| 摘要 |
<p>A signal extraction circuit for extracting desired reference information from a base signal, such as a composite television signal. The circuit arrangement is particularly useful in extracting the Vertical Interval Reference (VIR) signal which is customarily included at line 20 in both television fields. The circuit arrangement includes a detector to respond to the color burst segments of the composite signal. The color bursts are converted to pulses and utilized to condition a counter to begin counting to a preselected count level or number following the resumption of color bursts after the vertical interval. Upon reaching the set count level, a control signal is generated to switch on a bistable device or the like to provide an appropriate gating signal time-coincident with the desired reference signal information to be extracted. The amount of reference information extracted is made adjustable by controlling the width of the gating signal. Accordingly, any or all of the reference information may be extracted from the associated horizontal line interval of the composite television signal.</p> |
