Circuit arrangement for automatically recognizing the line standard of a video signal

摘要

A circuit arrangement for automatically recognizing the line number of a video sync signal in accordance with the 525 or 625 line standard automatically generates a control signal corresponding to the relevant line number. A line counter (14) is clocked with horizontal frequency pulses and receives the frame-frequency sync pulse signal as a reset signal. A decoding stage (15) is arranged at the output of the line counter (14) and supplies a signal for changing the line standard hitherto used and a signal characterizing the corresponding line standard. In a subsequent signal evaluation circuit (16), these two signals are checked and a control signal either corresponding to the current line standard or to the new line standard is applied to the output (17).