Lucent Technologies Inc.

American Telephone & Telegraph Co., At&t Bell Laboratories

David George Mihal

David A Pierce

Jerry G Miller

Paul R Bufkin

Clifford Royal Johns

Kenneth L Brooks

The present invention is directed to a simulation testbench which includes a circuit under test and a plurality of test models designated through N. The test models include at least one of a driver and a monitor. The drivers selectively apply stimuli to the circuit under test and the monitors observe responses to the stimuli from the circuit under test A single controller is provided for the plurality of test models The controller has an instruction source including a list of commands which control the plurality of test models The commands are routed from the instruction source over a model control bus to the plurality of test models In a preferred embodiment, a common bus interface links each test model to the model control bus and a sequencer addresses the instruction source to put successive commands out on the model control bus where they are accessed via the common bus interfaces associated with the test models for which the commands are intended.

Architecture for simulation testbench control

When a floating battery feed circuit is used to power telephone lines, it is desirable to provide an anti-corrosion biasing circuit to keep the voltage on the tip and ring conductors from becoming positive. This can be done using an anit-corrosion circuit that sinks a dynamic amount of current from the tip conductor. A line circuit including such biasing is, however, incompatible with special lines such as PBX lines that rely on a grounded tip conductor in the talk state. In accordance with the present invention, a constant current is supplied from a ground reference circuit to the ring conductor of such special lines only when loop current is flowing. The magnitude of this supplied current is such that the anti-corrosion circuit holds the tip conductor sufficiently close to ground potential to allow the proper operation of circuits connected to the special lines.

Method and apparatus for providing a ground reference for telephone

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Oswego, IL, United States of America

David George Mihal