Abstract: A digital echo suppression circuit in a four-wire digital telephony circuit having an echo from a local or remote connection to a two-wire circuit or other echo source. The invention incorporates a simple method of using the sample pairs from the first and second sampling circuit to produce a control signal from a control circuit. If the subscriber signal is "louder" than the network signal, then the subscriber signal is passed through. If the network signal is louder than the subscriber signal, the interrupter is activated and a zero level is substituted for the subscriber signal in transmissions toward the network. The invention uses the scheme of comparing instantaneous signal amplitude and using the larger amplitude to set a threshold value. The signal setting the threshold then remains the "loudest" until such time as the other signal can exceed the threshold.

Abstract: A semi-floating AC/DC active termination circuit with current sink. A voice frequency transmission line termination circuit has at least tip and ring terminals and provides an AC termination impedance and a DC termination resistance. The circuit has at least a first resistance element connected between the tip and ring terminate which forms the DC termination resistance. A first resistor/capacitor series circuit, having at least a resistor and capacitor connected in series, is connected between the tip terminals and a first virtual ground terminal, and a second resistor/capacitor series circuit, having at least a resistor and capacitor connected in series, is connected between the ring terminal and a second virtual ground terminal. The first resistance element and the first and second resistor/capacitor series circuits form the AC termination impedance.

Abstract: A modified progressive impedance ladder network has a plurality of cascaded resistive sections. Each of these sectiions has at least one resistive element and a single switch with values selected such that the section input impedance is larger than the output impedance of the preceding section.

Abstract: An announcement and tone generator (10) for use with a telephonic network stores binarily encoded tone samples in a nonvolatile memory (22), such as a PROM or ROM, so that tones are immune to loss of memory due to power loss and, stores the binarily encoded announcements in a volatile memory, such as a DRAM, which is protected against memory loss by means of a back-up battery circuit. A microprocessor (20) provides successive samples of preselected binarily encoded tones or announcements for each of a plurality of time division multiplex channels which are coupled to the telephone network (12) through a digital interface (18).

Abstract: This disclosure depicts an equalizer circuit having input and output terminals and a reference terminal for receiving a reference voltage. The equalizer circuit comprises a first operational amplifier which has a positive input operatively connected to the input terminal and which also has a negative input and an output. A first adjustable resistive means has a first terminal operatively connected to the negative input of the first operational amplifier a second terminal operatively connected to the output of the first operational amplifier has a reference connection operatively connected to the reference terminal and has a third terminal. A second operational amplifier has a positive input operatively connected to the third terminal of the first adjustable resistive means, has a negative input and has an output operatively connected to the output terminal.

Abstract: Digital loop carrier system having CPU to channel unit protocol. A method of communicating with the protocol is used in a telecommunication system having at least a central processing unit (CPU) connected to a plurality of digital interface units (DIU) via a communication module (CM). Each of the digital interface units is connected to a plurality of channel units (CU).

Abstract: The test access system of the present invention is for use in a digital loop carrier communication system having at least first and second terminals connected by a digital transmission line. Each of the first and second terminals has a plurality of analog ports for analog signals and at least one digital port connected to the digital transmission line for digital signals. Each of the first and second terminals also has a plurality of channel units having first ports connected to the analog ports, respectively, and at least one digital interface unit having a first port connected to the channel units and a second port connected to the digital port. The test access system has a channel diagnostic unit connected via a first bus to each of the analog ports and the first ports of the channel units and connected via a second bus to the first port of the digital interface unit.

Abstract: A longitudinal cancellation circuit for use in circuits providing a received differential signal containing a desired differential component and an undesired longitudinal component has a first multiplier for multiplying received differential signal with the longitudinal signal to produce a first signal having at least a DC component in addition to other frequency components. The first signal is received by a low-pass filter which produces a second signal containing only the DC component. A second multiplier multiplies the second signal with the undesired longitudinal signal to produce a third signal equal to the to the undesired longitudinal component. The third signal is subtracted from the received differential signal to produce the desired differential signal which is free of undesired longitudinal component.

Abstract: A packet switching module connects to a multiplexed carrier line which has at least an input line and an output line. A receiver circuit receives an information frame over the multiplexed carrier line. The information frame has a predetermined format which includes a physical destination address. A plurality of processing modules and a controller are connected to a common memory and switching the packets according to the destination addresses. The new information frame is outputted on the multiplexed carrier line by a transmitter circuit.

Abstract: A telephone call distribution system for handling a special type call, the call containing at least automatic number identification (ANI) data, having at least one central switching location for receiving the call and having a circuit for processing, an interfacing circuit with an automatic location identification (ALI) data base having ALI data associated with the ANI data, the circuit for interfacing receiving the ANI data from the processing circuit and returning the ALI data to the processing circuit, and having a storage provision for the ALI data associated with the call; and a connecting circuit for connecting the processing circuit to at least one remotely located terminal for receiving the call, the processing circuit also sending the ALI data to the terminal.

