Remote testing system for electrical circuits

Abstract

An apparatus for remotely testing electrical circuits, such as telephone circuits, includes a stand-alone unit which is located in the end office, for example, for remote access by use of an ordinary push-button telephone set sending dual tone multiple frequency signals. The apparatus has a twin-bus structure wherein one of the busses is an analog bus through which the telephone link is made and over which analog test signals are communicated; the other bus is a digital bus for communicating digital control and data signals with a microcomputer included within the apparatus. Operating between the two busses are suitable interface circuits for receiving the control signals from the telephone set and for communicating the analog test signals to a selected electrical circuit to be tested. The analog test signals are generated by an analog test signal circuit also connected between the analog and digital busses. The microcomputer, connected only to the digital bus, controls the operation of the apparatus in response to dual tone multiple frequency control signals received from the telephone set. Responses from the test are transmitted to the remote site as synthesized speech signals for verbally communicating the results through the telephone set.