Design Of Digital Beamforming Circuit Based On Software Defined Radio

Because of the variety of natural disasters and the uncertain location of emergencies,the emergency communication system needs to meet the requirements of signal coverage and large bandwidth in a variety of complex environments,but also needs to be small and easy to deploy.The concept of software defined radio technology is to use general hardware circuit to design the communication system,and use flexible software processing to realize the compatibility of multiple standard signals at the baseband,so as to reduce the overall size of the communication system and make the system have the advantages of high flexibility and portability.In this thesis,the architecture of Software Defined Radio is used to design the MIMO digital beamforming circuit.This approach will give full play to the great potential of digital beamforming in signal coverage and improving bandwidth.At the same time,it can greatly reduce the overall size of the communication system with the help of the flexible advantages of software,which makes this circuit very suitable for solving the problem of insufficient signal coverage in emergency disaster rescue site.The main work of this thesis is as follows:Firstly,this thesis analyzes the relevant principles of Software Defined Radio and digital beamforming technology,and designs a MIMO digital beamforming circuit with four transmitting and four receiving channels based on the Software Defined Radio architecture.The circuit is mainly composed of RF transceiver,transmitting front-end circuit,receiving front-end circuit,FPGA and so on.The RF transmission performance of the transceiver front-end circuit is optimized in the 2.4GHz frequency band.Secondly,the control principle of amplitude and phase of baseband signal is analyzed,and the amplitude and phase controller of baseband is designed.The amplitude and phase controller uses AXI＿Lite bus to configure amplitude and phase control parameters.Finally,the software of digital beamforming circuit is designed,and the key amplitude and phase adjustment function in digital beamforming at the transmitter of the circuit is tested.The power regulation and phase regulation functions of digital beamforming subarray circuit are tested in 450 MHz,900MHz and 2400 mhz frequency bands respectively.It is found that in the above three frequency bands,when the signal amplitude of each channel on the baseband side is attenuated in the range of 0 to 1 in steps of 0.125,the output signal power of the RF terminal also shows a downward trend.At the same time,when the signal phase of each channel is stepped at 11.25 ° on the baseband side and the relative phase offset is carried out within 0 to 180 °,the output signal phase of the RF terminal also has an obvious increasing trend.The test results show that the digital beamforming circuit designed in this paper has the main function of digital beamforming at the transmitter..