| 摘要 |
PURPOSE:To simplify IC implementation by providing a method which applies a pulse digital signal to a decoder, method which applies the output analog signal of the decoder to a coder for a short time, and method which analyzes the output digital signal of the coder to the supervisory equipment composed of the A/D-converting coder and D/A-converting decoder. CONSTITUTION:An input analog signal and digiyal signal are cut off temporarily by switch 21 and coupled circuit 24 and then, a path is constituted which allows a supervisory signal to flow in a short time, thereby checking the system. This path is composed of supervisory signa generator 25, coupled circuit 24, D/A-converting decoder 15, filter 17, and switch 22 in sequence. In addition, another path is also constituted which is fomed of switch 22, switch 21, filter 10, A/D-converting coder 12, separator circuit 23, and receiver circuit of the coder and decoder fast and the supervision of a low-reliabiliyy circuit such as an active filter is also made possible. |
