TRANSMITTER, RECEIVER AND TRANSMISSION DEVICE

摘要

PROBLEM TO BE SOLVED: To attain both NTSC and HDTV broadcasts in the satellite broadcasting by including the information in the information on the placement of signal points to decide every threshold group. SOLUTION: A modulator 4 shifts the signal points to other points set on a space diagram so as to set the minimum distance at (2δ×S) between both adjacent signal points. Then m pieces of signal points can be discriminated from each other by a 1st threshold group which divides the space diagram into m pieces of areas, and n pieces of signal groups can be discriminated from each other by a 2nd rough threshold group which divides the space diagram into n pieces of areas. The signals sent from a transmission part 5 include the information on the placement of m pieces of signal points set on the space diagram, and this information includes the information which is needed for deciding the 1st and 2nd threshold groups. In this example, 2δshows the minimum distance set between both adjacent signal points among m pieces of signal points which are equidistantly placed to each other and S shows a variable shift extent (S>=1).