Research On Algorithm And Realization Of Complete Digital IF And Baseband Transmission System

In this paper, research on the algorithm of complete digital IF and baseband transmission system and the realization of transmitter and receiver.π/4-DQPSK is chosen as digital modulation scheme. The scheme of demodulation is baseband differential detection. Sliding correlator can realize the symbol synchronous acquisition; early-late gate synchronizer is used to do symbol synchronous tracking. Update the software and realize the system of direct sequence spread spectrum. In order to analyze the feasibility of these software arithmetic, Matlab simulation is necessary. Then, the arithmetic can be executed in the hardware. The hardware adopted by this system is the general signal proceeding machine for soft radio. A/D samples the intermediate frequency signal. The digital signal proceeding part based on TigerSHARC dsp can process the baseband digital signal including the algorithm of baseband modulation, baseband differential detection and symbol synchronization, etc. Digital up converter supports interpolation filter and complex mixer. Digital down converter performs down conversion and decimation filtering. The single DSP can transmit baseband signal to digital up converter and receive baseband sample signal from digital down converter through the control of interrupt signal at the same time. The stability and reliability of complete digital transmission system can be realized by this way. The algorithm of baseband digital signal processing are designed with software, so the parameter of system is flexible.According to the above, the system is utility for the research and practicality. In future we can go deep into the research the algorithm of communication based on the technology of software radio.