Backporch gating pulse generator subject to disabling during vertical

Abstract

In a TV receiver, a line-rate gating pulse generator includes a source of line-rate timing pulses of 'backporch' timing relative to the horizontal blanking intervals of received TV signals. Normally, the time constant of a capacitor charging circuit, enabled by the leading edge of each timing pulse, is determinative of a fixed, finite width for output gating pulses which are generated in response to the timing pulses. However, during the appearance of a field-rate pulse (e.g., vertical drive pulse), the charging circuit is altered such as to establish a zero width for the output gating pulses, resulting in a desired field-rate blanking of the line-rate gating pulse output.