Abstract: A system for allocating a plurality of channel units to a transmission line having a plurality of timeslots including bandwidth and multiple time slot allocation. The system has a counter and a parallel to serial register for providing a channel address via an address signal corresponding to a predetermined one of the plurality of timeslots to each of the channel units. A processor is provided for assigning an assigned address to each channel unit of the plurality of channel units, such channel unit being assigned to a different selected timeslot of the plurality of timeslots. Each of the channel units has a comparator for comparing the channel address in the address signal to the assigned address, the channel unit upon having a correspondence between the channel address and the assigned address, transmitting and receiving on the transmission line. A bus connects the plurality of channel units to the means for addressing.

Abstract: A multi-requester arbitration circuit receives multiple asynchronous request signals and provides a first common timing signal from the request signals. A sample-and-hold circuit receives each of the request signals and produces corresponding output sample signals. The sample-and-hold circuit receives the first common timing signals. A time delay circuit produces a second timing signal from the first common timing signal. A storage circuit receives the output sample signals and produces corresponding output stored signals. The storage circuit receives the second timing signal. An arbitration circuit receives the output stored signals to select one of the request signals and provide at least an output control signal indicative thereof. The sample-and-hold circuit samples each of the request signals before the first common timing signals causes the sample-and-hold circuit to hold all request signals.

Abstract: A system having calls substantially selected and dialed to customers at such a paced rate that the system will keep a group of agents at full occupancy with calls on which the system has detected voice answer. As the size of the agent group changes, this predictive pacing is adjusted so that answered calls do not have to be delayed while waiting for an available agent or agents do not have to wait for calls to become available.

Abstract: A system having a plurality of channel units for connection to a transmission line having a plurality of timeslots. The system has a counter and a parallel to serial register for providing a channel address via an address signal corresponding to a predetermined one of the plurality of timeslots to each of the channel units. A processor is provided for assigning an assigned address to each channel unit of the plurality of channel units, such channel unit being assigned to a different selected timeslot of the plurality of timeslots. Each of the channel units has a comparator for comparing the channel address in the address signal to the assigned address, the channel unit upon having a correspondence between the channel address and the assigned address, transmitting and receiving on the transmission line. A bus connects the plurality of channel units to the means for addressing. An active channel unit has the ability to request communication with the processor by an interrupt signal.

Abstract: An electronic shelf assembly for holding a plurality of electronic modules. The shelf assembly has a first substantially flat, flexible, preformed plastic plate having a plurality of parallel guide channels defined by opposed parallel ribs projecting out of the plane of the first plate. The plate has a predetermined convex contour perpendicular to the guide channels. Small raised extensions in substantially the center of each of the guide channels project out of the plane of the first plate for engaging a recess in at least a first edge of the module, when the module is fully inserted in one of the guide channels. A second substantially flat, flexible, preformed plastic plate has a plurality of parallel guide channels defined by opposed parallel ribs projecting out of the plane of the second plate. The guide channels of the second plate are longitudinally aligned with respective ones of the guide channels of the first plate.

Abstract: A channel redundancy system for use with a central office connected to a remote location. A central office terminal at the central office has a plurality of channel units including at least one spare channel unit. A remote terminal at the remote location also has a plurality of channel units including at least one spare channel unit. The channel units in the remote terminal are correspondingly associated with the channel units in the central office termimal. From a repair service bureau located remote from both the central office and the remote location in a defective channel unit can be identified and replaced by the spare channel unit.

Abstract: A fail safe voice system and method for digital telephone networks. The system provides for operation of voice telephone equipment at a customer location when a fault occurs at the customer location. The system has a central office with an analog line termination/digital transceiver connected to subscriber loop lines. The customer location has a digital transceiver/analog station set interface connected to the subscriber loop lines and to the voice telephone equipment. In response to a fault at the customer location the voice telephone equipment is connected directly to the subscriber loop lines thereby eliminating the digital transceiver/analog station set interface.

Abstract: A circuit is provided for detecting out of range or specification voltages of a power supply output and for disabling the power supply in response thereto. Disabling of the power supply is effected in time delay fashion and a signal is generated to indicate impending disabling of the power supply. The signal may be used to trigger dumping of logic circuit information to registers pending shutdown of the power supply.

Abstract: A method for selecting feedback constants for two echo cancellers in an adaptive 2-wire to 2-wire repeater. The repeater is connected to two networks and when signals are received from both networks, the signal having the greater energy level is identified. A feedback constant of the echo canceller associated with the greater signal is set independent of the feedback constant of the other echo canceller. The feedback constant of the other echo canceller is set as a function of a ratio of the signal energy level of a lesser of to larger of the two signals received from the networks.

Abstract: An answer detector receives first and second control signals from an automatic calling distribution system. The first and second control signals are latched for further use by the answer detector. An address decode circuit receives address signals from the automatic calling distribution system. Furthermore, a pulse code modulated (PCM) data stream and a clock signal is received from the automatic calling distribution system. The PCM data stream is converted from a serial format to a parallel format and held in a data latch.A processor in the answer detector in response to the first and second control signals monitors the PCM data stream for tone and voice energy. Through this analysis made by the processor, the answer detector responds to any of seven conditions: ringback tone, voice, tritone, busy tone, reorder tone, dial tone and a no response status.