Abstract: A received video signal, in which a complete picture is made up of two line-interlaced picture fields that are successively transmitted, is converted in two different ways into respective video signals of the same vertical scan frequency in which a full complement of television lines is provided in each vertical scan interval. In a first conversion favorable to picture contents in which there is considerable motion, there are added, to the lines of one picture field of the received signal, a set of interpolated lines derived from the lines of that field. In a second conversion designed to avoid flicker at horizontal edges in the picture, the lines of two successive picture fields of the received signal are used to make up a full complement of lines. Both conversions involve time-compressing the lines so that a full complement of lines can be transmitted in a vertical scan interval.

Abstract: A protective circuit for a semiconductor laser supplied with an excitation current by a current generator circuit is created using a transducer, whose output is controlled by the laser light, a limit circuit cooperating with the transducer and a current shunt circuit energized by the limit circuit and switched in parallel with the semiconductor laser. Once the permissible emitted light power is reached, excessive excitation current is diverted to the shunt circuit. Exemplary embodiments of the invention are found to achieve response times below 20 ns and are able to protect the semiconductor laser from overload currents even during power-on and power off.

Abstract: A circuit for the conversion of an electrical input signal into an optical output signal is disclosed. A portion of the main beam from a laser diode that provides the optical output is reflected to a PIN diode with a glass pane. Linearization of the electro-optical conversion process over a wide frequency range is achieved through a feedback loop. For operation at frequencies higher than that of the feedback loop bandwidth, the various conversion factors for low and high frequencies can be additionally adapted.

Abstract: A safety device for a light signal generator only activates a laser beam emerging from an optical fiber connector when an optical fiber is connected. By inserting a plug of the optical fiber into the connector of the light signal generator a photodetecting circuit is caused to provide a control signal, which activates the laser.