Abstract: Embodiments of the present invention provide communication of Asynchronous Transfer Mode (ATM) data using variable duration ATM frames between a data terminal unit (DTU) at a central office and a remote DTU at a user premises. One embodiment of the present invention can be viewed as a communication device which communicates data in an asynchronous transfer mode (ATM) format, the device comprising at least one buffer configured to receive data from a sending device, and a modulation unit coupled to the buffer and configured to encapsulate a plurality of ATM cells into an ATM frame, the plurality of ATM cells having the received data, so that the ATM frame is communicated onto a subscriber line, such that the communicated ATM frame has a variable transmission duration, the variable transmission duration corresponding to a number of the plurality of ATM cells encapsulated into the ATM frame.

Abstract: The present invention provides a method and apparatus for performing a multipoint polling protocol which employs silence intervals for controlling operation of the multipoint circuit. When a tributary station which has no data to send is polled by a control device, the tributary station does not send any signal in response to the poll. The control device measures the time which has lapsed since the last poll was sent and compares it to a “no-data” silent threshold timing interval. When the elapsed silent time exceeds the threshold interval, the control device assumes that the tributary has no data to send and immediately sends the next message. If the beginning of a non-silent response is detected before the threshold interval has passed, the control device receives the response and processes the response in the normal manner, e.g., in the manner in which typical multipoint polling protocols process responses.

Abstract: A protocol allows a device connected to a common channel to communicate directly with another device on that channel during a predetermined slot time. The protocol is particularly suited to a communications network where all communications devices are able to communicate directly with each other. In architecture, the protocol can be implemented in hardware, software or a combination thereof, and is more particularly implemented as follows. A central communications device for processing slot time sequence information and communicating it to tributary communications devices is connected via any number of communications channels to a plurality of tributary communications devices. The configuration of the system is such that the communications devices can directly transmit and receive information from each other. The central communications device optimizes system bandwidth usage by dynamically allocating a sequence of slot times for use in the protocol.

Abstract: A protocol allows a device connected to a common channel to communicate directly with another device on that channel during a predetermined slot time. The protocol is particularly suited to a communications network where all communications devices are able to communicate directly with each other. In architecture, the protocol can be implemented in hardware, software or a combination thereof, and is more particularly implemented as follows. A central communications device for processing slot time sequence information and communicating it to tributary communications devices is connected via any number of communications channels to a plurality of tributary communications devices. The configuration of the system is such that the communications devices can directly transmit and receive information from each other. The central communications device optimizes system bandwidth usage by dynamically allocating a sequence of slot times for use in the protocol.

Abstract: A multi-media modem is used to provide a security access arrangement that identifies a calling party to a computer system. In particular, a multi-media modem couples both an analog channel and a data channel to the computer system. The analog channel conveys the calling party's identification information, while the data channel conveys a data signal from the calling party. The computer system verifies the calling party's identification information communicated over the analog channel and, if the verification is successful, immediately establishes, or continues, data communications with the calling party over the data channel.

Abstract: A simultaneous voice and data (SVD) modem includes two analog ports and a data terminal port. Both of these analog ports are capable of transmitting telephone numbers and are coupled to a switching system like a private branch exchange (PBX). The data terminal port is coupled to a data terminal of an SVD user. In one embodiment of the invention, the SVD user, the calling party, sends at least one command to the SVD modem, via the data terminal port. In response, the SVD modem separately transmits, to the PBX, the calling party number from one of the analog ports and the called party number from the remaining analog port. The SVD modem then subsequently communicates any voice signals received on one of the analog ports to the other analog port. This allows a voice call to be switched through the SVD modem, yet requires no modification to the PBX.

Abstract: A data communications equipment, e.g., a modem, uses a telephone number of a remote endpoint to retrieve an associated set of stored configuration parameters. These stored configuration parameters allow the modem to quickly initialize itself and thereby significantly reduce the training interval with the remote modem. In addition, the use of the telephone number of the remote endpoint allows quick identification of modulation format, e.g., that a fax call is being established.

