Abstract: A method, a communications system and a receiving device are for billing of access-controlled programs and/or data which are broadcast by a broadcast transmitter unidirectionally and encrypted, and are received by at least one receiving device. A monetary value is stored in a data memory of the receiving device. The costs for access to the access-controlled programs and/or data are determined in the receiving device based on received cost data, and decryption of the access-controlled programs and/or data in the receiving device is prevented if the determined costs are greater than the stored monetary value. Billing records are generated in the receiving device for the allocation of credit items to the vendors of the access-controlled programs and/or data, and are transmitted to a billing center via various data channels.

Abstract: A method and a communications system are for billing of access-controlled programs and/or data, which are broadcast unidirectionally and encrypted from a broadcast transmitter and which are received by at least one receiving device. The programs and/or data broadcast encrypted are decrypted in the receiving device for access if received access conditions data for the access-controlled programs and/or data coincide with authorization data for the user. Clearing data from the central unit are thereby transmitted to a clearing module. The clearing data include billing data for the access to the unencrypted access-controlled programs and/or data as well as user data. The central unit makes available to the vendor information relating to the user data, in accordance with the received clearing data, which information is generated by the central unit according to specified conditions on further use.

Abstract: A method for a secure transmission of information between a first and a second module is disclosed. Each module contains one of the keys of two pairs of keys. A first number and a second number are randomly generated in the first module, and a third number is randomly generated in the second module. A check is made that a random number encrypted by one of the modules, then decrypted by the other, then re-transmitted re-encrypted to the initial module, is after decryption in the latter identical to the original random number. In each of the modules a common session key K is created independently with at least three same numbers generated randomly partially in one module and partially in the other module. Information transmitted between the two modules is encrypted with the common session key.

Abstract: A scrambling method wherein each image line (23-309) of a frame having been produced in unscrambled form before being scrambled, is given the pseudorandomly determined address (B) of the memory line in the storage memory (8) in which said image line is to be stored on reception; and wherein the moment (or the running order) for broadcasting said image line is determined so that on reception, the image line causes, because it is stored in the memory line to which it was addressed, the image line previously stored at the same address to be output to the television set at the right moment (or in the right order) so that an unscrambled picture is reconstructed.

Abstract: A decoder comprising a microprocessor connected to a receiver of data of teletext and to a text generator for displaying information on the screen of a television receiver. Further, a CPTV-card (card pay-television) is associated with the microprocessor, this card managing the credit necessary for the purchase of emissions, for the memorization of the emissions purchased and for permitting the unscrambling of the emissions purchased by delivering to the microprocessor the input pointer in the sequence which is calculated by the microprocessor by means of the information which has been memorized as well as the information delivered by the decoder. The programs of the forecasted emissions are transmitted by the head station and memorized in the microprocessor of the decoder. Another memory of the microprocessor contains the instructions for the manipulations to be effected for selecting an emission and for purchasing it as well as for recharging a credit in the CPTV-card.

Abstract: According to the invention, on the emitter side, a number generator (10) delivers a random code (XAL) which is sent to the input of a master card (11) which ciphers such code according to a predetermined key (100), the code thus ciphered is broadcast with the video signal, a first device (17) receives, on the one hand, the random code (XA) and, on the other hand, the code ciphered by the master card (11) and effects a predetermined numerical combination of these two codes, such combination forming the initialization word of a pseudo-random generator (12) intended to provide a table of codes for scrambling the video signal and, on the receiver side, the ciphered code received is deciphered by a customer card (13), a second device (18) receives at the inputs, on the one hand, the ciphered code and, on the other hand, the code deciphered (XA) by the customer card (13) and effects a numerical combination of these two codes which is similar to the combination of the first device (17).

Abstract: A tachometer assembly comprises two toothed rings (68, 70) in approximate axial register. The rings have similar peripheries of which the teeth (69, 71) are closely spaced in the axial direction of the rings. Magnetic flux in a path extending axially of the teeth varies as the rings rotate and is sensed by a coil (74) disposed coaxially of the rings.

Abstract: A control system for a motor which drives a tape capstan includes a capacitor (91) which holds a sample of a ramp signal which is sampled and restarted in response to tachometer pulses. The output of an amplifier (90, 100) which amplifies the difference between the stored voltage and a reference is integrated by a passive integrator (106, 92) coupled to the capacitor (91). The arrangement provides prediction of change of a discontinuous speed signal and is useful for slow running motors of low inertia.

Abstract: A self-contained reel hub assembly for a tape transport. The hub assembly comprises a housing including a base and a side wall which upstands from and extends around the periphery of the base. Within the housing defined by the side wall is the rotor and the stator winding of a motor. The rotor drives a sun wheel which engages a plurality of planet wheels each of which protrudes laterally from the side wall of the housing. A rotatable hub is mounted on a central post extending upwardly from a frame member forming a top cover for the housing. The hub member includes a peripheral part which extends around the side wall of the housing and carries a ring of inwardly directed gear teeth engaged by the planets. The planets are linked by a carrier which permits limited movement of the planets relative to the carrier.

Abstract: A tape loop sensing arm comprises an arm member (6) which carries a rotary guide (5), comprising a cylindrical guide member (74) mounted on a spindle (65) which pivots on an axle (64) aligned radially with respect to the axis of rotation of the arm member.

Abstract: A tape loop sensing arm is mounted for rotation with a plate (31) which extends into a core (37) and carries shaped lossy strips (34) for altering the quality factor of a coil (36) carried by the core.