Abstract: A conventional computer is coupled to an analog telephone transmission link by an analog/digital conversion interface adapter. Modem transmission is accomplished by performing the modulation and demodulation functions digitally in the computer's existing processor which executes programs which transfer data between the computer's memory and the interface adapter. Using the same interface adapter and existing processor, the arrangement may be used to send and receive images in the form of standard V.29 format facsimile data, to send and receive data operating as a synchronous IBM 3270 compatible terminal device, or to record and play back conventional voice transmissions rather than data to implement a telephone answering, voice message handling, and telemarketing systems.

Abstract: A full-duplex modem having improved transmission speeds over voice grade telephone circuits that extends the concepts of asymmetric transmission to include echo cancellation techniques. The preferred modem has a high speed forward channel and an overlapping low speed back channel and is capable of transmitting or receiving over either of the channels, depending on the relative data rates. A narrow band echo canceler substantially cancels all or part of reflected transmit signals. Because the echo cancellation technique employed is narrow band, there is a significant reduction in the complexity and computational requirements for the modem.

Abstract: A method of processing incoming digital telephone calls from remotely located call originators which are destined for receipt by a host computer system. The host computer system is linked to the telephone network by a network access server. The call originators may be any type of data terminal, such as a personal computer or a credit card swipe, which is connected to a modem. The network access server extracts control signals imparted onto the telephone line and correlates the control signals with particular communications, routing or applications protocols identified with the call originators. The modem in the network access server which answers the call is configured during the call connect process and placed in a compatible format for the communications protocol of the incoming call. This dynamic custom configuration of the modem reduces the overall telephone call connection and processing time.

Abstract: A method for allowing data communication equipment, such as a facsimile modem, to communicate in a more reliable manner with a facsimile machine. The data communication equipment is interconnected to data terminal equipment, such as a personal computer. The data terminal equipment may include an interrupt driver or controller that only periodically directs the data terminal equipment to retrieve message data from memory and forward it, via a serial port, to the data communication equipment. If the interruption in the transmission of characters to the data communication equipment is too long, no data may be sent to the facsimile machine, which may interpret the absence of data as an indication that the communication link has been disconnected and, thus, abort the call. The method includes the steps of monitoring the message data sent to the data communication equipment for an end of line sequence.

Abstract: Apparatus and method for enabling bilateral transmission of digital data between a local area network and telephone company networks employing both analog and digital telephone lines. A modem modulates signals responsive to signals from a local area network representing an outgoing call to form digital telephone signals suitable for transmission by a telephone line and suitable for demodulation by receiving analog modems. A circuit switched time division multiplex bus transmits the digital telephone signals to the telephone line. The modem also demodulates incoming digital telephone signals to form digital network bus signals divided into packets. A packet bus transmits the digital network bus signals to a network interface which processes the signals and transmits them to the local area network.

Abstract: Techniques for generating a line probing signal. The probing signal is comprised of a plurality of different tones, where the tones have a predetermined phase relationship. The signal may be sent over a communication channel, such as a telephone line. By so using the line probing signal, the non-linearity of the electrical characteristics of the telephone line may be measured with increased accuracy.

Abstract: A construction for an interface between a computer and a transmission medium, such as a telephone line. A memory card may be inserted into the computer and interconnected to an interface module, such as a direct access arrangement, which, in turn, is interconnected to a telephone line. The electronic card and interface module each include a connector for transmitting data signals between each other. Each connector includes two rows of contacts. Each contact in the first row is interconnected to a particular contact in the second row. As a result, the electronic card and interface module cannot be attached to each other "upside down." Further, the electronic card and interface module cooperatively define a latch mechanism for releasably holding the two units together. Further, the two units further define a guide assembly for guiding the contacts of the two units into a correct alignment with one another. The latch mechanism and guide assembly add structural integrity to the construction.

Abstract: Apparatus and method for managing transmission of digital data between a digital telephone line and a computer network. First and second modems, a telephone control circuit and a network control circuit respond to management instruction signals to execute predetermined management objectives and generate management response signals representing one or more conditions of the first and second modems, telephone control circuit and network control circuit. In response to a single packet of management signals from the network, a management circuit generates the management instruction signals and independently addresses them to one or more of the first and second modems, telephone control circuit and network control circuit.

Abstract: A module incorporating flash memory chips. An interface enables power down of the chips in response to a power down signal and provides an interrupt signal indicating when all of the ready lines from the memory chips are in a ready state, thereby reducing the need for polling the status registers in the chips.

Abstract: An improved backplane apparatus for transmitting signals to and from a modem system. The modem system includes more than one modem for transmitting data via at least one telephone line and via at least one network. The modem system has a first bus for management signal communication with the modems at a predetermined first data rate, and a second bus for transmitting data between the telephone line and the modems at a predetermined second data rate greater than the first data rate. The modem system also has a third bus for transmitting data between the modems and the network at a predetermined third data rate greater than the second data rate, and a fourth bus for distributing DC power and ground potential. The modem system defines a first impedance for terminating the first bus, a second impedance for terminating the second bus, and a third impedance for terminating the third bus.

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.