| 摘要 |
PURPOSE:To normally process the character signal of the teletext of a coding transmission system by providing a service indentification means for identifying the service identification SI included in the character signal superimposed during a horizontal scanning period and detecting the service identification SI of the teletext of the coding transmission system. CONSTITUTION:The service identification means 14 detects the service identification SI in the character signal by the character signal (a) and a clock signal. A gate signal generation ROM 16 outputs the gate signal of a width slightly wider than a timing at which the SI is detected by using the output of a counter 15. A latch means 18 is reset by a horizontal synchronizing pulse (b) and holds the output (f) of an AND circuit 17 as shown in (g). A service identification memory 20 stores the output of the latch means 18 correspondingly to an address outputted from an address counter 19. Then, the writing to the service identification memory 20 is performed after the output of the latch circuit 18 is defined.
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