Optical Wavelength Conversion Unit. STM-64 Transmitting Optical Wavelength Conversion Unit with FEC Function, страница 22

n  Laser transmitting module

Laser transmitting module converts the CMI code flow output from CMI encoding module to optical signals and outputs from the optical port; at the same time, it accepts the control of CPU so as to shut down the laser if necessary. 

n  CPU

CPU collects the status and alarm information of SC1 board and communicates with SCC and OHP through mailbox, and performs such function as A/D conversion, ambient temperature detection, port control (for example: laser shutdown, running indicator flashing, alarm indicator flashing, etc.) and running watchdog to prevent the program from a closed loop.

CPU also provides respective nodes of the system digital flow with clock signals of appropriate phase and frequency through system timing allocation, enabling the device of each node to satisfy the requirements in terms of setup time and holding time for receiving digital signals. It also provides the system with frame indicating signals, which are used to identify the frame head location of the digital flow. CPU board control unit accomplishes the communication with the main control board as well as the direct communication between respective boards. It performs the clock phase lock and service dispatching functions, and generates various other control signals for this board and for the system.  

2. Functions

The functions provided by SC1 board satisfy the requirements of ITU-T recommendations with the features as follows:

n  No restriction on the pump wavelength of the optical amplifier will result from the optical supervisory channel.

n  No restriction on the distance between the two optical line amplifiers will result from the optical supervisory channel.

n  No restriction on the future services of 1310 nm wavelength will result from the optical supervisory channel.

n  The optical supervisory channel is still available when the line amplifier fails.

n  SC1 board is independent from the main control board and orderwire board, that is to say, even if the main control board or the orderwire board is not in position, it can still keep the ECC channel unblocked and ensure the supervision on other stations.

n  SC1 transmission is implemented by sections and with 3R function. At each optical amplifier relay station, the information can be received correctly and new supervisory signals can be added.

3. Application

n  Optical signals of SC1 "RM" input port come from "RM" optical port of SCA board, and the output port "TM" of SC1 is connected to "TM" port of SCA board.

n  SC1 can be inserted in 10~13 board positions of OptiX BWS 320G subrack.

n  The optical connector on SC1 board handle bar is of SC type.

n  SC1 board is usually inserted in the subrack equipped with the multiplexing board.

4. Alarms and performances

Common alarm types of SC1 board are listed in Table 3-18.

Table 3-18 List of SC1 board alarm types