The ARSR/SSR video signals are used for enroute ATC. They are transmitted from remote radar sites to the Area Control Center (ACC) using the Nippon Telegraph & Telephone Corporation (NTT) analog telephone lines in a band-compression mode. The analog transmission, however, is being replaced by the digital transmission in Japan, and this replacement required an urgent development of a new radar video signal transmission technique for NTT's low-capacity digital lines. This paper presents a proposal that MTI/SSR signals indispensable for ATC services are transmitted in real time and that NORM signals which have a lot of information are transmitted at a comparatively low speed. The evaluation experiment was performed and its effectiveness was validated.