Abstract: A time-division multiplexing synchronization mechanism employs a 1-bit/frame framing channel with a pattern that repeats every 2 frames. Acquisition and reacquisition of synchronization with such a framing pattern is enabled through the use of an explicit synchronization procedure. With this procedure, initial acquisition of frame synchronization as well as reframing after loss of synchronization are carried out while the transmission channel is carrying only a predefined bit pattern. When the receivers are in synchronization, synchronization is monitored and maintained using a 1-bit/frame framing channel, while the communications link is carrying multiplexed bit streams with the appropriate format.

Abstract: The bit synchronization circuit of the present invention has an extraction circuit for extracting only bits at specified positions from each frame of a data signal comprising a plurality of frames including synchronization detection bits which are set to specified positions of each frame and whose values are different between adjacent frames. It is decided whether synchronization is established or not by a synchronization decision circuit in accordance with values of the bits extracted from adjacent frames among the extracted bits. In the case of the above decision, the bits extracted from the adjacent frames are compared each other among the extracted bits and it is decided that synchronization is established only when the above comparison results do not coincide with each other N times consecutively. Moreover, it is decided that synchronization is not established only when the comparison results do not coincide with each other N times consecutively.

Abstract: An offset circuit (2) detects an offset word serving as a synchronization pattern. By being triggered by the detection, main and subordinate synchronization detection circuits (5 and 6) detect the periodicity of the offset word only during a predetermined backward guard period. Both synchronization detection circuits (5 and 6) detect offset words at different timings. Therefore, if one synchronization detection circuit (5 or 6) fails in detection of synchronization, it is possible to use a detection result of the other synchronization detection circuit (5 or 6). Moreover, received data during the backward guard period is stored in a data memory (11). Therefore, it is possible to use the stored data as received data after detection of synchronization. Even after establishment of synchronization, the synchronization detection circuit (5 or 6) continuously detects the periodicity of an offset word at a timing different from an established timing.

Abstract: A reconnection apparatus in a direct communication system between subsidiary radiotelephone units in which connection between the subsidiary radiotelephone units is forcedly disconnected when direct communication is carried out between the subsidiary radiotelephone units over a prescribed duration of a continuous connection, comprises detection means for detecting the passage of the prescribed duration of a continuous connection and informing the expiration of the prescribed duration of a continuous connection immediately before the prescribed duration of a continuous connection expires; judging means for judging whether there is a communication continuation instruction from the outside in response to the information from the detection means; storing means for storing at least information on the connection destination of the direct communication and information on connection between the subsidiary radiotelephone units when the judging means judges that there is the communication continuation instruction; and

Abstract: The problem of pulse frame synchronization occurs for example in a telecommunications system with cordless terminals operating according to the DECT standard. To establish a radio connection between base station and a cordless terminal, the base station scans its radio cell in sequence with the available ten high-frequency carriers in the DECT frame rhythm. In a multiple cell environment, the synchronization of all base stations belonging to a cordless telecommunications installation is necessary, to enable all base stations to scan the same frequency at the same time. This is achieved by blanking the DECT multi-frame synchronization pulses. The pulse gap is evaluated by error detection circuits which are present anyway, and used for the PSCN Primary receiver Scan Number-synchronization.

Abstract: A central station of a cable television distribution network transmits TDM frames comprising distribution information and overhead information downstream to customer terminals, and determines corresponding upstream TDMA frames by including an upstream frame identity in the overhead information of each downstream frame. Each terminal buffers asynchronous information for upstream transmission, and stores an upstream frame identity which it is assigned. On detecting this frame identity in the downstream overhead information, the terminal transmit a buffer queue size in an assigned time slot of the corresponding upstream frame. The central station uses the queue sizes from the terminals to allocate time slots in the upstream frames to terminals, by including their terminal addresses in the downstream overhead information, for transmission of the buffered asynchronous information. The central station can also assign time slots to the terminals for transmission of isochronous information.

Abstract: A data communication device (500) which is capable of providing inverse multiplexing, avoids having to perform address offset calculations by storing the incoming data from each of its incoming data channels in corresponding data buffers having predefined data structures which eliminate the need for offset calculations during data transfers and protocol processing. The communication device (500) compares the actual address location that a particular byte, such as a frame count byte, is presently stored in the data buffer and the address location it should be stored in order to avoid using offset calculations. If the actual location the frame count (FC) byte is located in is not the desired location the frame count byte should be located, the communication device (500) programs its SCCs (508, 510) to commence storing subsequent data bytes in the appropriate address locations in each of the data buffers found in memory (538) so as to avoid having to perform offset calculations during memory accesses.

Abstract: The invention encompasses a system and method for serially transferring a sequence of data bits having binary values. This includes a step of displaying sequential display frames on a frame-scanning graphics display device, wherein each sequential display frame is associated with an individual group of data bits. Each group of data bits is associated with one or more data framing bits. The framing bits are inverted from one sequential display frame to the next. Within each display frame, sequentially-scanned data transmission lines are selectively illuminated to represent the individual groups of data bits associated with the display frames and their associated data framing bits. Bits having a first binary value are represented by illuminated display frame lines. Bits having a second binary value are represented by non-illuminated display frame lines.

Abstract: A method is provided for detecting a synchronization word in frames of serially transmitted data. The synchronization word consists of l synchronization bits, which are transmitted one bit per frame at a known position in each frame. The method comprises the steps of: storing each incoming bit in a memory organized as groups of words, each having at least l bits, so that each group of words contains bits from a same position in consecutive frames; rotating each group of words; comparing the group of words, at each rotation, to the synchronization word.

