The Realization Of Doppler Direction Finding System On Key Technologies

With the development of science and technology and the increasing demand for marketization,radio monitoring and management has been included in the development of the country.Radio direction finding systems are mostly used for navigation purposes in the early time.Most modern radio direction finding systems are used to extract the radio signal parameters.Doppler direction finding systems are an important means of radio monitoring,for a long time,it occupies the most part of the market of direction finding machines.With the development of digital,highly integrated chips in the recent years.Doppler direction finding technology at home and abroad is running into a rapid development road,the major domestic and foreign manufacturers continue to the traditional Doppler program to improve the design of many new radio direction finding techeniques and algorithms on Doppler direction finder,making the Doppler direction finding machine higher precision,less polarrization error,the equipment is more compact,lower cost and higher market penetration.In this paper,three kinds of radio direction finding systems are studied.On the basis of comparative analysis of various DF schemes,The single-channel quasi-Doppler direction finding system with high precision and low cost is selected.In the view of the shortcomings of the traditional Doppler direction finding scheme and the problem of non-circularity of the direction finding,to improve the program,the data preprocessing method,the group vector method and the rotation vector method are added to make up for the deficiency of the traditional scheme,and the problem of the non-circularity is solved.When the traditional scheme is improved,the influence of many parameters is considered,such as the selection of sampling points,the choice of antenna rotation speed,the choice of antenna aperture,the choice of input signal to noise ratio,the selection of sampling frequency,etc.,These parameters are optimized in terms of direction finding accuracy,algorithm complexity and device stability,so that the Doppler direction finder is theoretically feasible under optimal conditions.In this paper,the improved scheme is implemented.In order to facilitate the theoretical analysis of the improved scheme,this paper first implements Labview software.In order to facilitate the practical application,this paper finally uses the FPGA as the hardware platform,and verilog language is used to realize the hardware.Before the hardware implementation,this paper designs the appropriate three-stage band-pass filter and phase-locked loop through theoretical analysis and simulation.The structure and parameters of each key module are realized.After solving many practical problems,the Doppler direction finding machine is tested and the performance index of the scheme is obtained.Compared with the traditional direction finding machine,it is found that the device has a certain improvement in the direction accuracy and the machine is highly mobility that can be used as airborne,car equipment and ship equipment.