公开(公告)号：WO1985005525A1

公开(公告)日：1985-12-05

申请号：PCT/US1985000844

申请日：1985-05-09

Applicant: ZENITH ELECTRONICS CORPORATION

Inventor： ZENITH ELECTRONICS CORPORATION ,  AULD, Frederick, H., Jr. ,  WALKER, David, L.

IPC: H04N07/167

CPC classification number: H04N7/1713

Abstract: A non-linear sync signal processor for deriving a sync-like signal from video information with suppressed sync signals includes a differentiating circuit (18, 20) for deriving pulse potentials from the leading and trailing edges of suppressed sync signals, a pair of comparators (30, 40) for generating signals corresponding to the pulse potentials and a pair of non-retriggerable monostable timers (50, 60), one (60) for creating a 6 microsecond first window in response to a leading edge and the other (50) for creating a 58 microsecond second window in response to a trailing edge occurring in the first window. The second timer (50) is enabled by operation of the first timer (60) and the first timer (60) is inhibited during operation of the second timer (50). Thus only sync-like signals having three characteristics of conventional sync signals are regenerated.

公开(公告)号：WO1985002743A1

公开(公告)日：1985-06-20

申请号：PCT/US1984001996

申请日：1984-12-07

Applicant: ZENITH ELECTRONICS CORPORATION

Inventor： ZENITH ELECTRONICS CORPORATION ,  CITTA, Richard, W.

IPC: H04N07/16

CPC classification number: H04N7/16 ,  G08C15/00 ,  H04N7/165 ,  H04N7/17363

Abstract: In a two-way cable television (CATV) system, multiple subscriber address codes are provided during designated vertical blanking interval (VBI) lines of the video signal transmitted from the CATV headend to a plurality of system subscriber terminals. Each subscriber terminal is provided with a decoder in which is stored subscriber unique address code for comparison with the received subscriber address codes. If there is an address match, an address match latch (AML) signal is generated for each VBI line address match. The address match signals thus generated from a multibit pulse coded downstream command signal for initiating various functions in the CATV system, e.g., acknowledging subscriber upstream requests, subscriber interrogation, power adjustment, etc.