Systematic Design Of Radar Astronomy Science Receiver

As an important target of radar astronomy,asteroids,space debris and various other man-made or natural objects in near-Earth space are of great significance to the high-precision detection and tracking of them.The digital receiver is the key module in radar astronomy detection.It can receive,process,forward and record the echo signal in real time,which is of great significance to radar astronomical detection.In this paper,according to the requirements of the application environment and the research situation of the receiver at home and abroad,the system realizes real-time data processing and signal recording for the two input signals generated by the orthogonal polarization antenna.The system is based on the software radio architecture,and three layers of ADC,FPGA and ARM hardware board are selected as the hardware realization foundation of high-speed analog-to-digital conversion and digital signal processing.The general high performance hardware equipment and the way of software customization guarantee the digital frontend,software function and easy upgrading of the system.This paper completes the design of the whole FPGA hardware logic circuit and the design of RASR software platform.The hardware logic circuit includes four parts: input/output interface module,digital down conversion module,pulse detection module and data transmission module.FPGA design uses its parallel processing characteristics to achieve high-speed digital down conversion,polyphase filtering,data transmission and other functions.In view of the characteristics of low duty cycle of received signals,the level trigger mode can be selected to complete the data transmission and recording and reduce the load of the system.The software platform is based on C/S architecture,and the software design of client layer and application layer is completed.The upper computer software is based on the Pyqt5 interface design platform.Under the multi-thread working mode,the user interface design is completed with Python language,which can realize the system initialization,self-check,digital signal processing parameter configuration and memory control and other actions,and can be run across platforms.At the same time,Windows system is based on Win Pcap and Linux is based on Hashpipe to complete the design of data storage software.Under the data transmission rate of up to 750Mb/s,the system can realize stable and effective data packet recording.Finally,this paper completes the test of the RASR system and verifies the function of the system.It can realize down conversion processing and stable data recording of any IF signal in the frequency range of 0-560 MHz.The frequency conversion step is 1k Hz.The output signal bandwidth is 20 MHz.The bit width is8.The time word step is 1 microsecond,and the accuracy reaches 1 nanosecond level.The overall design meets the target requirements of the radar astronomy digital receiver.