The purpose of the study was to develop a briefing note that covered the issues concerning the amount of radio spectrum required by terrestrial television services once they have migrated from analogue to digital transmission. The note explores the different digital TV technologies used around the world (PAL, ISDB, ATSC).  It also considers the other technical issues, such as the different types of networks, that influence the amount of spectrum required by broadcasters.   It also looked at what had happened in those markets that had moved from analogue to digital television in the Americas, Europe and Asia.