Abstract: A multiple access communication system with a multi-channel construction and applicable to a local area network (LAN). In a broadband LAN, channel assignment is agreed upon by two nodes which are to hold a communication therebetween so that a channel assigned may be continuously occupied by those nodes. The system makes it possible to perform channel assignment and channel interchange which are based on fully decentralized control. In addition, the system accommodates communications on those traffics which are entirely different in nature from each other, e.g. those in which analog and digital informations are mixed together.

Abstract: In a packet-switched communications network, each of a plurality of node stations is responsive to a request for a circuit-switched call from a source user terminal and transmits a control packet and a message packet in succession to the other node stations. The control packet contains a source address, a destination address, a unique address and a time slot number identifying the time slot in which the circuit-switched call is to be carried. The message packet contains the same unique address as that sent with the preceding control packet and a plurality of time slots identified by the time slot numbers containing in various control packets. On receiving a message packet having the same unique address as that sent with a previous control packet, a destination station extracts an information signal from the message packet using the time slot number contained in the previous control packet and supplies the extracted signal to a user terminal identified by the destination address.

Abstract: The invention provides switching arrangments for use in digital telecommunications exchange systems for local subscriber access and comprises a selector means (PUBS) which is arranged to interface between a plurality of time division multiplex highway groups (G0 to G3) and a plurality of channel digital traffic paths (C0 to C5). The selector means (PUBS) is microprocessor controlled (MCI) to effect a plurality of different switching connectivity modes enabling bothway communication between various combinations of the time division multiplex highway groups and the channel traffic paths when the input and output data rates (1 Mbit/sec, 64 Mbit/sec or 32 Mbit/sec) of the particular connectivity mode is either compatible or incompatible.

Abstract: A data transmission control unit having a function of receiving a token having source address information on a loop transmission line, getting a transmission right, transmitting the information frame and then sending the token to abandon the transmission right, comprises means for determining whether the relay of the token sent by its own unit successed or not based on the time elapsed after the token has been sent, and control means for not transmitting the token when the relay was successful and retransmitting a new token only when the relay was not successful.

Abstract: An analog multiplexer with N variables (or control signals) is provided, the configuration of which is defined by a number of controlled switches in series per channel and per input parameter (or per input) which is equal to K, K being defined by the ratio N/2 or the ratio (N-1)/2 depending on whether N is even or uneven, respectively, and a number of input parameters (or inputs) equal to the number of combinations ##STR1## The N control signals are appropriately assigned to the different switches of each input.

Abstract: A transmultiplexer for use in a telephone system is disclosed. The transmultiplexer includes a programmable virtual distribution frame feature which provides for information traffic to be switched from one digital group facility to another analog facility in both time division multiplexed and frequency division multiplexed directions.

Abstract: Methods and apparatus for exchanging frames between bridges distribute load sharing in a communications network. The communications network is of the kind in which bridges, and related stations and local LANS, e.g. Ethernet LANs and 802 LANs, can be linked by paths in a plurality of sub-networks and wherein the bridges are linked to support a Spanning Tree Protocol (STP) which elects one bridge as a root and then with respect to said root, computes and utilizes one and only one loop-free set of primary paths between all bridges. Remaining paths, i.e. paths other than said STP primary paths, between the bridges are examined as possible sub-network paths for a Distributed Load Sharing (DLS) configuration in which frames exchanged between certain stations can utilize more than the STP one set of primary paths. Certain ones of the remaining paths are selected as DLS paths under certain conditions and frame are routed over a selected DLS path only when those frames meet certain criteria.

Abstract: A time-division multiplex transmission network system applicable to an automotive vehicle in which each data transmission station constituting the whole network system together with data reception stations is activated to transmit a data only when an address (station identification information) allocated thereto coincides with one of the series of information on the specification of a pair of stations between which the data is communicated. Consequently, discharge of a battery whose electric power is distributed into all data transmission and reception stations can remarkably be reduced since other transmission and reception stations are deactivated during the time slot at which the address allocated to the pair of transmission and reception stations coincides with the one information for specifying the data communication stations.

Abstract: A controller for a bridge interconnecting local area networks operates in two modes. In a first mode the controller receives and transmits station data frames with previously appended frame check sums. In a second mode the controller responds to requests for information from stations by generating data frames from an associated memory. The controller computes and appends frame check sums and then transmits the frames and check sums to the requesting station. The controller is constructed and is effective to operate in a way which insures that all station data frames transmitted from stations to the bridge are received by the bridge without interruption or loss during all periods of operation. The controller receives all such frames at all times, including the time intervals during which circuitry in the controller must be off line and reprogrammed for changing operation between the first and second modes.

Abstract: A system in which two stations are respectively provided with telephones and data terminals such that a voice and data are multiplexed for communication between the two stations. Each station has a circuit to convert voice signals inputted from the telephone into a plurality of kinds of predetermined voice parameters, a circuit to determine a transmission mode depending on a predetermined parameter of the voice signals, a circuit to extract data having a length corresponding to the transmission mode from data to be transmitted from the data terminal, a circuit to select one of the plurality of voice parameters depending on the transmission mode, and a unit to edit a mode indicator indicating the transmission mode, the selected voice parameter, and the extracted data into a transmission block format corresponding to the transmission mode.

Abstract: A TDM switching system for providing selected connections between large numbers of lines and trunks and which may combine, in an integrated system, several TDM switching systems which are adapted to handle smaller numbers of lines and trunks so as to expand the capacity of such smaller TDM systems. The system has a distributed, modular architecture in which the lines and trunks are arranged in a plurality of domains. The domains each have a link controller which links the domains to interdomain PCM highways. The domains each include, as the members thereof, a plurality of devices.

