Study On The π/4- DQPSK And DSP

Software defined radio (SDR) technology is put forward in resent years as a new system structure applied to wireless communication. Its basic concept is to implement as many as possible communication functions with software technology on a universal hardware platform. Then, the development of new system and new product are transferred from hardware to software. And the relevant value of wireless communication product depends more on software. From this viewpoint, SDR technology is called the third revolution in wireless communication field followed digital communication and mobile communication.This subject is the signal processing part of SDR system which belongs to a cooperative project----High-speed data transfer access system on monitoring railway security----with a company. The major task is to accomplish a π/4-DQPSK software modem whose bit rate is 36kbps on a ADSP hardware platform. In this paper ,the theory of π/4-DQPSK modem ,such as pulse shaping filter ,differential demodulation and bit synchronization are first introduced. Then author's job is described in detail, including algorithm simulation within MATLAB and the modem system test on a DSP emulator.The following tasks are performed by the author:1.Consulting lots of references and form a full algorithm about π/4-DQPSK software modem.2.Simulating the whole modem algorithm within MATLAB, validating its feasibility.3.Writing assembly program in VISUAL DSP and checking the validity of program.4.Testing the whole modem system on ADSP-21161N EZKIT LITE.