APPARATUS FOR TESTING VOICE SIGNAL CIRCUIT HAVING 4 LINES IN FULL ELECTRONIC SWITCHING SYSTEM

摘要

The apparatus is for testing four lines audio signal circuit in whole electronic switching unit, in which the four lines audio signal circuit has one channel composed of two transmitting lines and two receiving lines separated from each other. The testing apparatus includes: a transmitting in-test relay(21); a receiving in-test relay(22); a digital/analog converting part(23); an analog/digital converting part(24); and a testing part(25) for determining whether or not the four lines audio signal circuit is normal by comparing a digital test signal output to the digital/analog converting part(23) with a loop signal which is looped through the digital analog converting part(23), the transmitting in-test relay(21), the receiving in-test relay(22) and the analog/digital converting part(24) in the named order.