COHERENT OPTICAL MULTICHANNEL RECEIVER AND ITS CHANNEL SELECTION METHOD

摘要

PURPOSE: To reduce an error of detection data by preventing production of an error clock. CONSTITUTION: A detection means in an out of block state is connected to a band-pass filter 36 or 38, a characteristic of the band-pass filter is changed when the receiver is in an out of block state, a subtractor 30 provides a positive output and a frequency detection characteristic is offset to have a single positive zero crossing by using the positive output. Or the detection means is connected to an offset voltage input Vofs of an AFC loop and when the receiver is restored to a lock state, the offset is automatically released.