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AssigneeMatsushita Electric Corporation of America
InventorsFrancis H. Hilbert, Theodore S. Rzeszewski
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A low level video auxiliary signal is transmitted in addition to the conventional composite black and white or color television signal. The auxiliary signal is in the form of redundant, opposite-polarity signal portions during pairs of time successive signal portions, such as horizontal lines or fields of the composite television signal. The auxiliary signal also may be transmitted in the form of a predetermined frequency with the auxiliary information on successive lines of the composite television signal being out of phase by one-half the period of the auxiliary signal frequency. When the composite signal is detected and displayed by the conventional circuitry in the receiver, the auxiliary information is visually cancelled in the image displayed on the cathode ray tube and the normal video information is displayed. Additional circuitry is employed in the receiver to effect cancellation of the conventional video information from the display and to reinforce successive portions of the auxiliary signal; so that the auxiliary signal is displayed on the cathode ray tube of the receiver when desired.
A television receiver for selectively displaying conventional television signals and auxiliary television signals on the cathode ray tube thereof, wherein the conventional television signals comprise a composite signal containing at least video information and horizontal and vertical synchronizing signal components, and said auxiliary signal components comprise alternating signal portions containing opposite-polarity, redundant information during successive ones of the signal portions thereof, said receiver including in combination:
Dependencies are inferred from the claim text.