Abstract: A method and apparatus for control of concurrent communication of analog information and digital information. In general terms, when the communication channel is viewed as a multi-dimensional space, the digital information signal is divided into symbols, and the symbols are mapped onto the signal space with a preset distance between them. The analog signal, generally limited in magnitude to less than half the distance separating the symbols, is converted to component signals and added (i.e., vector addition) to the symbols. The sum signal is then transmitted to the receiver where the symbols are detected and subtracted from the received signal to yield the analog signal components. The transmitted analog signal is recreated from those components. Both half-duplex and full-duplex operation is available in accordance with this invention. The illustrative embodiment includes a controller that is sensitive to input signals applied to the modem disclosed herein.

Abstract: In a simultaneous voice and data communication system, a stream of signal points is partitioned into a plurality of symbol blocks, each symbol block including a data segment and a control segment. The data segment carries information from a user, i.e., user data, while the control segment provides control information. A voice signal is then added to at least a portion, or all, of the signal points of each symbol block to provide for simultaneous voice and data transmission to an opposite endpoint. The control information may represent information from a secondary data source, and/or may include information about the characteristics of the succeeding block, e.g., the user data rate, and information pertaining to characteristics of the communications channel.

Abstract: A simultaneous voice and data modem performs "voice-activated" data rate changes to improve the transmission quality of the voice signal. In particular, when the simultaneous voice and data modem detects that a local telephone set has gone "off-hook," the simultaneous voice and data modem selects a signal space with a lower symbol density, which, although resulting in fewer bits per symbol, provides for a higher quality voice transmission.

Abstract: A modem, capable of simultaneously coupling voice and data signals, connects local digital terminal equipment (DTE) and a local telephone to a communications link. To prevent the local DTE from responding to a communications containing only voice signals, the local DTE is notified of an incoming communication only after detection of calling tone signals on the communications link. Such signals indicate a remote DTE desires to establish a data communications path with the local DTE. This operation advantageously prevents the modem from transmitting an annoying answer tone to a calling party.

Abstract: A local communication apparatus (e.g., a modem) is arranged to detect when a remote communication apparatus desires to switch from the data mode and enter a command/control mode. To accomplish mode switching, the remote apparatus sends a scrambled escape pattern, scrambled using a proprietary polynomial, over the data channel. After detecting the escape pattern the local apparatus switches to the command/control mode. In this mode, the remote and local apparatuses communicate using the proprietary scrambler/descrambler polynomial.

Abstract: In the public switched telephone network, an originating modem can identify an answering modem, e.g., as to the type of modem it is, by detection of a low-level identification signal sent from the answering modem. The low-level identification signal is hidden within an industry standard "answer tone," e.g., a CCITT V.25 answer tone of 2100 Hz. If the low-level identification signal is detected by the originating modem, the industry standard "handshaking" procedure is terminated and a non-standard handshaking procedure is implemented. If the identification signal is not detected by the originating modem, the industry standard handshaking procedure is simply completed.

Abstract: A system and method for reducing the probability of deadlock conditions caused by the repeated transmission of data frames containing data sequences equivalent to those used by serial data communications equipment for inter-device signalling uses a technique wherein a link data input is scrambled for transmission over a channel. The system comprises a commonly used scrambler modified so that a selector is placed in the path of the scrambled data which is to be transmitted and fed back to a shift register. The selector also can select unscrambled generated signalling patterns for transmission through the channel. At the remote end of the channel, a receiver circuit comprises a commonly used self-synchronizing descrambler for reproducing the unscrambled link data at the output. The receiver circuit also comprises signalling pattern detectors for detecting the unscrambled signalling patterns. Patterns are generated at the transmitter and sent to the channels by the selector.

Abstract: In an encryption system comprising DES in a cipher feedback mode of k bits, a plain text bit stream is fed into n individual DES encryptors. The DES encryptor operates in parallel from a common input register containing cipher text bit streams so that the overall throughput of the system is increased approximately by a factor of n. If k=1 then the system is self-synchronizing.