公开(公告)号：NO744473A

公开(公告)日：1975-08-25

申请号：NO744473

申请日：1974-12-11

Applicant: RCA CORP

Inventor： LIMBERG LEROY A ,  STECKLER S A

IPC: H04N5/04 ,  H04N5/06 ,  H04N5/08 ,  H04N5/12 ,  H04N5/213

CPC classification number: H04N5/12

公开(公告)号：NO744473L

公开(公告)日：1975-08-25

申请号：NO744473

申请日：1974-12-11

Applicant: RCA CORP

Inventor： LIMBERG LEROY A ,  STECKLER S A

IPC: H04N5/06 ,  H04N5/04 ,  H04N5/08 ,  H04N5/12 ,  H04N5/213

Abstract: A dual mode deflection synchronizing system includes a resettable counter which generates noise-free internal synchronizing signals and signals representative of the interval during which external vertical synchronizing signals should be received provided the counter is properly synchronized. A sync signal verification detector is coupled to the source of external vertical sync signals and to a mode switch so that if the external signals arrive during this prediction interval as determined by the sync signal verification detector the system continues to operate in a synchronized mode on its internally generated synchronizing signals. If the external signals do not arrive during this prediction interval, the mode switch switches the system into a non-synchronized mode. A vertical sync signal detector which is also coupled to the source of external sync signals and to the mode switch begins to search for an external signal which has the time duration characteristic of an authentic external synchronizing signal. Until such a signal is received, the system continues to be synchronized by internal synchronizing signals generated by the resettable counter. When such a signal is received, the vertical sync signal detector resets the counter to correct its synchronization with the received external vertical synchronizing signal and toggles the mode switch to return the system to its synchronized mode of operation.