Abstract: Apparatus and method are disclosed for providing a calibrated measurement of signals applied to a local area network cable segment. A remote segment monitor unit has the signal sampling circuit coupled to a signal generating unit. The signal generating unit is controlled by a network system member (node) and applies a series of known signal levels to the signal sampling circuit of the remote segment monitor unit. The known signal levels from the signal generating unit and the signal levels measured by the remote segment monitor as a result of the known signal levels are compared and an appropriate scale factor entered in the processing circuit of the remote segment monitor. Using the calibrated remote segment monitor, the location of network nodes can be identified from the signal levels measured by the remote segment monitor.

Abstract: The disclosed data switching apparatus comprises an input control unit which separates a header from communication data contained in logical channel data, as associative memory which compares the header with incoming logical channel numbers previously registered and which outputs an address control signal associated with an address where any of the incoming logical channel numbers coincident with the header are stored, a temporary storage circuit for outputting, based on the address control circuit, an outgoing logical channel number previously registered and associated with the coincident incoming logical channel number, a communication data buffer for temporarily storing the communication data, and an ouput control unit for combining the outgoing logical channel number from the temporary circuit and the communication data from the communication data buffer and delivering the combination to the outgoing communication channel.

Abstract: An algorithm for ordering selects for a plurality of channels to be multiplexed into a frame is provided. A channel ready counter and a channel select position counter for each of the channels to be multiplexed are initialized. The first and succeeding channel selects are chosen based primarily on the respective values of the channel ready counters such that a channel having a ready counter of relative higher value is always selected before a channel having a ready counter of relative lower value. Where channel ready counter integer values of more than one channel are equal, the select is chosen on the secondary basis of channel rate, with the highest rate channel of the highest ready count contributing first. After a select is made, the ready counter of the selected channel is determined, and the position counters of the channels are decremented by a value corresponding to the number of selects for that channel in the frame.

Abstract: A communication system able to provide multiple path communication between a plurality of stations operating on a single channel. The stations are synchronized and a cyclically repeating series of time slots is defined. One time slot in each cycle is reserved for the transmission of synchronization information by a station designated the master station for reception by the other stations, designated slave stations, and maintaining synchronization therein. Another time slot is reserved for any slave station to transmit a message that it requires to communicate to another station, such indication preferably being by transmitting its own pre-assigned address code. The remaining time slots are used for transmitting address information and data. The slave stations operate in a low power condition except during one of the other time slots when they may receive their own address, or except when they need to transmit data.

Abstract: Provided is a channel status display for an X.25 wide area network (WAN) DTE-DCE interface. The invention, designed for use with a protocol analyzer, monitors X.25 level-2 frame traffic on the DTE-DCE link and produces a dynamic channel-activity-data-structure based upon the level-2 frames. An important class of level-2 frames are so-called I-frames. I-frames contain a 12-bit LCI (Logic Channel Identifier) field. The LCI number identifies up to 4095 channels over which network calls may be transmitted and received at the DTE-DCE interface. The LCI field of an I-frame is used to index an array of pointers. The pointers point to list members in a linked list of call-records. A call-record is a complete listing of call information for a given channel. The array of pointers and the linked list of call-records together make up the channel-activity-data-structure. The data-structure is updated with each new I-frame.

Abstract: Described is a communications system for transmitting baseband and broadband signals simultaneously. The system is ideally suited for interconnecting different types of data terminal equipment (DTE) within a building or limited geographical area. The system includes a backbone communications network formed from a plurality of independent communications systems. Each of the plurality of independent communications systems is dedicated to transmit either the baseband signals or the broadband signals. A Filter Coupler (FC) network combines and separates the two different type of signals at the distribution level. One embodiment of the FC includes a filter network coupled in tandem with a high frequency transformer. In an alternate embodiment the FC includes a balun transformer coupled to a directional coupler transformer.

