Abstract: Expanding the number of telecommunication services ports, such as ATM-compatible ports, by linking a master unit comprising a fixed number of ATM-compatible ports with one or more expansion units comprising supplemental ATM-compatible ports. A flexible expansion link can be connected between a pair of expansion units to form a chain of expansion units. The master unit can be connected to the chain of expansion units via a flexible expansion link. This combination of a master unit and one or more linked expansion units provides a scaleable deployment solution for the provisioning of ATM-compatible services to the subscriber base of a service provider. The master unit can send a continuous data stream in the downstream path to the chain of expansion units. The expansion units can synchronize to the framing pattern of the downstream data output by the master unit and extract information intended for a particular expansion unit from the framing pattern.

Abstract: A method and apparatus for effecting a digital communications in a tandem cross-connect of an intermediate station in a telephone system communications network to enable synchronization of the digital signals coupled between ports of the cross-connect. The method and apparatus provide center-tapped transformers at each port for coupling into the cross-connect, applying synchronizing signals to the center-tap of the transformer for raising and lowering the DC voltage of the transformer output cross-connect side without adversely affecting the signals being transmitted across the transformer coupled network, and processing received signals to identify and synchronize to repeating protocol patterns. In particular, the invention employs photo-optically coupling to the transformers to maintain electrical isolation of the synchronizing elements of the circuitry and employing the circuitry in particular in connection with synchronizing to the A and B signalling bits of a T1 protocol.

Abstract: A method and apparatus monitor the performance of a DDS loop connecting an information transmitter to an information receiver. The information transmitter is typically at a customer premises while the receiver is typically an OCU at the receiving local office. The DDS loop uses an alternate mark inversion communications protocol and the monitoring method and apparatus feature circuitry for determining a current imbalance on the DDS loop. The numbers of positive and negative pulses on the line are individually counted and if the count of the two counters used deviates either positively or negatively from each other by specified amounts, an error event is declared. If the error events meet a statistical timing criterion, a channel error is declared and appropriate steps are undertaken to prevent signals coming from the channel from interfering with other signals available at the local office.

Abstract: A PCM rate conversion module is provided for interfacing a thirty-two channel PBX with a twenty-four channel link. The PCM conversion circuitry includes an inbound data memory station and an outbound data memory station wherein inbound T1 data is looped back out to the T1 data link and outbound PBX data is looped back out to the PBX. The looping provides effective and reliable testing of the rate conversion apparatus.