LINE QUALITY DETECTING METHOD AND ITS DEVICE

摘要

PURPOSE:To improve the detecting accuracy of line quality by discriminating a receiving signal to plural levels, obtaining the deciding signal of plural bits and comparing with a deciding signal. CONSTITUTION:The signal of a terminal is decoded by the same error logic as that of the transmitting side by an error correcting decoding circuit 2 and sent to the output. An output is a parallel signal, inputted to an error correcting code circuit 3 and the error correcting coding is executed by the same error correcting logic again. The output of the error correcting code circuit 3 is connected to the input of one side of three comparing circuits 51-53 respectively. On the other hand, the receiving demodulating signal of a terminal 1 is delayed by a delaying circuit 4' and quantized to the signal of three bits at a level deciding circuit 11. Respective outputs of the three quantized bits are connected to other input of the comparing circuits 51-53 respectively.