Abstract: The invention relates to a device supplying an electrical signal for which a characteristic, for example, the voltage is adjustable. The device has a connector at one end of a cable to supply this signal to another electrical device. This connector comprises a transmission means of a light signal for which a visible characteristic depends upon the electrical signal produced. One improvement consists in the light signal coming from a source of white light that is colour modulated by filters. These filters are mechanically integrated into a mobile part belonging to the adjustment means of the signal supplied. The invention also relates to a system comprising the device supplying the signal and the device to be connected, the latter device features a mark identifying the light signal compatible with the electrical signal to receive.

Abstract: The invention relates to a device supplying an electrical signal for which a characteristic, for example, the voltage is adjustable. The device has a connector at one end of a cable to supply this signal to another electrical device. This connector comprises a transmission means of a light signal for which a visible characteristic depends upon the electrical signal produced. One improvement consists in the light signal coming from a source of white light that is colour modulated by filters. These filters are mechanically integrated into a mobile part belonging to the adjustment means of the signal supplied. The invention also relates to a system comprising the device supplying the signal and the device to be connected, the latter device features a mark identifying the light signal compatible with the electrical signal to receive.

Abstract: In order to scramble as effectively as possible pay-television transmissions, the transmitter is made to transmit, at one and the same time, access messages and entitlement messages, all of them crypted and corresponding to a control word periodically loaded into a pseudo-random generator. In each receiver, the decoder comprises a control unit processing the various messages and sending them to a security processor which supplies a control word to the pseudo-random generator controlling the unscrambling.

Abstract: The method of the invention consists, during the transmission of composite video signals, in the inclusion therein of series of access messages (ECM1, ECM2) and, during the unscrambling, carried out using a chip card reader whose chip card comprises encoded digital data, in using an interactive method of identification of a digital signature.