Description of a computer–controlled polarimetric system for atmospheric studies of scattered radiation of optical and radio–frequency ranges is presented. The system provides recording of temporal and angular distribution of the Stokes vector parameters in active and passive modes. In signal recording the measuring system starts automatically if a number of conditions set by the program for optical and radio pulses are met. The recorded signal is digitized with a variable step of timing beginning from 100 ns. In so doing a background component preceding the signal is also stored in memory. Calibration and tests are conducted with digital metrological means generating pulses with preset temporal and polarization characteristics. The system control, data processing and presentation are made by a computer.