Abstract: There is disclosed a conversion circuit arrangement for switching digital data signals between data terminals operating with different data transmission procedures. The circuit arrangement adapted for use with an electronic data switching system is composed of at least two interface circuits having input/output converting networks. External terminals of these interface circuits are connected to respective input/output means of the switching system for each type of data terminal. Internal input/output terminals of the interface circuits are connected to respective terminals of a storage unit. There is provided a control unit for controlling data transmission between the interface circuits and the storage unit and vice versa such that messages are buffered in the storage unit. The stored message is converted according to the data transmission procedure of the receiving data terminal.

Abstract: A circuit arrangement is provided for the transmission of digital signals between transmitting and/or receiving stations which operate with differing data transmission procedures and with different data formats. The signal transmission respectively occurs by way of a converter unit which, like the transmitting and receiving installations, is connected to a switching system. In the train of the transmission of digital signals from a transmitting installation operating with a lower data transmission rate to a receiving installation operating with a higher data transmission rate, the digital signals emitted by the appertaining transmitting installation are first collected in the converter unit in order to be emitted to the appertaining receiving installation only given the existence of a sufficient plurality of such signals.

Abstract: In a teleprinter private branch exchange having a communications unit, to which teleprinter terminals are connected, a central unit and a storage unit, the load due to connections between the individual units on a bus connecting the individual units together is kept as low as possible. For this purpose, the individual units are connected to the bus through the processing systems such that the processing unit of the central unit controls the connection of the processing units of the other two units using the bus for just one signal transmission. It is also provided that the processing unit of the central unit also triggers the execution of the procedures to be executed in the communications unit and supplies the addresses of those storage areas in the storage unit in which associated signals are to be stored or are stored.

Abstract: A distributed processing telex switch having different levels of processor control to handle the calls between terminations connected to the exchange is disclosed. A common control processor occupies the highest level of processor control and function as the system-wide manager. Next below common control is a plurality of master control processors which function to switch the command data between common control and the lower levels of processor control, and to handle the conversation data generated by each of the terminations connected to the exchange. Each master control processor controls a predetermined number of termination from among all of the terminations connected to the exchange. Connected to each master control processor is a plurality of group control processors which control the flow of data to and from a second predetermined number of terminations from among the terminations controlled by each master control processor.

Abstract: There is disclosed a circuit arrangement for receiving unipolar DC signals from a transmission line of a telecommunication system. An opto-coupler circuit is coupled with a light-emitting element at the input side to two wires of the receiving branch of the transmission line. A current reflector circuit arranged at the input side of the opto-coupler circuit is composed of a pair of transistors with a common base connection coupled to one wire of the transmission line. One of these transistors is connected in series by its collector-emitter path with the light-emitting element. The second transistor is symmetrically arranged between both wires of the transmission line. A resistor is arranged in the emitter circuit of one transistor for controlling the current reflection ratio.

Abstract: Apparatus and method for enabling asynchronous, collision-free communication between ports on a local shared bus network which is efficient in the use of bus bandwidth and which, in one embodiment, provides a bounded, guaranteed time to transmission for each port.

Abstract: A circuit for the systematic handling of conversation data from a calling party to a called party for use in a distributed processing telex exchange is disclosed. The customer terminations connected to the exchange are divided into a predetermined number of groups of terminations having a predetermined number of terminations in each group. Associated with each group of terminations is a frame memory which has memory capacity for storing a single bit of conversation data from every termination connected to the exchange. Associated with each frame memory is a vector memory which has a memory location associated with each termination in a group. Each vector memory location contains a frame memory address that addresses the location in frame memory containing the conversation data to be forwarded down to the termination associated with the current vector memory address.

Abstract: A system for generating telex signaling sequences in each termination line in a group of customer termination is disclosed. The system includes a multi-line high-speed line control processor which transmits to and receives from each customer termination, data signals indicative of the signaling levels in the termination lines. The line control processor controls the termination signals by executing, in a time share mode, selected signaling routines for each termination. Connected between the line control processor and the customer terminations is a terminator controller means for selecting the termination currently being time share processed to input to or receive signals from the line control processor. Also connected to the line control processor is a group control processor which supervises the generation of the signaling sequences in each termination by executing script task routines.

