This disclosure describes a circuit which is gated to amplify the video portion of a television signal to the exclusion of its synchronizing components, and which permits the amplitude adjusted, the gated signal to be adjsuted, yet without altering the value of its black level.
The present invention provides a clamp circuit for clamping a video signal which includes a sync tip clamp circuit, a pedestal clamp circuit, and a direct current electrical potential correcting circuit. The sync tip clamp circuit clamps a sync tip of the horizontal synchronization signal of the composite video signal at a first reference electrical potential when a clamp pulse is not received in a pulse input terminal, and outputs the composite video signal to an output terminal. The pedestal clamp circuit clamps the pedestal DC electrical potential of the composite video signal received to the video signal input terminal to the second reference electric potential when the clamp pulse is received at the pulse input terminal, and outputs the composite video signal to the output terminal. The direct current electrical potential correcting circuit adjusts DC power levels of the composite video signals in response to the output signal of the first reference electrical potential from the sync tip clamp circuit and the output signal of the second reference electrical potential from the pedestal clamp circuit. According to the present invention, the composite video signal is not largely changed even if the clamp pulses drop out.
A method and circuit to strip the composite synchronization (sync) from a composite video signal is disclosed. This invention utilizes a phase-locked loop and a switchable input operational amplifier to remove the sync portion of the video signal without bandlimiting or introducing non-linearities to the video signal. The phase-locked loop creates a high frequency clock from which a signal can be created that fully encompasses the sync portion of the composite video signal. This signal controls the switchable input operational amplifier to select blank level voltage during sync or allow the video to pass when sync is not present.
A bus line installation for the transmission of informations between a plurality of transmitters and a plurality of receivers. The signals transmitted by the bus line are optical signals. Each receiver comprises opto-electronical means for the transformation of optical energy into electrical energy and means for bringing the electrical signals representative of said transformation to the shape for which a part of the receiver similar to that of a bus line installation transmitting electrical signals is operative.
