Abstract: A Scalable Multimedia Network providing integrated networking of data, voice, video and image services over a variety of access facilities including metallic loops, fiber/coax or digital fiber is disclosed herein.The SMN establishes customer initiated switched virtual circuits for all traffic types and directs them to the appropriate backbone network. The SMN is based on a distributed switching platform that enables carriers to economically provide service to a small number of customers and add capacity incrementally as the customer base increases. The platform has a protocol adaptation capability which permits communications between customer premises equipment and potentially incompatible backbone networks or network servers.

Abstract: Loop Performance Monitoring (LPM) for DDS loops is described. Even though DDS loops have Intentional Bipolar Violations (BPVs), a Loop Coding Violations (LCVs) detection strategy based on further processing of BPVs is described. By monitoring LCVs a local loop terminating device can determine Bit Error Rate (BER).A system is described by which an Office Channel Unit (OCU) can process LCV information to determine signal quality of the signal over the incoming local loop. If the signal quality falls below a certain threshold, the OCU can cut the loop off from the DDS circuit and send control codes into the network.A system is also described where a Network Interface Unit (NIU) with the LPM system communicates incoming LCV information to the OCU using low speed signalling over the simplex path between the transmit and receive pairs. The OCU monitors incoming LCVs as well, and thus has the information necessary to determine bi-directional BER performance.

Abstract: Loop Performance Monitoring (LPM) for DDS loops is described. Even though DDS loops have Intentional Bipolar Violations (BPVs), a Loop Coding Violations (LCVs) detection strategy based on further processing of BPVs is described. By monitoring LCVs a local loop terminating device can determine Bit Error Rate (BER).A system is described by which an Office Channel Unit (OCU) can process LCV information to determine signal quality of the signal over the incoming local loop. If the signal quality falls below a certain threshold, the OCU can cut the loop off from the DDS circuit and send control codes into the network.A system is also described where a Network Interface Unit (NIU) with the LPM system communicates incoming LCV information to the OCU using low speed signalling over the simplex path between the transmit and receive pairs. The OCU monitors incoming LCVs as well, and thus has the information necessary to determine bi-directional BER performance.

Abstract: An Intelligent Channel Unit for interfacing end user stations to a DDS digital data communications network and for processing network and end user data according to digital data communications applications is described. The ICU comprises data processing circuitry consisting of a programmable processing circuitry (PPC), a microprocessor controller, and a memory device; a bypass circuit; three input/output data ports; and interface units for the control, maintenance, and test functions.

Abstract: A port concentrator communication system which allows a large number of end user stations to share a limited number of trunk lines to a packet switch network is described. Specifically, the system comprises a number of end user stations each coupled to a port concentration intelligent unit, with these units being coupled together in cascade fashion and the end unit in the cascade being coupled to a set of trunk lines leading to a packet switch network. Each of the trunk line ports corresponds to a channel in the DDS DSOB data streams network and in the reverse direction to the set of end user stations. Special code bytes, indicating the status of trunk line ports, appear in the DSOB data streams and play an integral role in the method whereby the port concentration intelligent units associated with the end user stations can request, obtain access to and communicate over, and relinquish trunk lines.

Abstract: A quadrature coder for a two-wire digital loop communication system is described in which data is sampled and quadrature encoded by being divided into two bit streams, one of which comprises every other bit in the original bit stream and the other one comprises the remaining bits. One of the divided bit streams is delayed by 90.degree. from the other. The delayed and undelayed bit streams are then recombined and transmitted over a two-wire loop.

Abstract: A method and apparatus is described for transmitting and receiving data signals and voice band signals over a single pair of wires, wherein the energy content of the data signals in the voice band is transferred to a higher frequency to avoid interference between the two. This is accomplished by sinusoidally encoding the data pulses in the frequency domain. The encoding is equivalently performed in the time domain by linearly combining weighted delayed and advanced versions of the data pulses, in accordance with a weighting formula. A transversal filter is used to multiple delayed and advanced versions of the data pulses by a scaling factor times the ratio of m!/m-i)!i! factorial wherein i is the ith version being weighted, m is an integer greater than one and ! indicates the factorial function.

Abstract: A method and apparatus is described for transmitting and receiving data signals and voice band signals over a single pair of wires, wherein the energy content of the data signals in the voice bands is transferred to a higher frequency to avoid interference between the two. This is accomplished by sinusoidally encoding the data pulses in the frequency domain. The encoding is equivalently performed in the time domain by linearly combining weighted delayed and advanced versions of the data pulses, in accordance with a weighting formula. A transversal filter is used to multiple delayed and advanced versions of the data pulses by a scaling factor times the ratio of m!/(m-i)!i! factorial wherein i is the ith version being weighted, m is an integer greater than one and ! indicates the factorial function.

Abstract: A post-equalizer and pre-equalizer circuit for use in communicating between nodes in a pulse amplitude modulated digital communication system is described. The post-equalizer circuit comprises a first variable zero circuit, a second variable circuit, and a gain shaper circuit wherein the gain and frequency location of the zeros in the zero circuits combined with the gain of the gain shaping circuit are simultaneously controlled by a control circuit which generates a control voltage which is a monotonically increasing function of cable loss. The control voltage generates a signal equal to the difference between the equalized signal and the original transmitted signal which is used to vary the resistance of voltage variable resistors in the form of FET's in each of the zero circuits and gain shaper circuits.

Abstract: A digital data service transmission system is described in which 19.2 kbps data rate AMI encoded local loop signals are formatted for reliable transmission at 64 kbps rates over unqualified digital facilities and re-formatted for entry into DDS network hierarchy.

Abstract: A post-equalizer and pre-equalizer circuit for use in communicating between nodes in a Pulse Amplitude Modulated (PAM) digital or analog communication system is described. The post-equalizer circuit comprises a first variable zero circuit, a second variable zero circuit, and a gain shaper circuit wherein the gain and frequency location of the zeros in the zero circuits combined with the gain of the gain shaping circuit are simultaneously controlled by a control circuit which generates a control voltage which is a monotonically increasing function of cable loss. In the case of a PAM digital communication system, the control voltage generates a signal equal to the difference between the equalized signal and the original transmitted signal which is used to vary the resistance of voltage variable resistors in the form of FET's in each of the zero circuits and gain shaper circuits.