Abstract: A plurality of transceivers frequently share a common communication medium or radio frequency channel. A broadcast channel can support only a limited number of transceivers. At some point, the shared channel will become so busy that additional transceivers will divide up more of an already inadequate bandwidth. To reduce the traffic, a broadcast channel is split into separate segments. A segment interface apparatus is used to couple two broadcast segments together. A hierarchical address is employed in the header of each packet transmitted on the medium. The segment interface apparatus compares fields in the header with that of internal registers to determine if the packet should be repeated on the other broadcast segment. An access level within the packet is decremented by the segment interface to control the number of times a packet is repeated.

Abstract: The invention relates to method of interconnecting terminal devices in a digital telephone network wherein either the terminal devices in question normally operate at different data rates or they are to be interconnected over data links in the network which normally operate at different data rates. The method involves firstly determining, by processor means at a switching point in the network, the normal data bit rate of two terminals to be interconnected as well as the normal data bit rate of the or each data link over which the connection is to be made. In the case where there is a difference in the normal data bit rates the processor initiates a procedure to send a digital bit stream to one or both of the terminals to cause the terminals to operate, in the course of the connection, at a common data rate equal to the lowest of the normal data bit rates of said terminals and said data link.

Abstract: Queuing of interexchange messages in a multi-exchange digital telecommunication network is provided using a dynamic store into cells of which the messages are placed. A subsidiary control store has a cell for each cell of the message store and each of these cells contains a control word which contains the status-busy/free of its message cell, plus details of the message including the user for which it is stored when the cell is busy. These details include message priorities, so that queues of messages awaiting attention can be assembled in the store.

Abstract: A conversion structure is provided for converting polarity changes into digital characters and digital characters into polarity changes. The structure includes a conversion circuit which is connected to a termination circuit by way of a memory unit, a communications control unit, and a second termination circuit which operates as an interface. Memory cells are assigned to receive incoming information and transmit the same to the conversion circuit and to receive outgoing information from the conversion circuit and transmit the same to the outgoing side of the termination circuit. The conversion circuit comprises an input code converter, and output code converter and a chain of series/parallel converters and parallel/series converters therebetween. The series/parallel converters receive polarity changes and convert the same into a digital character. Conversely, the parallel/series converters receive complete digital characters in parallel and process the same into a series of polarity changes.

Abstract: An apparatus for connecting a selected one of two teleprinters to a common communication line includes a control unit associated with each teleprinter and an analysis circuit connected to both control units and to the common line through a line interface unit. The analysis circuit can sense an incoming teleprinter selection code and connect the selected teleprinter to the common line. Alternately, the analysis circuit can sense a teleprinter originated communication and connect that teleprinter to the communication line.

Abstract: A terminal unit having a digital autostart circuit for energizing an output device such as a teleprinter. The autostart circuit responds only to the space character which is transmitted between every word in the commonly used Murray and ASCII codes. A method for detecting the presence of information signals encoded in the Murray and ASCII codes wherein a predetermined bit of each incoming signal is inverted and the binary states of each bit of incoming character are sensed to determine the presence of the space character.

Abstract: Signals of different transmission speeds are switched within a program-controlled data exchange system. The exchange system has connection circuits and/or connection circuit groups which are connected to either lines which supply the relevant signals and trunk lines which feed the signals forward. A switching arrangement which receives the signals supplied by the feeder lines to the connection circuits or connection circuit groups emits the signals to the desired truck lines by way of the connection circuits or connection circuit groups in question and carries out switching processes in response to switching requests from the connection circuits or connection circuit groups.

Abstract: Apparatus for establishing multi-address and conference call connections in a switching system comprising line terminators associated with respective incoming and outgoing lines, comprises a connection memory which is common to all line terminators in which there is associated with each line terminator a storage cell which includes, for the duration of a connection, an allocation between a specific calling line terminator and a specific called line terminator. Devices for scanning the line terminators and for addressing the connection memory are included, wherein the line terminators through an evaluation of the address contained in an address storage cell of a connection memory, are interconnected, respectively, only for the purpose of transmitting a message character. In addition to the line terminators for incoming and outgoing lines, additional multi-address terminators are provided.

