Abstract: Non-intrusive performance monitoring of a DS0 channel between a customer premises interface and a D4 channel bank includes an augmentation of existing channel bank equipment and a digital services communication device terminating the DS0 link at the customer site. An auxiliary signalling and performance monitoring arrangement is remotely accessible by a non-resident control site, for example by way of an RS-232 port of a line interface unit of the channel bank, thereby enabling the control site to perform prescribed network supervisory tasks with respect to one or more selected DS0 links, including provisioning of their associated loop equipment and performance monitoring of each DS0 loop. Office channel unit data port and line interface components of the channel bank are modified to provide bidirectional signalling capability via the receive segment of the channel bank's internal communications link.

Abstract: Non-intrusive performance monitoring of a DS0 channel between a customer premises interface and a D4 channel bank includes an augmentation of existing channel bank equipment and a digital services communication device terminating the DS0 link at the customer site. An auxiliary signalling and performance monitoring arrangement is remotely accessible by a non-resident control site, thereby enabling the control site to perform prescribed network supervisory tasks with respect to one or more selected DS0 links. Office channel unit data port and line interface components of the channel bank are modified to provide bidirectional signalling capability via the receive segment of the channel bank's internal communications link.

Abstract: To prevent the occurrence of an anomaly on a single data-sourcing slave channel from causing continuous transmission on that channel and thereby tying up the entirety of a multipoint network, a signal transmission quality monitoring mechanism is incorporated into the office channel unit of each data-sourcing channel. The signal transmission quality monitoring mechanism controls the participation of each monitored digital communications channel on the basis of a measure of the quality of digital signals received from each monitored channel. The control software of each slave channel's office channel unit is configured to include a bipolar violation detector which monitors the channel for the presence of errors exhibited as bipolar violations of alternate mark inversion (AMI)-formatted digital signals. In response to the occurrence of a prescribed number of illegal bipolar violations within a predetermined number of received signals (e.g.

Abstract: The need to equip a digital data service termination with the ability to decode digital loopback commands is obviated by a relatively simple hardware modification of a four wire telephone circuit connecting an office channel unit and customer premises equipment. In addition, the signal processing and test control firmware of the office channel unit equipment (OCU DP) is modified so as to realize a simplified circuit configuration for performing loopback testing of the four wire circuit. The hardware modification of the four wire circuit connecting the office channel unit and the customer premises involves the use of a sealing current-dependent relay circuit that responds to respectively different sealing current flow states: normally; interrupted; and reversed, as converted by the OCU DP. The present invention is particularly useful in subscriber loop circuits that are less than 10,000 feet in length, whereby the need for additional amplifier and noise reduction components is obviated.

Abstract: An all rate equalizer provides direct equalization of a data signal which is automatically adjusted based on data rate and transmission line. The equalizer is embodied in a closed loop circuit in which the amplitude of the data signal is the controlled parameter. The DC amplitude of the data signal is restored by an adjustable gain circuit and the bandwidth of the data signal is restored by an adjustable frequency circuit. The signal processing circuits are adjusted by a control processor in accordance with pre-determined tables of control signals corresponding to frequency and gain values required to provide equalization of the data signal for virtually any given data rate and transmission line. The all rate equalizer thereby automatically provides equalization of the data signal that is optimized for any combination of data rate and transmission.

Abstract: A high-speed modem which acquires receiver operating parameters and equalizer coefficients, stores the parameters and coefficients after an initial modem communication having an initial training sequence, and reinitializes the modem equalizer and receiver at the beginning of subsequent modem transmissions with the previously stored coefficients and parameters to be followed by a shortened training sequence. The modem according to the present invention acquires the above-mentioned parameters and coefficients with improved accuracy by extending the initial training period before the transmission of data. The particular stored receiver parameters include carrier frequency offset and data timing frequency offset parameters. According to the present invention, an additional .DELTA. parameter is determined and stored which optimizes the receiver timing according to a difference between parameters acquired at different portions of the initial training sequence.