Abstract: Information pathways for communications among personnel, among computers, and between personnel and computers, in a local communication system, including remote communications via leased lines or the public network is described. To a public central office, the present invention appears as a private branch exchange (PBX), served by many trunks, WATS, and "Foreign Exchange" lines, and providing all the standard PBX services; to the remote leased facility, it appears as a standard tie line terminator or, if the remote is another ICS, as a logical tie line terminator for which several logical tie lines are combined into each leased T1 line; to the in-house computer, it provides switched connection to other computers or to terminals at up to 19,200 Baud modulated data, at 32K-Baud for native (internal system) data (including 2K-Baud of forward error correction), or up to several gigabits direct binary transmission (such as the transmission scheme used with NDS and ANR displays, etc.

Abstract: A control method and apparatus for an electronic system having a plurality of functional elements, both intelligent and non-intelligent, interconnected by a plurality of time-division multiplexed serial data links, wherein information is normally conveyed in time slots on the data links. Control information is exchanged between the elements by using one or more of said time slots as control channels for all control information. The format of the control information is compatible with both the intelligent elements and non-intelligent elements. The control information format includes a plurality of bits for providing command data, a plurality of address bits, a valid bit to indicate that the information being transmitted is a valid message, an interrupt bit to signal a microprocessor in an intelligent device to interrupt and service the message, and a parity bit for error checking.

Abstract: A key telephone system for use in PCM telecommunications includes an office line communication units, an extension interface unit, a receiving unit, an extension communication unit, and an information transmitting and receiving unit.

Abstract: A system for the wireless transmission of multiple information signals utilizing digital time division circuits between a base station and a plurality of subscriber stations. The subscriber stations may be fixed or movable. The number of time division circuits is determined by the transmission quality of the signals. The base station is interconnected with an external information network, which may be analog and/or digital. The information signals are selected from the group consisting of voice, data, facsimile, video, computer and instrumentation signals. The modulation level of the signals and the power applied to the system are adjusted in accordance with signal error detection in the system. The system is provided with spatial diversity by using a plurality of antennas selectively spaced from each other to provide relatively high signal reception despite signal fading. The base station operates over a plurality of RF channel pairs.

Abstract: A unique packet format is disclosed including a unique transport word, i.e, header, and a number M of relatively short-fixed length information words. The transport word includes a packet size field indicating the number M of information words in the packet and a field indicating the number of bytes of information in the last word of the packet. Additionally, the transport word includes a field which indicates whether the number M of information words in the packet is greater than zero. If the number of information words is not greater than zero, any user information being transported is in a predetermined field in the transport word. In one example, the size field in the transport word is used to transport the user information when the number of information words is indicated as being zero.

Abstract: A unique packet transport word, i.e., header, format is employed which eliminates the possiblity of particular packet transport words being mistaken for other transport words used in a private network, public network or otherwise. This is realized by employing a unique network reference code word to compute one or more prescribed parity checks over bits in predetermined bit positions of the transport word. The network reference code word is used to specify the sense, i.e., odd or even, of predetermined ones of the parity check bits being computed which form the one or more prescribed parity checks. Individual ones of such network reference code words are assignable to specific private transport users and, thereby, provide transparency of their transport words in the public or other networks.

Abstract: A telephone system uses above voice-band ASK control and supervisory signals which are appended to digitally encoded voice by forcing the least significant bits to a selected level for transmission to the receiving end. At the receiving end, the ASK is regenerated by a circuit including special filter. To eliminate audible noise resulting from the filter action, the ASK signal is applied to a shaping circuit which shapes the leading and trailing ASK envelope into a gradually increasing and decreasing envelope. To detect the proper number of pulses in the signal, a threshold detector is used which follows the envelope, ignoring peaks of low amplitude after peaks of high amplitude.