Abstract: A circuit arrangement for determining specific characters which occur directly consecutively in a sequence of characters, wherein at least one established sequence of characters in a likewise established frequency emits a message signal which can be used to trigger control processes only in the event that characters comprising an established sequence of character elements have occurred in a likewise established frequency directly consecutively in the sequence of characters. The invention is particularly useful in teleprinter exchange systems and is particularly characterized in that the character elements of each character are used to operate a memory which, only when an established sequence of character elements is contained in the relevant character, emits control signals which are characteristic of the sequence of character elements to an evaluation circuit.

Abstract: In order to determine input signals which exceed a given minimum duration, in particular call signals in teleprinter exchanges, upon occurrence of each input signal a counter for executing a counting operation is enabled, the counter output signal occurring upon reaching a given counter position serving the purpose of enabling a logic element via which communication signals (or characters or indicia) are transmitted. If the input signal which has placed the counter into operation is removed in the course of the counting operation, the counter will again return to its initial position. Through these measures, a simple differentiation of input signals having a given minimum duration and of interference pulses, having a shorter duration than the minimum duration, is possible.

Abstract: An electronic transmitter for direct current telegraphy by means of polar line currents has a switching circuit that selectively connects one of the two poles of a telegraphy battery through a unipolar constant current source to a telegraph line, and an output filter having a capacitor in parallel with the telegraph line. The higher frequencies in the telegraphy signals are sufficiently suppressed to keep the noise level in adjacent telephone lines below a prescribed value because the output filter also has two complementary branches in parallel with the telegraph line, at least one of the two branches supplying, in response to a polarity transition of the line current supplied by the current source, a correction pulse having a polarity opposite to the line current to the telegraph line. This output filter is assembled from small-sized, low-priced elements so that an efficient miniaturization of the electronic transmitter in its entirety can be realized.

Abstract: A highly efficient and modular communication network includes a small number of different exchange units including a network controller exchange unit, line master exchange units, line exchange units and terminal exchange units. For high volume, low cost manufacture and ease of maintenance, the exchange units are in turn comprised of a few standard modules such as a microprocessor unit, a RAM unit, a PROM unit and 2 port adapter units. A combination of high communication efficiency and rapid response is attained using small, address carrying data blocks which are threaded through one or more addressable micronodes along a communications channel. A predetermined communication discipline using fixed length blocks and a single start bit per block minimizes data block overhead to maintain a high communication efficiency notwithstanding the small data block size.

Abstract: A micro processor controlled user programmable communications multiplexer subsystem (herein referred to by the symbol PCS) capable of transmitting and receiving data on any one or more of 32 communications lines simultaneously. Each line may be dynamically assigned to a variety of communication characteristics, such as line speeds, character lengths, synchronous, or asynchronous operation, and code structures as well as protocol selections.The system of the invention provides the capability for the user to write his communications programs using novel operations commands that provide code structure and protocol independence as well as communication line independence. Various hardware features and queuing techniques are employed in order to maintain high transmission rates.Variable line scanning in the Teleprocessing Time Division Multiplexer of the PCS is programmably permissible; i.e.

Abstract: A multipoint junction unit at a hub office interconnects a main line and a plurality of branch lines, the main line extending to a control station and the branch lines extending to data station line loops, to downstream local offices and to a main line of a multipoint junction unit in a downstream hub office. Normally, the junction unit broadcasts downstream data to all branches and combines upstream data from the branches for propagation up the main line. When a branch line is to be tested, test equipment connected to the upstream main line sends an address sequence to select an upstream branch and, if required, a second sequence to select a downstream branch, whereupon unselected branches are blocked and the selected branches are unblocked to permit passage of upstream and downstream data. The selected branch may thereafter be removed from the network by a "blocking" sequence which blocks the selected branch and restores all unselected branches.

