Research And Application On Radio Direction Finding Technology Based On Airborne Platform

Radio direction finding technology is a discipline that not only closely relates on national defense but also on production and life.This technology used in electronic reconnaissance and radio spectrum monitoring in the areas of military field and civilian field respectively.In this thesis,the radio direction finding technology is mainly used in the field of interference source finding,with the purpose of obtaining the location information of radio transmission source.For the airborne platform,it is necessary to obtain azimuth and pitch angles at the same time.At this stage of interference source finding for practical application,commonly used method is to use directional antenna in the way of artificial searching or vehicle-mounted equipment.Further,some hot spots may use multiple monitoring station to form a grid area.However,this approach will lead to disadvantages both on investment and flexibility.Therefore,this thesis presents a single-station radio direction finding scheme for airborne platform,which has the advantages of real-time direction finding and flexible maneuver.As a supplement to grid monitoring,it is possible to achieve a rapid interference source finding for some non-personnel-intensive areas but with strict control of the electromagnetic environment,such as suburbs around the airport and area along the railway.As an integral part of the ground-air integration monitoring platform,a future research direction is explored in this field,which has strong reference significance and practical value.For this purpose,this thesis has done the following work:First,the scheme of direction finding for the traditional platform was redesigned and optimized to meet the application of airborne platform.Specifically embodied in the following two aspects,one is the use of small and lightweight five-element antenna and dual-channel broadband receiver,so that the whole system structure is more compact;the other is the use of improved interferometer scheme to ensure a higher efficiency in the real-time measurement.Secondly,a detailed analysis of the high-precision phase difference measurement is carried out to ensure the accuracy of the whole interferometer system.This thesis proposes a cross-spectrum method based on Sparse Fourier Transform(SFT),which improves the measurement efficiency of phase difference and is suitable for airborne platform with high real-time requirement.This is the innovation of this thesis.After that,the phase difference between the real-time measurement and the sample library are matched according to the principle of the cross-correlation based on the idea of matching filtering to determine the direction of the incoming wave.Finally,real field testing of the completed DF system is performed.In order to reduce the test cost,and as far as possible to simulate the air environment,the two test fields is chosen to have a certain height difference in the open places.The test results show that the system can meet the requirements of engineering application.