Abstract: Digital data networks (such as the ISDN) which provide transmission between selected locations may use time multiplexed slots with predetermined maximum bit-rates. However local area networks (LANs) transmit packets, containing data bits, at a rate which varies frequently and often corresponds to a higher bit-rate than can be handled by individual slots. In the present invention packets arriving at an input port are allocated to a number of queues each for a respective destination, and each queue is allocated a group of slots on a digital data network. The slot contents are assembled into frames in a buffer store and transmitted to the digital network. On reception, the contents of several frames of incoming multiplexed slots are held in a frame store and then assembled into packets in a number of buffers making allowance for arrival in a different slot order and different frames.

Abstract: A channel unit is disclosed for interfacing a digital subscriber line (DS1) to a PCM digital transmission facility, for example, T carrier. The basic rate interface (BRI) 2B+D format is converted to a unique three time slot format for transmission in the DSl PCM signal format. The two communication B channels are interrogated to determine if they have a logical 0 in each bit position, i.e., zero byte. If so, a non all logical 0 bit pattern is substituted and a logical 1 indication bit is inserted in an associated bit position in a control channel. In a receiver, the associated indicator bit positions in the control channel are interrogated to determine if an all logical 0 bit pattern, i.e., a zero byte, had been replaced. If so, an all logical 0 bit pattern is inserted in the associated communication channel. A logical 1 is inserted in bit position 2 of the control channel to negate the possibility of emulating a T carrier yellow alarm condition.

Abstract: A remote segment monitor unit is disclosed that is coupled to a segment cable of a local area network system. The remote segment monitor unit, for each transaction on the cable segment, determines a value related to the transaction signal strength and determines the identity of the network node from which the transaction originated. By providing a record of the transaction signal strength associated with each network node as a function of time, components that are functioning outside of acceptable boundaries, components showing erratic behavior and components with deteriorating performance can be identified.

Abstract: A time-division multiplex transmission network system having a plurality of data processing stations, in which data of a predetermined number of bits is transmitted on a data transmission line for a period of time determined by the number of bits of data by one bit in synchronization with a synchronization signal extracted from a predetermined time series code string signal when one of code patterns derived from the predetermined time series code string signal coincides with a predetermined code pattern indicating an address allocated to one of the individual data stations.

Abstract: A circuit includes shift registers (SR1, SR2, SR3) having different write and read rates under the control of clock pulses of different frequencies so that they form part of a signal compression or signal expansion circuit for encoding from simultaneous signals to the time division multiplex signal and for decoding from the time division multiplex signal to the simultaneous signals, respectively. The circuit is an integrated circuit (IC) having shift registers (SR1, SR2, SR3) suitable for both series-in, parallel-out and parallel-in, series-out operation. The shift register (SR1) with the greatest number of register stages is coupled to parallel connections of at least two further shift registers (SR2, SR3) via a through-connection circuit SC1 for a parallel bi-directional connection of the register stages. The series inputs and series outputs of at least the three shift registers are each coupled to a connection terminal of the integrated circuit (IC).

Abstract: A time base converter employs a two position, phase lock loop (40) to write twice orthogonally spaced signals into a split phase memory (34), which in turn can be read out at the timing rate of an incorporating communications system. The converter effectively converts the time base of signals read out of a demodulator (14) to the system time base, thus permitting use of the demodulator in computer based, digital processing systems. Readout of the signals is facilitated by a pair of marker tones f.sub.H, f.sub.L which are introduced into the signal on the upper and lower sides of the input bandwidth. The signal is digitized by A/D converters (28, 30) and the resulting data is employed to drive the phase lock loop. The phase lock loop includes a counter (44) driven by a voltage controlled oscillator (46) which time shares a pair of loop filters (52, 54) that respectively pass the marker tones f.sub.H, f.sub.L.

Abstract: An echo cancellation arrangement is provided for decreasing the "singing" of a connection of a large number of telephone subscribers in a conference calling arrangement. This arrangement includes a means for inserting quiet code during time when the voice samples of incoming PCM data are zero or below a predetermined minimum threshold level. This helps decrease the amount of feedback which is amplified and output through the codec/filter to the listeners through the PCM network. An attenuation arrangement is also included which decreases the level of a summed signal of a summing node of the conference circuit. This sum signal is the combination of each of the conferees' speech. Attenuation of this signal prohibits excessive coupling of amplified feedback to each of the listening conferees.

Abstract: A serial network architecture is presented which can be used to link user oriented devices together. Network devices are linked together in serial fashion. If data is transmitted serially, an interface between two devices requires only two wires. Additionally, a wire for power and a wire for ground may be added so that each individual network device does not need to have its own power supply.

Abstract: A fast circuit switching system that establishes a circuit for each packet-sized data communication. Information is conveyed from a number of communications modules in source channels to a number of port controllers and to a network. Information is conveyed from the network to destination channels. Each communications module includes a transmitter that transmits in an associated source channel, circuit setup request signals defining destination channels and also transmits data. Each port controller stores one of a number of status words defining the availability of the destination channels and each of these status words is cycled to each port controller. A port controller responds to one of the circuit setup request signals and to subsequent data, when one of the status words cycled thereto defines as available, a destination channel defined by the circuit setup request signal, by transmitting the circuit setup request signal and the subsequent data to the network.