| 摘要 |
<p>PURPOSE:To test the operation without using a special measuring instrument by connecting the output of a pseudo random pattern generator to the transmission side of a digital subscriber's line terminating circuit and connecting this output to the other input terminal of an exclusive OR circuit whose one input terminal is connected to the output of the reception side. CONSTITUTION:The output of a pseudo random pattern generator 3 is connected to the transmission side, and the output of the reception side is connected to the input terminal of an exclusive OR circuit 4. An error detector 5 is connected to the output of the exclusive OR circuit 4. When a hybrid circuit 1 is out of balance to send a pseudo random pattern, the output of a pseudo random pattern generator 3 is inputted to the error detector 5 as the output of the exclusive OR circuit 4 if an echo canceller 2 is normally operated and the output of an adder 6 is '0'. But if the canceller 2 is not normal, the output of the adder 6 is '1' and the output of the exclusive OR circuit 4 is the inverted pseudo random pattern. Thus, the error rate of operation of the echo canceller 2 is measured.</p> |
