Digital signal processing apparatus and an optical transceiver

A light transmission applications without changing the configuration or topology can be selectively utilized to reduce the number of ports of the frame processing unit connected to the digital signal processor. A signal processing unit 6a, 6b includes a modem at a low speed modulation method, a digital signal can be processed by switching the modem selectively in high-speed modulation scheme. Output interface unit A, parallel side interface B is electrically connected to the signal processing unit 6a. Serial-side interface of the output interface section B is electrically connected to the serial side interface of the output interface section D. Selector 7, when the low-speed modulation method is selected by connecting the parallel side interface and a signal processing unit 6b of the output interface section C, the output interface portion C in the case of high-speed modulation method is selected connecting the parallel side interface and the parallel side interface of the output interface section D. .FIELD 1