Abstract: A line-adapter of a communications controller includes, for scanning the teleprocessing lines connected to it, cyclic scanning means FES exchanging information with the lines through a serial bidirectional link on which data and control informations are partitioned into frames and slots. Since both the FES and the serial link work with their own timings, an interface FESA is provided to adapt the FES scanning to the serial link structure. This FESA includes temporary storage means for storing on the one hand, data and control information transmitted from the LICs to the FES (10) through the inbound serial link, and on the other hand, data and control information transmitted from the FES to the LICs through the outbound serial link. The access of the FES, the outbound and inbound serial link to the storage means is time-shared and granted by an arbitration logic, according to the relative priorities of operation of said elements within the line-adapter of the communications controller.

Abstract: A modem for connecting data terminal equipment (DTE) to a remote DTE via a general switched telephone network or leased lines at data rates of 300, 1200 and 2400 bps using standard modulation techniques, and additonally providing virtual full duplex transmission capability at 9600 bps using trellis code modulation (TCM). The high-speed 9600 bps path is implemented by asymmetrical frequency division of the available bandwidth into a high speed, wideband forward channel (9600 bps) and a low speed, narrowband backchannel (300 bps). The high speed transmitting channel is assigned to that modem having the greatest data demand and the direction is dynamically reversed whenever the amount of data awaiting transmission over the low speed channel exceeds a predetermined maximum backlog, provided that a direction reversal has not taken place for at least a specified minimum interval during which use of the forward channel is guaranteed.

Abstract: Packet synchronization is obtained by employing a unique packet transport word including at least one prescribed parity check pattern in conjunction with a packet length indicator. An at least one prescribed parity check is computed over transport word length blocks of bits of an incoming packet and compared to an expected parity check pattern in predetermined bit positions in the incoming block of bits to identify possible transport word candidates. Once a transport word candidate is identified the packet length indicator is used to point to the next transport word candidate. Synchronization is declared upon obtaining a parity match for a subsequent transport word candidate pointed to by the packet length indicator. In a specific embodiment, at least two prescribed parity checks are employed to denote a possible transport word candidate.

Abstract: Communication type identification data and message data are sent to a called (call incoming side) apparatus during a communication path formation operation with a desired destination apparatus through a communication medium. The destination apparatus identifies the identification data, and generates different ringing tones corresponding to communication types. When the destination apparatus receives a message, it simultaneously displays the message. A receiving party can easily discriminate the communication types, and can take appropriate reactions, thus allowing efficient response without requiring unnecessary answering process.

Abstract: A distributed algorithm for clock synchronization in address independent networks such as token rings and token busses is described. Synchronization is accomplished by using the fastest clock in the network as the master clock against which all other clocks in the network are synchronized. An algorithm is implemented in which each node sends out a message to all the other nodes in the network when its timer times out to tell its time. If a node receives a message with a higher clock time before it has had an opportunity to send out its own message, that node assumes that it is not the fastest node and it will not send out its message. Provision is made for maximum and minimum delays that are expected within a particular network. It has been proven that after a few cycles, all nodes will be synchronized to the node with the fastest clock and that this node will be the only one to transmit its time.

Abstract: A method of integrating one or more accessory function modules in telecommunication systems is disclosed, especially digital telephone extension systems, where communication between two user terminals is achieved using time division multiplexing by assigning a pair of time slots through a central exchange, and by preassigning at least one particular time slot which can be accessed to allow communication between the accesory function module or modules and the user terminals.

Abstract: In a wireline data transmission system for passing data between downhole and surface locations in a wellbore, a system for transmitting data at a frequency above the relatively low roll of frequency of a wireline permits higher data rates to be transmitted over the wireline than would be possible using standard digital data formats. The present system utilizes short duration pulses which are placed on the wireline in conformity to the transition edge between voltage levels in a typical digital data format, and thus transmits the digital data over the wireline in a manner which is not adversely affected by the phase shifting which normally occurs when bi-level voltage data formats are used for data transmission over a wireline.

