CHANNEL CODING APPROACHES AND CONSEQUENCES - SINGLE AND DUAL CARRIERS

One of the key technical challenges to providing a terrestrial high-de finition broadcast television service in the U.S. is to simulcast the new service into the same spectrum space occupied by present-day NTSC television. Since both NTSC and high-definition television (HDTV) must coexist during a transition period, the optimum utilization of availa ble spectrum for HDTV requires achieving a low level of interference b etween NTSC and HDTV stations. Both single-carrier and dual-carrier tr ansmission systems have been proposed for HDTV and this paper examines some of their fundamental strengths and weaknesses. Based on an overa ll consideration of the latest computer analysis of HDTV and NTSC serv ice areas and other factors, it is concluded that a single-carrier app roach is preferred.