| 摘要 |
PURPOSE:To detect the abnormality of a transmitting device, containing a scrambling circuit and a descrambling circuit by adding a known test signal behind a frame synchronizing signal at a transmitting side and scrambling only this test signal. CONSTITUTION:A switch 7 is switched to a test signal generator 9 side by a timer circuit 2, and the known test signal is added behind the frame synchronizing signal. Then, while the frame synchronizing signal is impressed to an EOR gate 10, the scrambling is prohibited and only the added signal is scrambled and outputted to a transmitting terminal 11. At the receiving side, as for the output signal from a register 13, only the frame synchronizing signal is not descrambled and only the scrambled test signal is descrambled. As far as information is correctly transmitted and restored, the signal of logical '0' is outputted from an abnormality detection circuit 18. Thus, the abnormality of the transmission system, containing the scrambling means and the descrambling means can be detected. |
