Sgs-thomson Microelectronics S.a.

Thomson Multimedia S.a.

Thierry Meunier

Michel Imbert

Video signal synchronization extraction device

A device for adjusting a video signal so that its black level is in coincidence with a predetermined reference level includes a capacitor having a first terminal that receives the video signal and a second terminal that provides the adjusted video signal, and means for discharging the capacitor at a constant current when the adjusted video signal exceeds the reference level, and for charging the capacitor at a constant current when the adjusted video signal is below the reference level, the ratio between the charging and discharging currents ranging from 4.3 to 12.6. The device further includes means for significantly reducing the current ratio at least during a portion of a frame synchronization pulse train.

Device for adjusting the black level of a video signal

A system for adjusting filters processing the composite video signal in a multistandard set by determining the tuning phases during the quiescent phases of the composite video signal. A reference signal (f.sub.ref) is applied to the filter during the tuning phases; a phase-locked loop supplies an error signal corresponding to the phase-shift of the filter; and means (14) are provided for storing the error signal of the phase-locked loop.

System for adjusting filters processing the composite video signal in a

An automatic connection circuit on either of the input terminals of a TV set, each of these inputs receiving video signals according to one of several standards, comprising a standard identification circuit (10) and a selection circuit (11), the identification circuit sending an inhibition signal (IN) to the selection circuit when it has detected a selected standard; a switch (14), the first terminal (12) of which is connected to the input of the identification circuit and the second terminal of which is connected to either of the input terminals by the action of a control signal (16); a divider (15) receiving a periodic signal and providing a signal for controlling the selection circuit according to a first period and the switch according to a half period, this divider being inhibited by said inhibition signal.

Automatic connection system on a color TV S-VHS input

The present invention relates to a differential amplifier with differential outputs comprising a reference input, a signal input, a first (2) and a second (3) low-pass filter respectively connected with a differential output and with a comparator input (4), the comparator output being connected with the reference input of the amplifier in order to form a regulation loop which compensates for the d.c. level variations of the signal applied to the signal input and which servo-controls the d.c. level difference of the outputs to a value approaching zero. The invention applies to integrated circuits with differential amplifiers.

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Voreppe, France

Thierry Meunier