TV receiver with video-text module - has PLL producing sync. signals with output derived from frequency divider when no TV signal is received

摘要

A pulse separator (9) takes signals from the receiver (1) and separates out videotext signals, as well as line and image sync. signals. An oscillator (10) clock synchronises a data processor (7) and a character generator (8). A frequency divider (11) divides the clock, which is at an integral multiple of the line rate, and produces line rate outputs to a phase comparator (12) in a control loop. The drive and image sync. signals, for text mode without simultaneous from a t.v. transmitter, are derived from the output signals of the divider. ADVANTAGE - No t.v. reception needed, allowing display of any desired text. @(4pp Dwg.No.1/1)