Research On Key Technologies Of Wideband Radar Digital Receiver And Signal Processing Based On TIADC

Space target threat assessment,space debris collision warning,near-earth space detection and other applications require fine measurement of space targets.Radar is one of the most effective techniques for space target surveillance and recognition,which can acquire rich information of space targets at any time and in any weather.The resolution of ISAR(Inverse Synthetic Aperture Radar)image can be improved by increasing the bandwidth of radar and combining appropriate ISAR imaging technology.The wideband radar digital receiver can directly acquire IF signals and even RF signals,and has the advantages of high signal-to-noise ratio,stable amplitude-frequency characteristics,and flexible algorithm implementation.With the increase of ISAR transmitting signal bandwidth,the sampling rate and bandwidth of radar digital receiver need to match the transmitting signal.Research on wideband radar digital receivers will provide important technical support for improving the cognitive,recognition and surveillance capabilities of space targets for our country.This paper firstly explains the research background and realization significance of the subject.Then the development status of wideband radar digital receiver,the research status of parallel sampling technology,the research status of TIADC(Time-Interleaved Analog-to-Digital Converter)channel mismatch calibration and the development status of TIADC system are investigated.The research direction of the thesis is clarified.Research on wideband radar signal receiving technology based on directly IF sampling is carried out.For some applications,single-chip ADC is difficult to meet the requirement of receivers.TIADC technology based on multi-channel ADC chips is introduced into wideband radar digital receivers.The channel mismatch model of broadband TIADC system is established,and the effects of channel mismatch on the spectrum and dynamic performance of the sampled signal are analyzed.And the synchronous acquisition method of multiple ADC chips based on JESD204 B subclass 1is pointed out.Aiming at the problem that the TIADC channel mismatch seriously deteriorates the dynamic performance of the system and the shortcomings of common calibration methods,according to the practical application requirements,the automatic estimation algorithm of wideband TIADC channel mismatch based on sinusoidal fitting and the mismatch compensation algorithm of wideband TIADC channel based on perfect reconstruction are proposed.The estimation algorithm can accurately measure the wideband TIADC channel mismatch between ADC chips,and only need to deal with the concerned frequency band.The compensation algorithm realizes the high precision compensation of TIADC channel mismatch in wideband frequency.Research on signal processing technology of wideband radar is carried out.The digital down conversion technology,pulse compression technology and bandwidth expansion technology of wideband radar digital receiver are studied.The pulse compression model of the LFM(Linear Frequency Modulated)signal in directly IF sampling is established.The influence of the TIADC channel mismatch on the LFM signal pulse compression is analyzed.Aiming at the problem of bandwidth accumulation reduction of TIADC system consisting of multiple ADC chips,a bandwidth extension method based on wideband gain estimation is proposed.This method effectively expands the bandwidth of TIADC system consisting of multiple ADC chips.A wideband radar digital receiver based on TIADC technology is designed.Firstly,the design target is defined.This paper focuses on the overall design,hardware design and software design of wideband radar digital receiver.The test results show that the sampling rate of wideband radar digital receiver is 10.4 Gs/s and the quantization bit is12.In the frequency range of 0.1 GHz to 4.7 GHz,the ENOB(Effective Number of Bits)is more than 7.5 bits,the SFDR(Spurious Free Dynamic Range)is more than 57 dB,and the stable transmission rate is 40 Gb/s.It has the ability to directly sample and record radar IF echoes with the bandwidth over 3 GHz.This paper combines theoretical research with engineering practice,and solves many technical problems encountered in the process of the digital receiver design and development.The developed receiver has been successfully applied and achieved good results.This paper lays a theoretical and technical foundation for the engineering application of wideband radar digital receiver based on TIADC.