Study On The High-definition Time Measurement For The Time-Difference Location System

In the modern war,the hidden detection and a high-definition positioning accuracy makes the time-difference locating system become a main way to realizing the passive locating.But its locating accuracy is impacted by various factors and constrains,of which the measurement accuracy of the pulse TOA(time of arrival) is the key factor.With the continuous improvement of the modern electronic reconnaissance and the detection ability to the target signal,the tracking distance to the target signal becomes farther and farther.At the same time,the far target signal detection is effected by many unfavorable factors,such as multi-path transition and the interfering from the electromagnetism signal.As a result,the difficulty of the detection is much bigger than that of the near signal while maintaining the same accuracy,and that requires more effective methods to measure the TOA of the pulse signal.In this paper,the system composition,the operating principle and the project implement of the TDOA(time difference of arrival) measurement is introduced,which is on the basis of the designing of the TDOA passive locating system.The TTWT(the two way of transferring) technique to realizing the TDOA measurement is selected after analyzing and comparing extensive methods of measuring the time.One of the key technologies--the technique of measuring the TOA of the pulse signal and relative implement methods are mainly studied in the article.Based on the existing time measurement techniques,this paper presents a method which is digital multi-channel phase-shift combined with the pulse-edge normalization forming technology to form the high-definition time measurement system.The precision could achieve ns level when measuring the TOA of the pulse signal.With the help of the FPGA chip,a high-definition measurement system base on the multi-phase clock and the pulse-edge normalization forming technology is designed.Finally,the feasibility of the technique is tested by the experiment.The result indicates that the technique could efficiently improve the measuring precision of the TOA of the pulse signal,without adding the frequency of the clock and the system's complexity,which provides an important technical means to the further improvement of the electronic detection system..