Abstract: A data player for reading contents encrypted by a decoding key from a digital medium, and playing the encrypted contents by using the decoding key which is stored in a key storage unit, comprises: a key obtaining unit for performing mutual authentication with the key storage unit to obtain the decoding key stored in the key storage unit; a key holding unit for holding the decoding key; a playback state obtaining unit for monitoring the playback state of the digital medium; and a contents decoding unit for decoding the encrypted contents by using the decoding key. The decoding key is obtained by the key obtaining unit and stored in the key holding unit, and the encrypted contents read from the digital medium is decoded with the decoding key by the contents decoding unit to play the contents. The decoding key stored in the key holding unit is discarded according to the playback state of the digital medium which is obtained by the playback state obtaining unit.

Abstract: A data player for reading contents encrypted by a decoding key from a digital medium, and playing the encrypted contents by using the decoding key which is stored in a key storage unit, comprises: a key obtaining unit for performing mutual authentication with the key storage unit to obtain the decoding key stored in the key storage unit; a key holding unit for holding the decoding key; a playback state obtaining unit for monitoring the playback state of the digital medium; and a contents decoding unit for decoding the encrypted contents by using the decoding key. The decoding key is obtained by the key obtaining unit and stored in the key holding unit, and the encrypted contents read from the digital medium is decoded with the decoding key by the contents decoding unit to play the contents. The decoding key stored in the key holding unit is discarded according to the playback state of the digital medium which is obtained by the playback state obtaining unit.

Abstract: A ring-shaped network quickly performs initialization even when a plurality of data transmission apparatuses are connected thereto. Each data transmission apparatus outputs received data to a device connected thereto while performing establishment of clock synchronization based on the received data, and when synchronization is established, it resends the received data. Further, when synchronization of the connected device is established, it sends data supplied from the connected device. Further, a master data transmission apparatus outputs data at turn-on of power or immediately after reset, and a next-stage slave data transmission apparatus receives the data to establish synchronization, and resends the received data when synchronization is established. Thus, synchronization of all the data transmission apparatuses is established while making a round of this data, and then synchronization of devices connected to the respective data transmission apparatuses is established.

Abstract: A data player for reading contents encrypted by a decoding key from a digital medium, and playing the encrypted contents by using the decoding key which is stored in a key storage unit, comprises: a key obtaining unit for performing mutual authentication with the key storage unit to obtain the decoding key stored in the key storage unit; a key holding unit for holding the decoding key; a playback state obtaining unit for monitoring the playback state of the digital medium; and a contents decoding unit for decoding the encrypted contents by using the decoding key. The decoding key is obtained by the key obtaining unit and stored in the key holding unit, and the encrypted contents read from the digital medium is decoded with the decoding key by the contents decoding unit to play the contents. The decoding key stored in the key holding unit is discarded according to the playback state of the digital medium which is obtained by the playback state obtaining unit.

Abstract: The data sending device (10) receives input biphase-mark-encoded sending data which is output from an apparatus on the sending side, and a biphase decoding section (12) biphase-mark-decodes the input sending data. The output data from the biphase decoding section (12) is transmitted to a data receiving device via a sending section (14). On the other hand, the data receiving device biphase-mark-encodes the data received from the data sending apparatus (10) and then supplies the data to an apparatus on the receiving side.

Abstract: A voice talk system 1 comprises a voice talk apparatus 11, and a voice talk control apparatus 13 which controls a talk between a sender's user and a receiver's user. In the voice talk control apparatus 13, after voice and additional information are received via a network 14, a database is searched using the received voice and additional information as search keys to specify a receiver's user. A grouping section groups the specified receiver's user(s) together. Further, a priority setting section is provided which assigns ordinal numbers as priorities for establishing a connection, to the receiver's users grouped by the grouping section.

Abstract: A data transmission device (1a) generates and transmits a lock signal for establishing clock synchronization with data transmission devices (1b-n). The data transmission device (1a) is capable of generating a pattern 1 lock signal for giving a notice of start of communication by use of data subjected to eight-value mapping, and a pattern 2 lock signal for giving a notice of start of communication by use of data subjected to four-value mapping. One of the two types of lock signals is transmitted to each data transmission device. Determining which lock signal has been received enables each data transmission device to give a notice of data communication method prior to training.

Abstract: To a data reception device, a signal having a frequency of 12.5 MHz and including data is transmitted. The data reception device generates a clock B having a frequency of 400 MHz of (1) in FIG. 8, and performs sampling for the above-described 12.5 MHz signal based on the clock B ((2) in FIG. 8). Then, the data reception device detects zero cross points of the sampled data, and generates a 25 MHz frequency clock signal indicating the zero cross points ((3) in FIG. 8). Next, the data reception device generates, by delaying the generated clock signal by the time amount corresponding to eight clocks ((4) in FIG. 8), a 25 MHz signal indicating symbol points. Thus, symbol points can be detected.

Abstract: An evaluation level setting method and a data reception apparatus in which the method is implemented accurately evaluate signal levels in multi-valued transmission for transmitting data while assigning one or more bits of data as one data symbol to a signal level. A data transmission apparatus outputs an initialization pattern signal at turn-on of power or after reset, and the data reception apparatus establishes clock synchronization on the basis of the received initialization pattern signal and starts data reception after setting of evaluation levels to be used for threshold evaluation of signal levels.

Abstract: In the case where transmission and reception is made impossible at a certain portion, a data transmission system configured in a ring LAN performs an initialization process for a physical layer (a transmission/reception section 4) repeatedly, thereby setting as a master a data transmission device which is located most upstream in electrical communication from a disconnection point. With that data transmission device being the master, an initial setting of the physical layer such as a clock synchronization with another data transmission device or the like is established, and an initialization process for a data link layer is performed, whereby subsequent data transmission and reception is enabled. That is, the data transmission system configured in a ring LAN is able to perform communication using transmission lines excluding a damaged point even in the case where transmission and reception is made impossible at a certain portion.