Abstract: A PBX exchange for teleprinters in which certain protected lines have the facility of direct connection to the main connection lines of the network, when the PBX exchange breaks down. Impermissible connections are avoided during the interruption and during the connection of the PBX exchange to the system by a circuit arrangement responsive to the respective switch on and switch off signals signalling corresponding operations of the exchange.

Abstract: To connect one out of a plurality of peripheral units to a data bus, each unit is connected to two wires of an address matrix. When a unit wants to connect itself to the data bus, it applies a starting voltage to both wires. The central unit then searches in both matrix coordinates for the two wires of the starting-voltage-transmitting unit and connects the unit so found to the data bus by excitation via the wires.

Abstract: A multipoint polling system wherein a multipoint switch selectively connects a plurality of remote terminals to a central station in response to remote terminal addresses transmitted on a signaling path to the multipoint switch. Polling apparatus stores portions of a remote terminal address list provided by the central station and transmits individual ones of the stored remote terminal addresses on to the signaling path. The polling apparatus periodically requests different portions of the remote terminal address list and replaces the stored remote terminal address portion with the requested remote terminal address portion.The multipoint switch is advantageously comprised of a plurality of sections with each section of the switch responsive to a portion of the address list for establishing a signaling path between the central station and selected ones of the remote terminals defined by the address list portions.

Abstract: A method and apparatus are disclosed for using a specified pattern of signal events for signaling in a digital communication system. Illustratively, detection of a first event in a control signal activates timing apparatus which looks for a second event in a control signal within a specified time "window" and at least one additional event in either a data or a control signal within a specified time period. Preferably, the first event is a drop in one of the carrier detect or request to send signals and the second event is a rise in the same signal. The additional event illustratively is reception of two identical data characters, each representing an address and an operation code. Each of these two characters must be received and compared for verification within the specified time period in order to produce an output control signal decoded from the operation code.

Abstract: Apparatus is described for monitoring the state, e.g., with regard to polarity, of signal lines in a telecommunication system. An input circuit, by means of high resistances relative to the line resistance, connects the lines to a differential amplifier having a predetermined threshold of response. A component of the amplifier output is applied to the input so as to have a polarity opposite to that of a bias voltage coupled to the amplifier. A capacitive protective circuit connected between the signal lines provides a time delay thereby protecting against interference pulses.

Abstract: In a digital telecommunication network containing bearer channels between switching nodes, the method of building-up a routing address consisting of routing words that are associated with the switching nodes and via which the transmission of information packets is effected in accordance with the routing address contained in each packet, and for their storage in the region of a called subscriber, dispatching a build-up packet from the first calling subscriber which contains the location-independent call number of the called second subscriber, each switching node retransmitting to other switching nodes connected to it at least the first of several successively received build-up packets having the same call number and whose routing address does not exceed a specific length and adding to each build-up packet retransmitted a routing word associated with the bearer channel connected to it and forming a part of the travel path of the build-up packet, the called subscriber designated by the call number or the switchi

Abstract: A packet switching network in which the data transmitted from a data sending terminal is temporarily stored in a packet switching exchange connected to a data sender where the data is divided into a plurality of units each of which is called a packet and the data in turn is transferred with each packet unit to a packet switching exchange connected to a data receiver, through a number of transmit switching exchanges, and then those packets are reassembled into the original format of the data which finally is transmitted to a data receiving terminal, the above-mentioned packet switching network employing a data sending and receiving system in which a character oriented transmission control procedure for communicating with its associated terminals is used in the packet switching network, and the packet switching network involves data terminals each having a single communication link connected with the packet switching network, whereby the data sending and receiving system is effectively effected and a flow contr

Abstract: A dual-speed, dual format full-duplex two-wire voiceband data transmission system provides automatic speed selection at the answering terminal responsive to a handshaking sequence which is compatible with existing systems operating at telegraph speeds. Existing systems provide asynchronous full-duplex serial data transmission in the speed range of zero to 300 bits per second using frequency-shift keying of tones in split frequency bands dedicated to the respective transmisson directions. Alternative full-duplex serial data transmission at 1200 bits per second using phase-shift keying of carrier waves in these same split frequency bands can now be provided from a common line protocol.

