Abstract: Method and arrangement for marking a video or audio signal to assign a classification to said signal, for example, to identify that the signal is authentic and may not be copied. The signal comprises at least two components (Y, UV) according to a predetermined standard (MPEG, PAL, NTSC). According to the invention, values are assigned to said components which in combination can normally not occur. For example, in black picture portions where Y, U and V are all zero, U and/or V are now wilfully made non-zero to constitute the watermark. Television receivers still display said black portion. The watermark is not lost when the signal is re-encoded and copied on a recordable disc. A player will not reproduce the copy because the watermark no longer corresponds with the "wobble key" of the new disc.

Abstract: An arrangement (60) for recording an analog signal in a track on a record carrier (82) is provided with an overload detection circuit (78) for detection an overload situation for the analog signal applied to the arrangement. Upon detection of an overload situation, the recording mode is terminated and the record carrier is rewound to the start location of the current recording. Further, the arrangement is provided with a variable attenuator (66). The variable attenuation factor in the attenuator is increased upon detection of the overload situation.

Abstract: An arrangement (60) for recording an analog signal in a track on a record carrier (82) is provided with an overload detection circuit (78) for detection an overload situation for the analog signal applied to the arrangement. Upon detection of an overload situation, the recording mode is terminated and the record carrier is rewound to the start location of the current recording. Further, the arrangement is provided with a variable attenuator means (66). The attenuation factor in the variable attenuator is increased upon detection of the overload situation.

Abstract: A semiconductor laser/amplifier is disclosed in which the radiation oscillates only in one longitudinal mode. According to the invention this is achieved by a strip-shaped active region which exhibits periodic variations in amplification (and preferably also in the amplification profile) in its longitudinal direction over at least a part of its length. The period of the amplification variation is at least ten times the wavelength of the radiation.