| 摘要 |
PURPOSE:To keep the continuity of serial numbers and transmission data to a constant value by storing a transmission scanning line number when synchronism discontinuity takes place in a storage circuit, generating the serial numbers based on the storage number and using the output of the 2nd counter based on the storage number thereby discriminating the end of protection data transmission by the 2nd comparator circuit. CONSTITUTION:When discontinuity takes place in a synchronizing signal at switching of a video signal or the like, a horizontal scanning number at discontinuity detection is stored in a storage circuit 111, the synchronization discontinuity is informed to a control circuit 101 to changeover a switching circuit 104 to the position of protection data transmission. A comparator circuit 112 compares the horizontal scanning number stored in the storage circuit 111 with contents of a counter 110, and when they are coincident, a flip-flop 113 is set. A comparator circuit 119 compares the field number preset in a protection period setting circuit 120 with contents of a counter 115, and when they are coincident, a flip-flop 118 is set to change over the switching circuit 104 to the output position of the transmission data storage circuit 102 and the protection data output end is informed to the control circuit 101. |
