| 摘要 |
PROBLEM TO BE SOLVED: To overcome a defect of a conventional maintenance scheme by receiving a test signal via a transmission medium in existence at a remote position and establishing voice band telephone connection to the remote position accordingly so as to monitor an audio signal. SOLUTION: In order to test the maintainability of a CATV channel 112, a processor 106 commands a tone generator 105 to generate an acoustic test signal. The generated and coded acoustic test signal is modulated into a frequency signal suitable for transmission at a modulator/transmitter 104, transmitted to a subscriber site 101 through the channel 112, and received and demodulated by an acoustic receiver/demodulator 109. The demodulated acoustic test signal is given to a telephone interface(IF) 110. On the other hand, the processor 106 sends a control signal to the IF 107. The IF 107 establishes two- way voice frequency band telephone connection 111 to the IF 110 accordingly. The IF 110 transmits a modulated test signal to the IF 107 via the connection 111. The IF 107 extracts bit pattern information and sends it to a processor 107. When a bit error is detected, its amount is used for an index of a transmission fault through the channel 112. |