Abstract: A first initialization pattern signal is a signal in which a maximum signal level and a minimum signal level appear alternately, and a second initialization pattern signal is a signal in which all signal levels appear in a predetermined arrangement. In a ring-shaped network including plural stages of data transmission apparatuses (100), a transmission unit (110) of each data transmission apparatus outputs the first initialization pattern signal successively to a next-stage data transmission apparatus at turn-on of power or immediately after reset, and a reception unit (120) establishes clock synchronization on the basis of the first initialization pattern signal received.

Abstract: A signal receiver (11) receives an analog signal via a twisted pair cable (31). An A/D converter (12) converts the analog signal to a digital signal. A phase detection unit (14) detects the phase of the digital signal, and generates a reception timing signal. A transmission timing generation unit (15) controls, based on the reception timing signal, timing for a transmission processing unit (16) to output the digital signal such that the reception signal (point A) and a transmission signal (point D) are different in phase by a predetermined degree. The transmission processing unit (16) outputs, in accordance with the timing, a digital signal obtained by performing mapping on data inputted from a connection device (20). A D/A converter (17) converts the digital signal to an analog signal. A signal transmitter (18) transmits the analog signal via a twisted pair cable (32).

Abstract: A data section is mapped such that the polarity of the signal level of each symbol is constantly inverted on a symbol by symbol basis. On the other hand, a header section is mapped such that the header section includes a distinguishing symbol for distinguishing the data section and the header section from each other, and such that the signal level of the distinguishing symbol is equal to the signal level of the symbol which is mapped immediately before the distinguishing symbol. Thus, data transfer, by which the header section and the data section can be distinguished from each other with certainty by an apparatus on the receiving side, is made possible.

Abstract: A receiver includes a noise reduction circuit for eliminating noise from a differential signal transmitted through a differential transmission line, and a data recovery circuit for recovering data from a differential signal outputted from the noise reduction circuit. The noise reduction circuit includes common-mode chokes for reflecting common-mode noise superimposed on an input differential signal, and a common-mode noise reduction circuit for directing the common-mode noise reflected by the common-mode chokes to a low potential point of the common-mode noise reduction circuit.

Abstract: A control device determines whether an image generated by merging several concurrently picked-up images has consistent image quality on a display device. If determined No, image quality parameters set in each image pickup device are so controlled as to make the image quality of the merged image consistent. Therefore, the merged image can assuredly have consistent image quality. Further, a signal processing device detects, based on positions of nodes and attributes of cameras, a connection indicating which node is connected to which camera and with what attribute. The signal processing device in advance stores every detectable connection and a plurality of image processing programs corresponding to each connection, and selects and carries out one of the image processing programs corresponding to the detected connection.

Abstract: A data transmission device (1) includes a controller (2), a reception section (5), a transmission section (6), and an MPU (3). The reception section (5) receives an electric signal sent from a preceding device, and outputs its data to the controller (2). The transmission section (6) converts a result of a process by the controller (2) into an electric signal and transmits it to a successive device. The MPU (3) controls operation of the controller (2), the reception section (5), and the transmission section (6) in accordance with the operation mode of the device. The reception section (5) detects cessation of the electric signal sent from the preceding device and, in response to the detection, stops operating. In response to the detection, the transmission section (6) stops operating and stops sending the electric signal to the successive device.

Abstract: A cryptographic apparatus reads, from a portable storage medium, content data and cryptographic information specifying a certain part of the content data on which cryptographic processing is to be performed, specifies the certain part in the read content data based on the read cryptographic information, and performs one of encryption and decryption on the certain part. When, for example, the content data is formed from alternating headers and variable-length data sections, the cryptographic information is a program formed from an instruction sequence. The instruction sequence has the cryptographic apparatus detect a header in the content data, read the length of the variable-length data, and perform cryptographic processing on a part of the content data between a start point and an end point, the start point being a position relative to the header position, and the end point being a value resulting from adding the length to the start point.

Abstract: Initialization processes of link layers in a data transmission system are started after initialization processes of respective physical layers are completed. Thus, at the time of initialization of the link layers, the respective physical layers can perform communication with each other. As a result, in the data transmission system in which electrical communication is performed, an initialization program (an API which is supplied assuming that physical layers requiring no initialization process are used) designed assuming that physical layers are in a state where they can perform communication during an initialization period of link layers can be used while satisfying the above assumption.

Abstract: A data transmission system in which normal transmission can be performed irrespectively of the inserting orientation of a connector is provided. A transmitting device transmits to a receiving device a differential transmission signal including polarity decision data for deciding the polarity of the connector. Based on the polarity decision data included in the differential transmission signal transmitted from the transmitting device, the receiving device decides whether the polarity of the connector has been reversed or not. When it is decided that the polarity has not been reversed, the receiving device reads data from the differential transmission signal. When it is decided that the polarity has been reversed, the polarity of the differential transmission signal is reversed for data reading.

Abstract: If a master data transmission apparatus is included in an optical data transmission system, a clock recovered by a first clock recovery unit 91 based on an optical signal received from the optical data transmission system is selected by a clock selecting unit 93. If the master data transmission apparatus is included in an electrical data transmission system, a clock recovered by a second clock recovery unit 92 based on a lock signal received from the electrical data transmission system is selected by the clock selecting unit 93. A mapping unit 74, a digital filter 75, and a D/A converting unit 76 perform processing in accordance with the clock selected by the clock selecting unit 93.