Communication-line-quality measuring system using a conventional signal frame structure

摘要

A communication-line-quality measuring system includes transmission and terminal equipment. Transmission equipment has a first frame assembling part transmitting a down-link multiplexed frame signal to a down-link line having a first frequency, and a first frame disassembling part disassembling an up-link multiplexed frame signal transmitted through an up-link line having a second frequency. Terminal equipment has a second frame disassembling part disassembling the down-link multiplexed frame signal, and a second frame assembling part transmitting the up-link multiplexed frame signal obtained by frame-multiplexing an output signal of the subscriber unit with a control signal, to the up-link line. A pattern generation part in the first frame assembling part provides a test signal to an available channel of signal frames in the down-link multiplexed frame signal. A loop-back part between the second frame disassembling part and the frame assembling part loops back the test signal derived from the down-link multiplexed frame signal in the second frame disassembling part to the second frame assembling part. The second frame assembling part provides the test signal in the up-link multiplexed frame signal to transmit to the transmission equipment. A comparing part in the transmission equipment compares the test signal in the up-link multiplexed frame signal, which is looped back by a control of the loop-back part, with a reference signal the same as the test signal generated in the pattern generation part.