Design And Implementation Of PD Radar RF Prototype Based On Software Defined Radio

With the arrival of intelligent wireless communication era,the electromagnetic environment of radar is increasingly complex,flexibility of requirements are getting higher and higher,Customized design of traditional standard radar is facing many challenges.Software Defined Radio(SDR)was proposed since the nineties of last century,with its excellent openness and flexibility in the field of mobile communications,wireless measurement and other fields,SDR has played an important role.In recent years,the design of SDR has gradually penetrated into the radar field.The active US military supersonic stealth fighter F-22 was equipped with radar system which is based on software radio new radar.Benefit from the integration between the setting radar and the telecommunication,flexible performance parameters can be altered within a sensible battlefield phenomenon,thus,the F-22 can survive with a better combat effectiveness.Therefore,the radar based on software radio is a new research hotspot of radar design.The RF front end,which is the heart of the system regarding sending and receiving messages,supposes to be one of the key issues in the design.This paper is based on a key radar signal processing project supported by the national ministries.The design and implementation of the new radar radio frequency prototype are studied,especially for the radar RF front end.The overall design goals of the system are listed as follow: The designed RF front end was aiming to own an adjustable range of RF carrier frequency,which cover from the low up to the medium radar frequency band;It consists of a precise frequency selection and a good dynamic range;the sending and receiving parameters are adjustable and the link-combination of the RF prototype are reconfigurable.The RF prototype uses the zero-IF architecture,and RF transceiver channel was designed based on the idea of the building blocks.The algorithm of the filter link building blocks and the gain network blocks were realized by Matlab and Labview link simulation models.The relationship between the output response of the simulation model and the parameters of each building block can be carefully investigated.According to the specific frequency and gain index of the design,the building block of the SDR RF transceiver channel is determined.In addition,due to the requirements of the software radio system hardware and the software coordinatio,we addressed on the OSI hierarchical design whereas commonly used in the computer network system.Concerning the characteristics of the design,the system can be divided into four bottom layers which including the physical layer,the interface layer,the driver layer and the application layer.Generally,the realization blocks of RF link building can be regarded as the physical layer.The RF front-end,the partial RF control interface and embedded processor,and the FPGA communication interface are normally settled into the interface layer.The driver layer,a kind of transition between the software and the hardware,not only extracts the hardware register as a parameter of the software configuration function,but also delivers the API functioned feedback to the hardware register in the form of a driver file.Moreover,the application layer can open up versatile applications: the efficient connection between the system and the users,and realization of the API function from the basic RF features.Among them,the realization blocks of RF link building belong to the physical layer;RF front-end and RF control part of the interface,with the RF control part of the embedded processor and FPGA communication interface belong to the interface layer;The driver layer belongs to a transition between software and hardware,On the one hand it abstracts the hardware register as a parameter of the software configuration function.On the other hand,the return function of the API function of the software is written to the hardware register in the form of a driver file;Application layer is mainly used for system and user interaction and the basic RF function of the API function to achieve.Finally,the radar RF prototype designed in this paper was mapped to the board-level circuit.The design of the control part was implemented by Xilinx's Zedboard,the RF front-end was implemented by mapping to ADI's AD9361.The PD radar RF prototype,designed based on the software radio,was determined to reach an adjustable main frequency varying from 70MHz~ 6GHz which could cover the HF band to the C band of the radar spectrum.The dynamic range of the automatic gain was 66 d B which was higher than the industry standard level(60 d B),hereafter,a wider range of the gain balance adjustment can be definitely demonstrated.By using software configuration and hardware implementation method,our system was intimated to accomplish the RF prototype signal transceiver through configuring the specific RF parameters.