Abstract: Modems, data service units, application modules and other data communication devices, installed in a common equipment cabinet, are interconnected by way of a time division multiplexed bus. Time slots assigned to the various devices recur at a number of rigidly-spaced access periods across each time division multiplex frame. The rate at which the access periods occur and the total number of access periods that make up each frame are chosen in such a way as to accomodate a mix of devices having respective bus access rates wherein there is at least one pair of rates for which neither rate of the pair is a multiple of the other. The process of allocating access periods to the time slots is carried out using a known lemma to identify linear Diophantine equation solutions.

Abstract: An algorithm for ordering selects for a plurality of channels to be multiplexed into a frame is provided. The channel select position counter for each of the channels to be multiplexed are initialized. The first and succeeding channel selects are chosen based on the lowest price (highest cost) ready channel, with the price of a channel being equal to the value of the channel select position counter divided by the number of selects for that channel in the frame, and the readiness of the channel being indicated either by an indicator, or by the relative value of the position counter to the initial value of the position counter. Where channel prices are equal, the select is chosen on the secondary basis of channel rate, with the highest rate channel contributing first. After a select is made, the position counter of the selected channel is increased by the total number of selects in the frame.

Abstract: In a packet-switched communications network, each of a plurality of terminals sequentially transmits control packets in response to a request for call before sequentially transmitting message packets. A switching node of the network is responsive to the control packets for establishing first and second logical channels through the network. Message packets are propagated through the first logical channel. The established logical channels are monitored to detect an abnormal condition. In the event of an abnormal condition in the first logical channel the message packets are re-routed to the second logical channel.

Abstract: A paging controller for a paging communication system exchanges information by a global multiplexed bus arrangement. The bus arrangement permits voice, data and control information to be exchanged between a common memory and a plurality of I/O modules in a common communication bus. The timing signals of the bus arrangement including the I/O modules are synchronized to expeditiously exchange information among the modules. In operation, each module has a preassigned address representative of a sequence number in a predetermined succession order to permit each module to access the bus.

Abstract: A deman assignment TDMA communication system includes first and second time division multiplexed (TDM) transmitting channels for establishing a broadcast channel from the central station to the terminal stations and a pair of first and second TDM receiving channels for establishing channels from the terminal stations to the central station on an as needed basis. A polling circuit transmits a polling signal on a common time slot of the broadcast channel for polling the terminal stations and periodically shifting the polled station to the next to permit each of the terminal stations to send an acknowledgment to the central station on a common time slot of the established channels. A fault identification circuit is provided for detecting the presence and absence of the acknowledgment at the central station and determining therefrom the location of a fault.

Abstract: A multiplex transmission method using especially a vestigial-sideband amplitude-modulated carrier modulated by a video signal. The method includes modulating a carrier having a quadrature phase with respect to an amplitude-modulated carrier by a multiplex-transmitted signal such as a digital-coded signal with a lower level as compared with the amplitude-modulated carrier, suppressing signal components of a signal obtained by modulating the carrier by a multiplex-transmitted signal, which is located near the carrier frequency, combining the result with the amplitude-modulated carrier, and thereafter transmitting the combined signal.

Abstract: A data communication networking system for carrying messages among a plurality of data handling devices in accordance with a plurality of different networking modes, each device being compatible with at least one of the networking modes, the networking system including networking circuitry for interconnecting the devices effectively in accordance with different ones of the networking modes, and concentrator circuitry having control circuitry for providing signals indicative of the networking modes with which different devices are compatible, and routing circuitry responsive to the control circuitry for routing messages between a given device and the networking circuitry in accordance with one of the networking modes with which the given device is compatible.

Abstract: Methods are provided for multiplexing a plurality of channels on to a sub-aggregate of an aggregate line so as to substantially minimize total frame length. In a preferred method, channel data rates are expressed as a sum of a plurality of predetermined subchannel data rates, and the number of times each predetermined subchannel data rate is used to express a channel data rate of a channel to be multiplexed is accumulated. Given a predetermined primary frame rate (P) such as 8Khz for a DACs compatible multiplexer, and a tertiary frame rate (T) chosen as the greatest common denominator of the subchannel data rates, an optimal secondary frame rate (S) may be found by minimizing for a plurality of different secondary frame rates the sum of (P/S) F1 plus (S/T)F2, where F1 represents the number of calls of the primary frame to the secondary frame, and F2 represents the number of calls of the secondary frame to the tertiary frame.

