Design Of Receivers For Radar Astronomy

Radar astronomy is an important factual basis in astronomy.The observation of celestial bodies is an important research content of radar astronomy.There are many potential safety hazards in near earth space,such as near Earth Asteroids,man-made satellites and all kinds of celestial bodies.Their observation can provide important scientific data for Astrophysics,Galaxy research and other fields.At present,in many application scenarios,different observation requirements are put forward for the of digital receivers.Some scenarios attach great importance to the accuracy of data and the timeliness of signal reception and processing.Some scenarios hope to sample multi band data.Some scenario devices are fixed in the machine room,while some scenario devices are laid in the outfield,which are more favored for portability and cost,which leads to different types of digital receiving devices.Aiming at different application scenarios of radar astronomy,this paper studies the relevant technologies of corresponding digital receiver equipment,and completes a portable RSDR(radar software defined radio receiver)equipment with wide-band monitoring and six channel input based on the cascade design architecture and the requirements of portability and multi-band observation.The hardware consists of SDR core board,data interface adapter board and zynq core board.The SDR core board samples the six channel data.The input signal realizes low-noise amplification,filtering and mixing in the RF module,and is converted to baseband before analog-to-digital conversion.The generated digital signal is transmitted to the subsequent FPGA through the high-speed interface for processing.It is encapsulated in the FPGA,and the data is packaged and transmitted to the upper computer through the Gigabit network,Realize the transmission of signal data.The upper computer realizes the processing and imaging of data and the communication programming function of FPGA and SDR board through MATLAB.Then,according to the requirements of long-time continuous data storage and processing under the condition of weak received signal,the second RASR(Radio Science receiver)-K7 receiver is designed.The system is composed of ADC,FPGA board and arm.The front end samples the signal with 1.12 Gsps sampling rate,Then the data is processed by digital down conversion and multi-phase filtering,and then packaged for Gigabit network transmission.The upper computer realizes the effective recording of data through Win Pcap,and realizes the control and programming of the underlying arm and FPGA through Python.In this paper,the design and testing of the two systems are completed.The data acquisition test and host computer function test of the two systems are carried out respectively.The RSDR system can realize the signal reception and snapshot storage of 20 MHz bandwidth near any frequency point in the70mhz-6ghz carrier frequency,and the bit width is 12 bit.The RSAR-K7 system can realize long-time reception of broadband signals in the wide-band range of 0-560 mhz,and can select any 20 MHz bandwidth signal for long-time continuous data transmission and storage through configuration.The output bit width is 8 ～ 16 bit.The experimental results fully show the accuracy of the working data of the two systems and meet the needs of radar astronomical observation.