june 1982. See also ELINT/ESM Kopáč - the first generation Czech ESM TDOA system Tamara - the third generation Czech ESM TDOA system VERA - the current and fourth generation Czech ESM TDOA system Kolchuga - a similar system developed in the Ukraine Literature Jiří Hofman, Jan Bauer: Tajemství radiotechnického pátrače Tamara [The Secret of Radiotechnical Sensor Tamara], 2003, , in Czech. Describes three generations of the sensors: PRP 1 (1964), Ramona (1979) and Tamara (1989). Jiří Hofman worked in the development of the sensors. Peter Emmett: Silent Trackers: The specter of passive surveillance in the information age, in Air Power, summer 2002 issue Military equipment of Czechoslovakia Radiofrequency receivers Science and technology in Czechoslovakia