| 摘要 |
PURPOSE:To switch a status of circuit quality at a high speed against supervisory L deterioration by transmitting preamble burst adding test burst in the transmitting station side and modulating the test burst in the receiving station side. CONSTITUTION:In the transmitting station side, preamble generator 11 generates preamble burst and scrambler 12 generates test burst; ''OR'' circuit 13 composes both of the output, modulates the test burst according to PSK and transmits the modulated burst through satellite circuit 15. On the other hand, the receiving device demodulates 16 the test burst of the received wave according to PSK, detects 17 the preamble burst and descrambles 18 it; exclusive ''OR'' circuit 19 compares the descrambler output with PSK demodulation output and error counter 21 counts a disagreement error pulse. When a counted value exceeds the threshold, an alarm will be generated. Thus, the status of quality of circuit can be supervised and the circuit can be switched at a high speed against the deterioration of quality of circuit. |