Abstract: A switching system for rapidly configuring transmission paths between comer equipments for high speed digital information in parallel form couples the input of a parallel-to-serial (P/S) converter to the output of each equipment providing information and the output of a serial-to-parallel (S/P) converter to the input of each equipment receiving information. A digital switch rapidly configures information transmission channels between its inputs and outputs in response to instructions from a configuration control. Each switch input is coupled to the output of a P/S converter, and each switch output is coupled through a switch output lead to the input of an S/P converter. A clock provides a periodic clock signal to each P/S converter through an adjustable delay control and to each S/P converter through a clock lead, wherein the electrical lengths of the switch output lead and clock lead coupled to the same S/P converter are equal.

Abstract: A packet-switched digital data communication system operable in a store-and-forward mode is provided for enabling substantially simultaneous full-duplex communication between a plurality of telecommunications terminals, facsimile transceivers or other data input sources over a communications network with a plurality of other terminals, facsimile transceivers or other data sources having access to the communications network and with which such communication is desired. The disclosed packetizing of data and transmission thereof in a store-and-forward mode with dynamic routing provides a highly efficient utilization of the transmission facilities, substantially error-free data transmission and a handshake capability between a wide variety of dissimilar and otherwise incompatible terminal devices such as facsimile transceivers having differing protocols, modulation techniques and other speed and code characteristics.

Abstract: A packet-switched facsimile communication system operable in a store-and-forward mode is provided for enabling substantially simultaneous full-duplex communication between a plurality of telecommunications terminals, such as facsimile transceivers, over a communications network with a plurality of other facsimile transceivers having access to the communications network and with which such communication is desired. The disclosed packetizing of data and transmission thereof in a store-and-forward mode with dynamic routing provides a highly efficient utilization of the transmission facilities, substantially error-free data transmission and a handshake capability between a wide variety of dissimilar and otherwise incompatible facsimile machines having differing protocols, modulation techniques and other speed and code characteristics.

Abstract: Disclosed is a method and apparatus for selectively distributing on a multiple channel television system information previously transmitted and received in the Baudot code. The transmitted information is encoded into a sequence of Baudot characters to include a combination of figure shift and/or letter shift characters which identifies the category or type of information contained in the sequence. Upon receipt, the sequence is decoded to determine the category of information contained therein and then the information is applied to one of a plurality of storage areas in memory, with the particular storage area selected being dependent upon the determination of the information category. After an information sequence has been received, decoded and stored in one of the storage areas, it is then applied to one or more selected channels of the multiple channel television system for display on television receivers tuned to those selected channels.

Abstract: A general digital message network for short address-coded telegrams having plural switching stations. In each switching station the outputs of the input stores are each connected to one of the inputs of a multiplexer. The inputs of the output stores are connected to the output of the multiplexer and the output stores are each connected to a comparator circuit with a fixed value store in which the routing word associated with the outgoing line of the output store is stored, in such a way that upon correspondence of the routing word in one of the fixed value stores with the routing word at a specific location of the address of the telegram in the associated output store, this telegram is transmittable onto the output line thereof.

Abstract: A multipoint synchronous data network is formed by junction units which provide signal paths that interconnect incoming branch lines to a common outgoing branch. The junction units arranged to combine the branches so that data words on one branch are propagated up the common branch, subject to the condition that only one branch can send to the common branch at a time. Each data word includes a designation whether the word carries message information or control information (such as an idle branch condition). Control words are blocked by the junction unit so that message words from a sending branch are not garbled by control words from idle branches.

Abstract: A circuit arrangement for connection of information transducers, which may be compensating networks in program controlled telecommunication exchange systems is described. In the system the transfer of information between the feeder and consumer lines connected to a line connection unit always occurs over a central memory. The storage areas in the central memory, which are connected to feeder lines, can be reached over input code transducers and contain an address datum identifying the desired outgoing or consumer lines. By means of the address datum, the consumer lines can be reached over output code transducers. Compensating networks are connected at the input end to the outputs of the output code transducer and at the output end to inputs of the input code transducer. Applicable outputs of the output code transducer can be reached over an address datum contained in an associated storage area. Specific storage areas connected to applicable inputs of the input code transducer can be reached over these inputs.