Abstract: A line unit interface circuit used on line units in a line shelf of a digital loop carrier provides all of the logic necessary to access two subscriber lines to a line unit interface bus connected to common equipment within the line shelf. Information received from the common equipment includes signaling data, configuration data and provisioning data, which is reconfigured and processed by the line unit interface circuit for controlling the subscriber line channels. Configuration data from the common equipment is decoded to assign time slots on the line unit interface bus to the various channels serviced by the line shelf and to further provide for a timing offset between the transmit and receive strobes provided to each subscriber line circuit. A flywheel circuit is used to prevent erroneous time slot assignment in the event of noise or interference on the line unit interface bus.

Abstract: A network (A) carries large image blocks among medical diagnostic equipment (20, 22, 24), archive computer (26), and data handling and display stations (28, 30). Four kilobyte packets of 4 megabyte image blocks are moved from transmit buffers (38) to queuing buffers (42). The order in which packets from the queuing buffers are transmitted on the network medium (10) is determined by a combination of an assigned priority, duration in the buffer, and a statistical availability of the addressed receiving node. A data link (52) at the receiving node includes an elasticity buffer (122) which stores a small plurality bits, e.g. 5, to accommodate for variances in the clock speed of the transmitting and receiving nodes. A buffer table (60) monitors memory addresses at which preceding data packets corresponding to the same image are stored and provides address information to send each subsequently received packet.

Abstract: Information pathways for communications among personnel, among computers, and between personnel and computers, in a local communication system, including remote communications via leased lines or the public network is described. To a public central office, the present invention appears as a private branch exchange (PBX), served by many trunks, WATS and "Foreign Exchange" lines, and providing all the standard PBX services; to the remote leased facility, it appears as a standard tie line terminator or, if the remote is another ICS, as a logical tie line terminator for which several logical tie lines are combined into each leased T1 line; to the in-house computer, it provides switched connection to other computers or to terminals at up to 19,200 Baud modulated data, at 32K-Baud for native (internal system) data (including 2K-Baud of forward error correction), or up to several gigabits direct binary transmission (such as the transmission scheme used with NDS and ANR displays, etc.

Abstract: A dual digital signal processor (DSP) provides real time links between multiple time division channels of a digital carrier system (e.g. T-1) and a host data processor. Operating only on digital signals, internally and at its interfaces to the carrier and host systems, the DSP exchanges data and control signalling information with the carrier system and data and control information with the most processor, converting the data in passage to different digital forms. At the interface to the carrier system, signals are received and transmitted in a form adapted to diverse terminal equipment of users remotely linked to the carrier system via the switched public network. At the host interface, signals are transferred and received in a form suited to the data process requirements of the host system (e.g. data bytes directly representing alphanumeric characters). Thus, the DSP acts as the equivalent of multiple different types of modems in performing required conversions.

Abstract: In a digital radio communications system, a mobile station in the service zone of a first base station transmits a reconnect request packet to a second base station when leaving the service zone of the first and entering the service zone of the second during a session with the first base station. The second base station communicates the receipt of the reconnect request packet to the central station, from which a proceed-to-clear command packet is sent to the first base station to allow it clear the connection with the mobile station and return a clear response packet to the central station informing it of a serial number of the last data packet it has received from the mobile station immediately before leaving its service zone. On receiving the clear response packet, the central station sends a reconnect command packet indicating that serial number to the second base station to cause it to issue a reconnect response packet to the mobile station requesting the reconnect.

Abstract: A time-division switching system, in particular a multiservice key telephone or PABX system, is controlled by programmed management logic and synchronized by a timebase for selective on-demand exchange of information between terminations to which telecommunications terminals are connected either directly or through links to other, identical or at least compatible switching systems. The system includes programmed system management logic based on an optionally duplicated processor with directly addressable memory which stores all command operations, in particular those for switching information exchanged by means of the terminations which are connected in parallel to a port of the processor by a bus-type time-division multiplex link.