Research And Implementation Of Direction Finding System Based On Spatial Spectrum Estimation

With the rapid development of wireless communication technology,the number of radio transmitting equipment and terminals is growing rapidly,meanwhile,Radio interference is becoming more and more serious.Radio spectrum as a non renewable strategic resource,it is closely related to social stability and economic development.In China,the radio management agencies mainly use the radio direction finding system to control the use of spectrum.At present,the radio direction finding systems built are still based on the correlation interferometer direction finding system,these systems can not meet the requirements,and lack of ability to distinguish multiple signals.In this thesis,two main subspace algorithms are researched.For UCA(Uniform Circular Array),a method of transforming uniform circular array into virtual linear array by mode space transformation is introduced.Combined with engineering application requirements,a 9-channel RF receiver is designed,corresponding with antenna array elements.The simulation results show that the 9-element uniform circular array designed in this thesis can distinguish multiple signals easily.In order to distinguish coherent signals,an improved spatial smoothing algorithm is researched.The effectiveness of the algorithm is verified by simulation.In order to solve the problem of large computation of multi signal classification algorithm,a high performance TMS320C6678 8-core DSP chip is used in the system.Through the multi-core collaboration to optimize the spectral peak search,improve the algorithm implementation speed.At last,the actual test is completed in the standard open area test site.The direction finding accuracy,direction finding resolution and income wave number technical indexes of the system are verified.The direction finding system designed and implemented in this thesis based on spatial spectrum estimation algorithm.Compared with the older direction finding systems of radio management department,it has multi signal distinguish ability and higher direction finding accuracy.It will greatly enhance the ability of radio regulatory agencies to investigate and deal with interference.