The system is based on data recording from a coincidence measurement and subsequent software processing of the data records. The data acquisition device collects amplitudes of individual pulses from analogue-to-digital converters and supplies them with time information. Software processing of data records from this system offers many benefits in comparison to conventional coincidence counting, for example it enables to perform time and pulse height analysis and setting of coincidence parameters by using a wide variety of evaluation methods to one data record. The digital system was tested with a 4pi beta-gamma coincidence detectors arrangement consisting of a proportional counter and two NaI(Tl) scintillation detectors. The results obtained with a 60Co source are presented.