Abstract: A method for operating dial-operated telecommunication exchanges equipped with broadcast devices to make conference connections is described. Responsive to signals emitted from a calling subscriber, a conference switching device assigned to the broadcast device is activated; the conference switching device completes the connection in accordance with the switching information contained in the aforementioned signals. The connection is completed as a conventional conference connection in which all participating called subscribers receive all transmitted messages, as a semi-conference connection wherein messages transmitted by each called subscriber are received only by the calling subscriber or as a sub-conference connection wherein messages transmitted by the calling subscriber are received only by a specific called subscriber and messages transmitted by the latter are received only by the calling subscriber.

Abstract: A regulated current pulse is generated for use in transferring digital data from low level voltage devices to those requiring substantially high current such as teletypewriters. By utilizing low voltage components, the current pulse level is continuously controlled, isolated from the low voltage source and applied to the load remotely located.

Abstract: Two facsimile devices, each capable of operating in a plurality of communication modes and having at least one common communication mode are connected together by a telephone line. One of the devices sends to the other a plurality of low and high group frequency signals arranged in a code designating the possible communication modes of the device. The other device receives the signals, determines from them a common communication mode based on its own possible communication modes in accordance with a priority arrangement, and sends high and low group frequency signals to the first device indicating the selected common communication mode so that both of the facsimile devices are set to the selected common communication mode prior to the transmission of graphic information.

Abstract: In a multi-device data transmission system with source and acceptor devices linked by a data highway and handshake lines, provision is made for automatically adjusting the delay of the handshake cycle to suit the highway length and other determinative factors. This is achieved in that the acceptors do not accept data until told so to do via one handshake line, whereas the source is only allowed to issue this command when it has been told via another handshake line that all acceptors have seen the data. The system determines its own delay in this way and automatically adapts the delay to whatever length of highway is employed, whether a fraction of a meter in a circuit board or several tens of meters in inter-rack wiring.

Abstract: A method for indicating the free-line state of a subscriber's line connected to a terminal exchange in a binary data communication system comprising generating and transmitting to the exchange a special code word or byte of a plurality of a fixed number of "0" and "1" bits, such as alternate "0" and "1" bits. This special code word is sent after the closing signal at the end of the communication or traffic, which closing signal comprises a byte of only one "1" bit and nine "0" bits, and before the start-again-of-traffic signal, which start signal comprises a byte of only one "0" bit and nine "1" bits. The special free-line state code signal or byte not only indicates the line is free but also can, by the frequency of its alternate bits, indicate to the exchange terminal its modulation rate so that the subscriber can be automatically connected for the next traffic at this rate.

Abstract: A switched communications system including store and forward facilities is provided in accordance with the teachings of the present invention wherein, in an exemplary embodiment, any of a plurality of teleprinter or teletypewriter peripherals may be given access to the communication system and input information thereto destined for one or more peripherals thereof. Input information from a transmitting peripheral is stored under the control of a central switching system which acts to inspect the destination information associated therewith. If a destination peripheral employing facsimile equipment has been designated, a facsimile controller is enabled and destination information associated with the facsimile peripheral defined is provided thereto from the central switching system.

Abstract: A central station is described which acts as an interface between a two-way communication system superimposed on a power distribution network and a data processing computer. Information from the computer is converted into control signals for activating various sequences of sub-tasks by the communication system. Information from communication system is temporarily stored, converted into a suitable code, and transferred to the data processing computer by way of a teletypewriter terminal. Provision is also made for receiving and responding to priority signals from the system.

Abstract: An asynchronous buffered interface for interconnecting a data processing apparatus adapted to communicate in serially coded ASCII data format and a terminal comprising a printer and a keyboard, both of which are adapted for data communication in parallel format.

Abstract: A data communication terminal with a single data communications means is selectively connected via a first data coupler to a dialed telephone facility or via a second data coupler to a teleprinter facility.