Analysis And Optimization Of TDOA Location And Limit Performance Of Short Wave Emitter

Shortwave communication is a communication mode in which electromagnetic waves complete information transmission through the reflection and refraction of the atmospheric ionosphere.It does not need relay stations and network hubs.It has a better anti-interference and anti destruction,and has the advantages of over the horizon transmission.It has irreplaceable advantages in military information acquisition,enemy target reconnaissance and long-range route flight.Due to the complex influence of ionosphere on electromagnetic wave propagation,the passive positioning of short wave radiation source has become an urgent problem in the field of electronic reconnaissance.Based on the assumption of uniform stratification of ionospheric electron density,focusing on the location method of time difference of arrival,this paper studies the location method and error limit performance under the complex ionospheric model closer to the actual situation,and studies the method to improve the location performance from the perspective of station layout.The main work and contributions of this paper can be concluded as follows: 1)in the singlelayer ionospheric model,for the positioning problem of double jump propagation mode,the analytical expressions of ground distance and group path are derived,so that the positioning problem is described as a constrained optimization problem,and the calculation formula of Cramer Rao bound of this positioning method is derived combined with geometric characteristics,The limit performance of short wave positioning method in double hop propagation mode is given;2)Due to the large difference between the single-layer ionosphere model and the actual ionosphere,which can not truly reflect the performance of the positioning algorithm,the Bradley / dudeney three-layer ionosphere model is introduced,the mathematical model of location based on TDOA is given,the location information of radiation source is obtained,and the calculation formula of Cramer Rao bound of the positioning method under this complex model is deduced,Make the theoretical limit performance of emitter target positioning closer to the real value;3)In order to improve the positioning performance,the optimal station layout problem is modeled under the criterion of minimizing geometric accuracy factor,which is described as a complex nonlinear optimization problem.Based on the golden sine guidance mechanism(GSGM),a golden sine particle swarm optimization algorithm is proposed,which is guided by the golden sine guidance mechanism,The secondary update of the speed and position of individual particles overcomes the shortcomings of the existing particle swarm optimization algorithm,which is easy to fall into local optimization and slow convergence,so as to improve the accuracy and timeliness of optimal station layout.