公开(公告)号：EP0132988A3

公开(公告)日：1986-03-26

申请号：EP84304877

申请日：1984-07-18

申请人： AMERICAN TELEPHONE AND TELEGRAPH COMPANY

发明人： Debus, Walter, Jr. ,  Osborne, Thomas Lawrence ,  Siller, Curtis A., Jr.

IPC分类号： H04L25/497

CPC分类号： H04L25/497

摘要： A digital synthesis technique provides pulse shaping in accordance with predetermined time domain and frequency domain constraints. In the technique, the informational content of a binary bit stream is used by an access circuit (12) to form address words for accessing a read-only-memory (13). The digital representations stored in the ROM (13) represent a superposition of temporally-displaced truncated impulse time functions, each weighted by the discrete transmission symbol levels of the analog output signal. The digital representations from two ROMs (13-1 and 13-2) are toggled by a sequencing circuit. In other embodiments of the invention, different memory arrangements ranging from a single ROM (142) to an array of ROMS (163-1 through 163-3 and 164-1 through 164-3) are respectively used to decrease circuit complexity. In a digital radio transmission application of the technique, this arrangement is economical, readily reproducible and stable since it obviates the need for conventional complex analog filters.