By Tom Williams, Cable Television Laboratories, Inc.
Digital technology has progressed to the point where it is possible to remove ghosts from television pictures by using baseband digital filters. However for the digital filters to work, they must be programmed with the correct set of coefficients. The best way to determine coefficients is to put a training signal in the vertical interval and analyze the received training signal. The Advanced Television Systems Committee (ATSC) is sponsoring an effort to select a voluntary standard training signal. The committee work is being carried out by the ATSC T3,S5 specialist group. The effort consists of off-airfield tests by the National Association of Broadcasters (NAB), lab tests and computer simulation by the Canadian Research Center (CRC), and cable lab and field tests by CableLabs. The BTA ghost cancelling system is currently in use in Japan. This paper discusses the CableLabs tests and results.