Design Of QPSK Wireless Transceiver System Based On AD9361

In the field of modern communication technology,there are more and more diversified systems.How to realize the coexistence of multiple systems at the same time is an important topic.The software radio technology with the characteristics of compatibility and easy expansion is a common solution to this problem.However,the traditional software radio platform uses multiple discrete devices to achieve its functions,which is large in size,high in energy consumption and poor in portability.AD9361 is a high-performance RF transceiver chip.A single device integrates all the necessary modules of RF front-end and baseband to RF signal conversion,and has the advantages of large bandwidth and low power consumption,which can provide a good choice for the design of software radio platform.On the other hand,QPSK modulation and demodulation method has the advantages of high frequency band utilization,strong anti-interference and simple circuit implementation,which has been widely used in the field of medium and high-speed communication.Based on the above considerations,this article designs a set of QPSK wireless transceiver system based on AD9361.The article first introduces the theoretical structure of the wireless transceiver system,and then analyzes the design schemes of the baseband part and the RF part of the system in detail.The baseband section first explains the basic principles of DQPSK modulation and the design methods of modules such as differential encoding and shaping filters.Then it introduces the design of the demodulation section.The polar Costas loop is selected as the carrier synchronization loop,and the FFT frequency is also designed.The bias estimation module estimates and compensates for the large carrier frequency offset.The bit synchronization loop selects the Gardner loop algorithm,which can effectively calculate the bit timing error.The frame synchronization selects the Chu sequence scheme.Later,the designed modulation and demodulation system was simulated and verified with Matlab,and the previously designed baseband scheme was designed and implemented on Vivado.After that,the RF scheme based on AD9361 was designed.First,the working principle of AD9361 was explained,and then the configuration design of AD9361 was introduced.The configuration method was mainly completed by FPGA writing corresponding values to each register of AD9361 through SPI bus.The configuration process of module registers such as transmitter and receiver,frequency synthesizer,and parallel data interface is introduced in detail.Finally,a hardware test was performed on the wireless transceiver system,which verified that the designed system has good transmission performance,laying an important foundation for the subsequent research and development of the transceiver system.