The Design For DQPSK Testing System

Optical fiber communication has made a great change to the communication area, becoming an important support in this area. Optical fiber communication has not only high-quality signal transmission, good resistance to electromagnetic interference, confidentiality, but also very wide band transmission, so it could communicate with great capacity. But because of fiber and other devices, the capacity for transmission has been limited when optical fiber communication has developed to a certain stage. Due to the special technique, DQPSK technology could transmit several-way signals in one fiber at the same time which could greatly improve the transmission capacity. So it is a good solution to the transmission capacity of the bottleneck.As the great advantages of DQPSK above, the research of DQPSK transmission developed quite well. This design is DQPSK testing system.This thesis analyze every part of the DQPSK testing system , including the following parts:Firstly DQPSK system was introduced, from QPSK to DQPSK, showing the advantages of DQPSK in transmission.Then the 10G PRBS signal as the transmit signal for the testing system is analyzed, showing the advantages and disadvantages of some ways that could generate 10G PRBS signals, and then explain the way in detail that used in this design, and analyze the way on how to generate PRBS signal both on theory and on implementation.Then introduce the driver board for the RF signals of the modulator. In this thesis, the driver board is introduced in detail, including the hardware, software, how to design and make, the principle of hardware, the procedures for the chip on the board and the remote controlling software made in Labview.Then introduce the DQPSK modulator DC bias control board. The design is based on the board which could already control the MZ modulator, and the new DQPSK modulator DC bias control board is able to control the six DC bias of the DQPSK modulator. This thesis explains the theory and the implementation.Finally, the whole system structures and consequence are discussed.