| Aircraft formation combat is playing a more and more important role in modern war and has become a new main air combat mode.Therefore,it has become a hot issue to study how to realize the real-time and high-precision mutual positioning of formation members in the environment of navigation satellite denial.Aircraft formation mutual positioning usually includes ranging and angle measurement.At present,the research of spread spectrum signal ranging technology has been relatively mature,but there is little research on aircraft formation angle measurement technology.The correlation interferometer has the advantages of high precision,good real-time performance and simple implementation,and can well meet the requirements of high-precision angle measurement of aircraft formation.Based on the background of aircraft formation,this paper studies the angle measurement technology of correlation interferometer.The main contents are as follows:Based on the analysis of the characteristics and requirements of aircraft formation angle measurement,a method of formation angle measurement using correlation interferometer is proposed.Since the aircraft formation uses K-band signal for angle measurement,the antenna array radius must be much greater than 1 / 2 of the signal wavelength,and whether the phase ambiguity will occur when the antenna radius of the uniform circular array correlation interferometer is much greater than half wavelength,there is no special research and exact conclusion at present,A mathematical derivation method is proposed to calculate and demonstrate the condition that M-element uniform circular array correlation interferometer has no phase ambiguity.Taking 5-element array as an example,the maximum radius wavelength ratio without phase ambiguity is calculated.The effects of noise,antenna radius and standard array on the angle measurement accuracy of correlation interferometer are analyzed and verified by simulation.The simulation results show that the 5-element uniform circular array correlation interferometer designed in this subject has good performance and can meet the requirements of aircraft formation angle measurement index when the signal-to-noise ratio is greater than-5d B: the angle measurement error is no more than0.5 ° in the range of pitch angle [-45 °,45 °](1 δ),Not more than 1 ° within the range of pitch angle [-65 °,65 °](1 δ)。The angle measurement using spread spectrum signal correlation interferometer can well meet the needs of aircraft formation to achieve high-precision and low interception angle measurement in complex electromagnetic environment.Aiming at the problem that the current spread spectrum signal angle measurement methods generally lose spread spectrum gain,resulting in the inability to achieve high-precision angle measurement under the condition of low signal-to-noise ratio,a method based on correlation despreading peak detection is proposed to extract the phase difference of spread spectrum signal The angle measurement method of spread spectrum signal correlation interferometer makes full use of the spread spectrum signal gain and has better performance compared with several main spread spectrum signal angle measurement methods.The simulation results show that this method can still meet the angle measurement accuracy requirements of aircraft formation under the condition of signal-to-noise ratio of-16 d B.Aiming at the problems of unscientific test method,complex test process and low accuracy of correlation interferometer,a microwave anechoic chamber test scheme of correlation interferometer is designed,which ensures the accuracy,efficiency,simplicity and feasibility of system test through high-standard test environment,high-performance test equipment,scientific test method and high-precision automatic control equipment The scheme can be applied to the test of high-precision radio direction finding system. |
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