| In recent years,information and electronic technologies have continuously developed,and the processing capabilities of signal processors have been continuously strengthened.The pre-research and application of software radio technology in radar are becoming more and more popular,which has spawned a series of new applications and software radars with new systems.Among them,the spaceborne radar based on software radio design has attracted much attention.Foreign countries have embarked on spaceborne detection research many years ago,and it has been very effective.However,it started late in China,and the research is almost blank.This paper takes the very low frequency band and low frequency band as the research background,and relies on the national major instrument special projects related to spaceborne radar to design a multi-functional and multi-application radar signal source.The design of signal sources and related experiments will provide key knowledge reserves for major national instrument special projects from experimental design to system simulation to functional realization.At the same time,applying this signal source to spaceborne radar or other various radars can greatly expand the application of radar equipment.The specific research work of this article is as follows:The signal source is designed under the GNU Radio open source software platform using software radio technology and frequency division multiplexing technology.It has the functions of flexible and adjustable transmission signal frequency,multi-frequency transmission and frequency sweep stepping.In addition,a radar signal transceiving system was built based on the signal source.Through closed-loop experiments,the radar signal transceiving system based on the signal source was verified and evaluated to be stable and reliable.First of all,this paper summarizes the current status and development direction of software radio technology and signal generators.The advantages of flexible software,open source and high development and production efficiency are described.The development history of the signal generator is briefly described.The necessity of studying the frequency division multiplexing radar signal source is analyzed,and the research background and main function introduction of the signal source are analyzed.Then,the signal source system plan is designed in this paper.The hardware equipment is mainly software radio peripheral N 210,and the radio frequency daughter board is LFTX/RX.The software mainly uses GNU Radio.The entire system process runs under Ubuntu.Next,the signal source performance was tested and analyzed.It mainly includes phase matching,one frequency signal frequency hopping,multiplexing four frequency point frequency hopping test.The algorithm of the short-time Fourier transform is improved,and the tenth-order frequency hopping data is processed to obtain the experimental results that meet the expectations.Finally,the evaluation and verification of the field test of the signal source are carried out.The closed-loop test is carried out and the experimental data is processed by designing the radar signal receiving and sending system.A preliminary conclusion is drawn that the signal source can be used in field tests to improve the performance ofradar signal transceiving systems. |
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