Research On Fast And High-Precision Time Difference Measurement Technology

The precise direction finding technology is mainly used to measure the direction and position information of the target radiation source,and plays a vital role in a series of tactical technical actions such as signal detection,sorting and identification,interference guidance and anti-radiation attack.As the core technology of direction finding,the research of time difference measurement technology is of great significance to improve the accuracy and efficiency of direction finding.Therefore,this thesis has carried out in-depth research on fast and high precision time difference measurement technology.Firstly,the basic method of time domain time difference measurement is researched,and then frequency domain time difference measurement technology is proposed,which effectively improves the accuracy of time difference measurement.On this basis,a time-frequency domain joint time difference measurement technique is proposed.Finally,the influence of complex environment on the measurement precision of time difference measurement technology is studied,and the corresponding solution is given.The specific research content is:(1)The time domain time difference measurement technique of the signal is researched.The basic methods of time domain time difference measurement are studied,the measurement error and application range of different measurement methods are analyzed.Then,the influence of factors such as signal-to-noise ratio(SNR),envelope amplitude and steepness of the leading edge on the measurement accuracy of time domain time difference is discussed.Finally,the accuracy of time domain difference measurement of four typical radar signals under different SNR is analyzed by simulation,and the effectiveness of time domain time difference measurement technology is illustrated.(2)The frequency domain time difference measurement technique of the signal is researched.Aiming at the problem of theoretical error of time domain time difference measurement technology,a frequency domain time difference measurement technique is proposed.Firstly,The frequency domain time difference measurement simulation and analysis are carried out for the four radar signals with different main spectrum features,and compare the algorithm complexity of time domain and frequency domain time difference measurement technology.The results show that the frequency domain time difference measurement technology makes up for the shortcoming of the theoretical error of the time domain time difference measurement technology.The high precision time difference estimation value can be quickly obtained under a certain SNR.At the same time,the influence of SNR on the measurement accuracy of frequency domain time difference of different signals is researched.Combined with the characteristics of time domain and frequency domain time difference measurement,a time-frequency domain joint time difference measurement technique is proposed.Experiments show that this method can obtain high-precision time difference measurement values.(3)The influence of complex environment on time difference measurement technology is researched.Two aliasing methods for simultaneous multiple signals are studied,and two corresponding time difference measurement methods are given.Then,based on the influence of simple multipath propagation conditions on the measurement performance of the main path signal,the following two multipath signal processing methods are given: time difference measurement technology based on signal leading edge and time difference measurement technology based on spatial filtering.The simulation results show that under certain multipath conditions both methods can effectively improve the accuracy of the time difference measurement.