High Precision TEC Inversion Based On Tri-band Beacon

Ionosphere will affect the propagation of radio waves,and more and more data show that earthquakes with larger magnitude are often accompanied by electromagnetic anomalies.Therefore,whether it is for the need of accurate navigation or to reveal the mechanism of electromagnetic effect of earthquake to achieve the purpose of earthquake prediction,we need to obtain high-precision ionospheric information.The technology of Tri-band beacon is a new type of total electron content measurement technology,which uses the tri-band beacon transmitter on the low orbit satellite to transmit a group of coherent signals composed of three frequency signals to the ground,and then the Doppler frequency shift of the signals received by the ground receiver to measure TEC and obtain large-scale and high-precision TEC and electronic density profiles through ionospheric CIT Technology.The three kinds of Doppler shift of three frequency signals are differentiated,and three components of differential Doppler shift can be obtained.The relationship between the difference Doppler shift and the electron concentration can be obtained by mathematical relationship.Compared with the traditional Ionospheric TEC inversion method,the technology of triple frequency beacon has the characteristics of high measurement accuracy and good determination of phase integral constant.In order to explore the theoretical process of high-precision Ionospheric TEC inversion by three frequency beacons and analyze the influence of different observation errors on the inversion accuracy,a method of simulating Doppler frequency shift of satellite signal is proposed to study the inversion of Tec by using the technology of Triband beacon.Through known satellite orbit coordinates,receiver coordinates,satellite altitude angle and ionospheric background information,Doppler frequency shift information in the process of signal transmission is simulated by using the law of signal propagation,and the relative TEC is calculated.Then,the phase integral constant is estimated by multi station method,and the absolute TEC of dual frequency is calculated,and then the fractional part of Doppler phase shift is used to combine with the three frequency phases integral constant The high precision three frequency Tec is calculated.The conclusions are as follows:1)The inversion of high-precision Ionospheric TEC by three frequency beacon is feasible and effective theoretically.In the case of only considering observation error,the inversion error of double frequency technology is about 2 TECU.The accuracy of Tec inversion can be improved by using the triple frequency beacon technology.Without considering the error,the TEC and background Tec errors are 10-7 TECU,which also shows the correctness of simulation algorithm.2)The observation error has a great influence on the inversion accuracy of the three frequency beacons.The inversion accuracy is 0.1-0.2 TECU under the condition of 1 ° observation error,and the inversion error is about 0.2 to 0.4 TECU under the condition of 3 ° observation error,and the inversion error will reach about 0.8 0.5-0.8TECU under the condition of 6 ° observation error.3)Compared with the results of the tri-band beacon technique,the observation error has no significant influence on the inversion of dual frequency tec.At present,due to different reasons,only double frequency data are provided on the satellite.Based on the simulation data of three frequency beacons,this paper theoretically proves the possibility of Tec inversion of the elevation accuracy of the three frequency signals.It is believed that the technology of triple frequency beacon can bring more development for the future ionosphere research.