Abstract: The invention relates to a signal processing apparatus and a signal processing method. The channel unit of the apparatus includes a plurality of channel data sending units to transmit a plurality of sets of channel data to a multiplexing unit. Part of the channel data sending units are connected to the timing signal line so that channel data from these channel data sending units are inserted into empty slots of the timing signals and are transmitted to the multiplexing unit through the timing signal line. The multiplexing unit of the apparatus includes a channel data separating unit for separating the channel data from the timing signals, and a channel data multiplexing unit for multiplexing the channel data transmitted through the data signal line and the channel data separated by the channel data separating unit. With this structure, data can be superposed on the timing signals used for data insertion and data extraction, thereby greatly increasing the number of channels included in the channel unit.

Abstract: In a time division multiple access point-to-multipoint transmission network, data is transmitted from a central station to local stations in multiframes containing a plurality of frames and a single free period allowing transmit time measurements and reflectometry measurements. Data is transmitted from the local stations to the central station in the form of multiframes containing a plurality of frames and a single free period allowing transmit time measurements and reflectometry measurements, each frame including subframes sent by the local stations, and each local station sending one or more of the subframes contained in a frame. The multiframes are constructed in a way that underuses the data sources, to obtain free periods between the frames, and by time-shifting the frames to construct a single free period per multiframe. Applications include telecommunication networks.

Abstract: A digital communication network has a first end office which includes a first multiplexer unit and a second end office which includes a second multiplexer unit. The network performs transmission and reception of multiplexed signals between the first end office and the second end office. A monitor unit is provided within the first end office. Monitoring is performed of the accuracy of the signal received by the second end office from the first end office, signal accuracy information with regard to the received signal being included as subsignalling information in the input signal Sin which is input to the first end office from the second end office. The subsignalling information is extracted by the monitor unit from the input signal, so as to enable monitoring of the signal accuracy of the input signal. The result is a significant improvement in the improvement of transmission quality monitoring service provided in the digital communication network.

Abstract: A data communication method enables communications between terminals adapted to handle frame structure data having different formats. The terminals are connected via an asynchronous transfer mode (ATM) network in which frame structure data is transmitted in a form of an ATM cell. The terminals include at least a first terminal and a second terminal. The first terminal is adapted to handle data having a super frame (SF) format. The second terminal is adapted to handle data having an extended super frame (ESF) format. A type of frame format of frame structure data to be sent to one of the terminals is distinguished by detecting a synchronization pattern of the frame structure data. The frame structure data is converted when the frame structure data is sent to the one of the terminals so that the converted frame structure data has a type of frame format corresponding to the detected synchronization pattern.

Abstract: Audio data is processed from a packetized data stream carrying digital television information in a succession of fixed length transport packets. Some of the packets contain a presentation time stamp (PTS) indicative of a time for commencing the output of associated audio data. After the audio data stream has been acquired, the detected audio packets are monitored to locate subsequent PTS's for adjusting the timing at which audio data is output, thereby providing proper lip synchronization with associated video. Errors in the audio data are processed in a manner which attempts to maintain synchronization of the audio data stream while masking the errors. In the event that the synchronization condition cannot be maintained, for example in the presence of errors over more than one audio frame, the audio data stream is reacquired while the audio output is concealed.

Abstract: Multi-channel transmission systems make great demands on the adjustment of the local oscillators in order to minimize carrier frequency variations on the transmission and reception sides. There are prior art processes and arrangements in which the local oscillators are adjusted by means of a synchronism word. The prior art processes and arrangements, however, have the drawback that the oscillators cannot be adjusted accurately enough. The present invention overcomes this drawback in that, in addition to the known synchronism symbols, other synchronism symbols are used and the synchronism symbols are evaluated with increased spectral resolution.

Abstract: A superframe lock subsystem includes a correlator which searches for and identifies a first unique word indicative of a frame boundary within a received bit stream during an initial acquisition state. A controller subsequently predicts frame boundaries in accordance with the first unique word. In a tentative frame lock state, the correlator searches for and determines if a second unique word exists at the frame boundary subsequent the frame boundary which corresponds to the first unique word. If the second unique word is determined to exist at the corresponding frame boundary and if a single frame duration separates the first and second unique words, the superframe lock subsystem enters a frame lock state. During the frame lock state, information of the corresponding frames is processed.

Abstract: Apparatus and methods for distributing synchronization throughout a network is disclosed. The distribution of the synchronization is through the use of generating a reference timing signal, and by counting the line clock pulses between the start of a frame and the timing reference signal pulse at a first office and that count is then encoded and transmitted to the next office. At the next office, the transmitted count is decoded and used for regenerating synchronization by counting a number of received line clock pulses from the start of the frame to regenerate the reference timing signal. Particular criteria for selecting the frequencies for the timing reference signal are disclosed.

Abstract: In direct communications between PHS terminals, each terminal detects an intermittent timing signal from a predetermined control channel of the base station. Based on the intermittent timing signal, a terminal intermittently exchanges signaling information with another terminal through an idle channel to establish synchronization therebetween. A calling-party terminal searches for an idle channel and intermittently transmits a control signal to a called-party terminal through the idle channel with intermittently supplying power to a transmitter. A called-party terminal intermittently transmits a response signal to the calling-party terminal through the idle channel. When receiving the response signal from the called-party terminal, synchronization of the calling-party terminal with the called-party terminal is established.