Abstract: A method and apparatus for increasing the capacity of a remote terminal cabinet and providing customer premise service interfaces to the remote cabinet which otherwise has insufficient additional physical slots to support such interfaces is described. The method features removing any protective covering from a space previously designated for but lacking a protection block equipment and installing in the space interface equipment. The installation includes securing the equipment physically in place and connecting the equipment for communications with a distribution service, such as T1 carrier service, at a first interface and a plurality of customer premise service interfaces, such as ISDN BRI interfaces, to customer premises lines at a second interface. The remainder of the remote cabinet communications is left unaffected.

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: An automatic amplifying and equalizing circuit for bipolar data signals has first and second voltage controlled amplifiers controlled by the output of a peak detector. The first amplifier provides even amplification of frequency spectrum components of the data signals while the second amplifier provides amplification of only higher frequency spectrum components of the data signals to compensate for losses of differing length transmission lines. Switches in filtering and frequency dependent circuits provide for operation at several data rates.

Abstract: A digital subscriber loop termination device, such as an office channel unit, dataport unit, digital data bank unit or the like, employs a microprocessor for providing data transfer between customer lines and network lines operating at respective different data transmission rates. The microprocessor circuit responds to network sync pulses for providing transfer of network input bytes to customer output generators and for providing for transfer of customer input bytes to network output serial generators. Additionally, the circuit includes facilities for enabling operation at different customer rates.

Abstract: A circuit for restoring and converting bipolar customer data signals into a pair of binary signals at a customer data frequency equal to or less than 250 KHz includes a PCM integrated circuit repeater for restoring and converting 1.544 MHz communication signals and transmission lines. Use of the high frequency repeater is enabled by a buffer amplifier connected in series with the input of a repeater amplifier and which has an input connected to a parallel resistance and capacitance network which is connected in series with an ALBO diode of the repeater for automatically inserting loss characteristics in the input signal so that the input signal has characteristics resembling losses of a signal passing through a maximum length transmission line. Fixed equalizer and amplification circuitry restores the original pulse signal magnitude and characteristics.

Abstract: A communication bridge joining a primary communication channel to a plurality of secondary communication channels has electrically operated switches in series with the respective ports to the secondary communication channels. Control signals applied to the primary channel are utilized to address the bridge and to selectively drop or add secondary ports. Additionally a loopback circuit can be connected and disconnected in the primary port.

Abstract: DTMF (dual-tone multi-frequency) activated apparatus for remote switching and testing of a four-wire telephone line system is disclosed. The telephone line provides four-wire service between a first location and a plurality of second remote locations. By using a standard twelve button or expanded sixteen button telephone DTMF key pad, the switching and testing apparatus provides the capability at the first location of controlling switching circuits at any one of the remote locations. Each remote switching and testing circuit is provided with a DTMF detector and digital logic responsive to the detector for recognizing an assigned address code and any one of the command codes corresponding to the looped mode, the terminated mode, the milliwatt source mode, and the in-data mode. A programmable three digit address, for example, allows use of up to one thousand switching and testing circuits on one line.

Abstract: Apparatus for remote switching and testing of a four-wire telephone line system is disclosed. The telephone line provides four-wire service between a first location and one or more second remote locations. The switching and testing apparatus provides the capability at the first location of controlling switching circuits at the remote location and making tests of the telephone line system including customer installed equipment. The telephone line, which will include a dedicated transmission path through at least one telephone company central office, is terminated at the respective customer premises by a terminating unit which provides a connection of customer installed equipment to the four-wire line.