Tie/communications, Inc.

Chestel, Inc.

Alan Bloch

David L Joslow

Frank A Coviello

Candido Puebla

Harold M Straube

Ira Guzik

Chansak Laoteppitaks

Lincoln Henthorn

Charles B Falconer

Each of the station sets in the system generates a continuous, current-modulated digital data stream carrying information concerning the status of pushbutton-actuated switches associated with a particular service or feature. This data stream is transmitted via a phantom pair over standard four-wire cable to an associated station card in the key service unit, which receives and decodes the data, implements any service requested at the associated station set by closure of a pushbutton-actuated switch in the station set, and generates a continuous voltage-modulated digital data stream carrying instructions for the connection of the station set speakerphone to either the first or second talk path formed by the first and second conductor pairs in the standard four-wire cable, for energization of light-emitting diodes associated with the pushbutton-actuated switches in the station set, and for controlling background music transmission to the associated station set. This data stream is transmitted via the aforementioned phantom pair to the station set, which receives and decodes the data and carries out the instructions contained therein. Each station card and each station set incorporates a stored-program digital microcomputer for decoding the received data and for generating the data to be transmitted. Each station card also includes a series of crosspoints in the form of field-effect transistors, the gate electrodes of which are connected to crosspoint latches controlled by the microcomputer. Each crosspoint has an associated input terminal in a status multiplexer which receives data from the passive port to which the associated crosspoint is connected. Each crosspoint and its associated status multiplexer input terminal constitute an active port. Each station card also includes at least one passive port for hotline connection to an active port of another station card or cards, and may also include a passive port for connection to the active ports of one or more link cards. Other system component circuits are disposed on line cards having a single passive port, an internal conference card having a single passive port, a page card having multiple passive ports, a register card or cards connected to the link card or cards, and a tone generator card.

Electronic key telephone systems

The disclosure relates to a four conductor circuit arrangement providing two communication channels between a control unit and a terminal device. Power feed and bi-directional signalling are accomplished simultaneously over the same four conductors used for the two commmunication channels without interference. The signalling from the control unit to the terminal is accomplished by means of a voltage modulator circuit in the control unit by which voltage pulses are transmitted via a phantom circuit arrangement over the four conductors to the terminal unit. The voltage pulses are sensed from the phantom circuit in a data receiver which is located at the terminal unit. Connected to the phantom circuit in the terminal unit is a voltage regulator circuit which receives power from the control unit via the four conductor phantom circuit interconnecting the control unit and the terminal. In series with the voltage regulator circuit is a constant current sink and an inductor. A current modulator circuit is provided in parallel for impressing current data pulses generated in the terminal onto the phantom circuit, which are, in turn, received by a receiver circuit in the control unit. A preferred data format is disclosed as a method for transmitting information between the control unit and the terminal. The preferred embodiment for the disclosed four conductor communication circuit and the disclosed data format is in a key telephone system in which the control unit is a station card in a key service unit and the terminal is a key telephone station set.

Communication circuit with combined power feed and data transmission

A communication switching system of PABX uses a number of time division multiplexed send and receive highway pairs each servicing a plurality of peripheral devices or ports providing two-way communication with the outside world by means of associated telephones, trunk line interfaces, or similar apparatus. All highway pairs are multiplexed in accordance with the same time division format and the maximum number of two-way peripheral devices serviced by each highway pair is dependent on the number of time slots of the format assigned for audio communication. Each peripheral device transmits on a given audio time slot of its send highway. Switching to establish communication paths between peripheral devices is achieved in part by receiving means in each peripheral device responsive to command signals transmitted on command time slots on the associated receive highway instructing each peripheral device on which audio time slots of its receive highway to receive. A further part of the switching is provided by a plurality of highway switches in the common equipment which, under processor control, may forward the signal appearing in any given audio time slot of a send highway to the corresponding audio time slot of any selected one or more of the receive highways, thereby allowing each peripheral device to transmit an audio message to any other peripheral device of the system. Slot shifters are provided and used in cases where a peripheral device attempts to transmit to an audio time slot of a receive highway already in use. A central processor which communicates directly only with equipment in the common control formulates the command messages sent to the peripheral devices over the receive highways, formulates instructions controlling operation of the highway switches and otherwise supervises the functioning of the system. The arrangement of the system is one whereby it may be readily made up of whatever minimum number of highways pairs is necessary to yield the number of peripheral devices or ports necessary to suit the requirements of the office, plant or other facilities in which the system is to be installed, and whereby the capacity of the system, after installation, may be easily incrementally increased by adding additional highway pairs.

Muliple highway time division multiplexed PABX communication system

A processor controlled communication switching system or PABX uses time division multiplexing with pulse width modulation of audio signals. Switching to establish communication paths between peripheral devices serviced by the system is distributed among the peripheral devices and controlled by command signals issued to the peripheral devices by a processor implemented common control. All peripheral devices transmit to the common control on a communication send line and receive signals from the common control on a communication receive line. The particular illustrated system services up to fifty two-way peripheral device ports and is inherently nonblocking.

Time division multiplexed PABX communication switching system

A private automatic branch exchange (PABX) telephone system includes a number of stations connected to a transmission cable by appliques. By digital messages sent over a communication line in the cable, in signalling and supervision time slots, the appliques communicate with one another to make and break talking path connections between stations, which talking path connections utilize other time slots of the communication line, and to perform other signalling and supervision functions. A system clock broadcasts timing signals to the appliques over a timing line in the cable, separate from the communication line, to synchronize the operation of the appliques and to define the time slots into which the usage of the communication line is broken. The system clock also maintains traffic on the communication line by detecting the end of each signalling and supervision message and by initiating a new message upon the detection of such end of message. The system clock also may repetitively broadcast some signalling and supervision messages of its own over the communication line. Except for these functions performed by the system clock, the system operates substantially entirely through the appliques and no common or central control equipment is required. Any number of appliques may be incorporated into the system, up to its maximum capacity, by merely connecting the appliques to the transmission cable, with each applique being connectable to the cable at any desired point therealong and being capable of being moved from one point to another to change the physical location of stations without interferring with the operation of the system.

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New York, NY, United States of America

Alan Bloch