PROGRAM INDEX DATA ERASING CIRCUIT OF CHARACTER BROADCAST TELEVISION RECEIVER

摘要

PURPOSE:To skip a channel over which character broadcast service is not offered by monitoring a framing code detection output and then clearing a program number memory when the ceasing of said output is detected continuously for a specific time. CONSTITUTION:A framing code detection pulse FT is conducted from a framing code and timing pulse generating circuit and a gate pulse CG for extracting a character signal is also conducted from a gate pulse generating circuit. The pulse FT is inputted to an AND gate 14 through an inverter 13 and the pulse CG is inputted as it is; the output of the AND gate 14 is conducted to the clear input of a counter 15 and the gate pulse CG is conducted to the clock input of the counter 15. Further, a flip-flop 16 which receives the prescribed counting output of the counter 15 as a clock input and the output of the AND gate 14 as a clear input is provided and its output Q is applied to the clear terminal of the program number memory in a character signal processing circuit.