Abstract: A system for switching signals travelling between a first set of multicontact ports and a second set of multicontact ports, in which the signals at the contacts of each of the first ports are sampled by a parallel-to-serial multiplexer to form a corresponding single serial multiplexed signal. Each such serial multiplexed signal is applied to a matrix switch of the type having a switching device at each cross-point, and each of the output signals from the matrix switch is supplied to a serial-to-parallel demultiplexer. Each such demultiplexer supplies its reconstructed separate parallel signals to its associated port in the second set of ports. By controlling the conduction status of the switching devices in the matrix, the desired connection of each of the first set of ports to the desired one of the second set of ports is accomplished, with many fewer switching devices than would otherwise be required.

Abstract: In order to enable an expansion of a packet switched network and a constitution change thereof to be readily achieved in a multistage switched network constitution, in a packet switched network including a packet data terminal, a packet switching equipment, a PBX, a multiplexer, an LAN, a voice communication apparatus such as a telephone set, and a facsimile or in a linkage between switching modules in a packet switching apparatus, the basic switching modules called configuration units connected to the network are interconnected to each other to form a hierarchic tree structure of which the number of hierarchic levels can be selected depending on a size of the packet switched network. Furthermore, in order to increase the reliability of the packet data transfer in the multi-stage switched network configuration, there are disposed a plurality of connecting lines between bit switches and upper-level configuration units so as to establish a redundant configuration.

Abstract: A sleep-preventing device incorporated within a pair of glasses having a light emitting diode, a photo diode, a buzzer, a power source and a printed circuit board. The printed circuit board is electrically connected to the light emitting diode, the photo diode, the buzzer. The photo diode is lodged in the bridge of the glasses and protrudes from a nosepiece of the glasses. An earpiece of the glasses has a cavity to receive the printed circuit board and the light emitting diode. An opening of the cavity is covered by a plate and a cover on which the printed circuit board is disposed. The plate has a number of holes to receive the light emitting diode, in which bores of the holes are oriented towards the photo diode so that the photo diode receives the light from the light emitting diode.

Abstract: A high capacity metropolitan area network (MAN) is described. Data traffic from users is connected to data concentrators at the edge of the network, and is transmitted over fiber optic data links to a hub where the data is switched. The hub includes a plurality of data switching modules, each having a control means, and each connected to a distributed control space division switch. Advantageously, the data switching modules, whose inputs are connected to the concentrators, perform all checking and routing functions, while the 1024.times.1024 maximum size space division switch, whose outputs are connected to the concentrators, provides a large fan-out distribution network for reaching many concentrators from each data switching module.

Abstract: A high capacity metropolitan area network (MAN) is described. Data traffic from users is connected to data concentrators at the edge of the network, and is transmitted over fiber optic data links to a hub where the data is switched. The hub includes a plurality of data switching modules, each having a control means, and each connected to a distributed control space division switch. Advantageously, the data switching modules, whose inputs are connected to the concentrators, perform all checking and routing functions, while the 1024.times.1024 maximum size space division switch, whose outputs are connected to the concentrators, provides a large fan-out distribution network for reaching many concentrators from each data switching module.

Abstract: A remote maintenance system for a digital communication network, comprises local offices (LOs), at least two of which are grouped and connected to each other by a local line in the group, and a centralized maintenance and operation center (CMOC) located at a tandem office and connected to each LO by an ordinary digital transmission line (DTL) using the No. 7 Common Channel Signaling (CCS) system recommended by the CCITT. When a serious fault, such as system-down, occurs in a first LO in the group, a serious alarm signal is sent from the first LO to the CMOC through the local line, a second LO in the group and the DTL connecting the second LO and the CMOC, so that maintenance data for repairing the serious fault are provided at the CMOC and sent, under the No. 7 CCS system, to the first LO through the DTL toward the first LO.