| 摘要 |
<p>Disclosed is a drop/insert selecting system in an optical transmission system. To decrease the circuit scale, the system comprises a switching unit (4, 4') having a plurality of input terminals for receiving a plurality of input channels and a plurality of output terminals, each of the input channels conveying a frame synchronization signal and a channel number; at least one drop/insert unit (51, 52, 51', 52') for sequentially generating channel preselection signals until a frame synchronization is established, and for dropping or inserting necessary signals from or into a corresponding one of the necessary channels incorporated into the drop/insert units when a frame synchronization is established; and a channel selecting unit (6, 6a, 6b) for generating a plurality of channel selecting signals in response to each of the channel preselection signals, each of the channel selecting signals functioning to connect each of the output terminals to one of the plurality of input terminals; the remaining output terminals of the switching unit being connected to through-channels to which no drop/insert means is connected.</p> |
