| 摘要 |
PURPOSE:To specify precisely a falut section of a frequency-division multiplex circuit, by converting a multiplex signal of the base band directly and by exercising a supervision in a frequency region in the 1st supergroup. CONSTITUTION:Group supervisory current oscillation part 6 is inserted into the basis group side of group converter 1 and its output is outputted to group converter 4 by way of supergroup conversion parts 2 and 3 and supervised by group supervisory part 7. Switching part 9 changes over respective carrier currents, received from carrier current supply part 8, to be modulated from the 25th supergroup (SG2)-16th supergroup (SG16) to lower group bands and supplies them to conversion part 10 in sequence. Level detection part 12 amplifies fSG1 (supervisory modulated frequency) selected by an extracting filter to a required level and detects and outputs the level to output terminal 13. |
