Abstract: The cloning source of an authorized receiving device cannot be identified. A key distribution system 1 concerning the present invention includes: a communication channel 10; a key distribution center 11; a server 12; and receiving devices 13a to 13n. The key distribution center 11 distributes, to the server 12, the information necessary for distributing shared keys SK to the receiving devices 13a to 13n, and distributes the individual information group EMMG necessary for receiving the shared keys SK from the server 12. The server 12 generates the shared keys SK, generates the common information ECM based on the shared keys SK and the system secret variable group set SPGS, and distributes the common information ECM to the receiving devices 13a to 13n. The receiving devices 13a to 13n obtain the shared keys SK based on the individual information group EMMG and the common information ECM and outputs them to outside.

Abstract: Channel selection unit selects a channel of a desired program from a digital broadcast signal in which an ECM and an EMM are multiplexed. Separation unit separates the ECM and the EMM. EMM decoder decodes the EMM. A first key is obtained from the decoded EMM. ECM decoder decodes the separated ECM using the first key. A second key is obtained from the decoded ECM. Viewing enabling determination unit determines whether or not to enable viewing of the program. A system controller communicates with an information server through a network interface part at the time of work key non-setting, and an OSD display processing unit is made to generate an image for displaying information provided.

Abstract: A reproducing apparatus has a communication unit which receives distribution of contents from a server device via a network, a decoding unit, a reproducing unit, and a control unit which controls to when encrypting and distributing divided contents of the contents from plural modules owned by each of plural server units owned by the server device, distribute distribution information showing each one of the divided contents to be supplied from which one of plural module units in the plural server units, plural decoding keys depending on each module unit of each server unit, and plural divided contents individually encrypted by the plural decoding keys, from the server device via the communication unit, to decode the plural divided contents by the decoding unit on the basis of the distribution information and plural decoding keys, and to reproduce the decoded contents.

Abstract: In the CATV communication system, each channel comprises a down control channel which employs a carrier wave (fd0) and accommodates a down delay control channel slot and down assignment control channel slots therein, a plurality of down communication channels which employ carrier waves (fd1 to fd4) different from that employed in the down control channel and accommodate down communication data channel slots therein, and a plurality of up channels which employ carrier waves (fu0 to fu3) and accommodate up delay control channel slots, up assignment control channel slots, and communication data channel slots therein.

Abstract: A remote control system which can control a plurality of remote control units (RCUs). The remote control system includes a first memory for storing an RCU identification code for each of the remote control units, a second memory for storing a maker identification code for the remote control apparatus corresponding to the RCU identification code, a model code, and a remote control code. The system further includes a device for reading an active remote control code from the second memory on the basis of the RCU identification code read from the first memory according to the apparatus control request from an active remote control unit. Electromagnetic waves or infrared rays act as a second modulated wave which is modulated on the basis of the active remote control code in order to control the function of the remote control apparatus corresponding to the active remote control code. The plurality of remote control units are managed by a single remote control reception and processing device.

Abstract: There is provided a method with which the expansion of CATV services and the diversity of subscribers' needs can be dealt with flexibly, it is easier to maintain and expand the apparatus, the system can be operated simply, and the parental control function is also simple. A head end and a subscriber terminal unit have two-way communication means and are connected to each other via a two-way transmission line. The HIB and subscriber remote control units each have two-way communication means. The output of HIB is supplied to various types of apparatuses. The HIB can also exchange data with an expansion unit. To control various types of apparatuses with a remote control unit, the remote control unit communicates with the HIB, receives the necessary data under the control of HIB, and together with HIB, controls various types of apparatuses.

Abstract: A transmitter encoder has a gain selector for compressing the level of a horizontal sync signal component of a video intermediate frequency (IF) signal to scramble it, and an AM modulation degree controller for superposing a control signal, which indicates the timing for the level compression, on an FM audio IF signal in the form of AM modulation. The transmitter encoder further has an oscillator circuit for generating a sine wave with a horizontal frequency (fH) and an nfH sine wave having a frequency n times the horizontal frequency, and a mixer for mixing these sine waves to thereby provide the above control signal. A receiver decoder has an AM detector for detecting an AM component of the FM audio IF signal from the transmitter encoder to reproduce a composite signal and band filters for respectively extracting the fH and nfH sine waves from the reproduced composite signal.

Abstract: An external control unit for a CATV system has a CPU and a RAM with many kinds of memory maps. Reference data to be stored in the memory maps is transmitted from a central station. When a subscriber requests the tuning of a TV channel for a pay program to a converter tuner, the CPU in the external control unit can work, using the reference data.

Abstract: A variable frequency oscillator includes a RAM which stores a frequency setting data and provides a frequency control data, a VCO circuit which provides an oscillation output having a frequency which is defined by the contents of the frequency control data, a reference oscillator which provides a reference signal having a given frequency and phase, a phase comparator which detects the phase difference between the reference signal and a comparison signal corresponding to the oscillation output, and a logic circuit which combines the frequency control data with a phase data and provides the frequency setting data. The phase comparator provides the phase data whose contents indicate +1 if the phase of the comparison signal is delayed from the phase of the reference signal, indicate -1 if the phase of the comparison signal is advanced to the phase of the reference signal, and indicate 0 if the phase of the comparison signal matches with the phase of the reference signal.