Joint inversion method based on inclined return ionogram and computed tomography

Abstract

The invention provides a joint inversion method based on inclined return ionogram and computed tomography. The joint inversion method is characterized in that various pixel point electron density initial values of a tomographic model can be corrected by adopting inclined return inversion, and prior information can be additionally provided firstly, and then the tomographic inversion can be carried out based on a pixel base model, and then ionosphere TEC values of various rays can be solved by adopting GPS observation data; a coefficient matrix can be determined according to satellite signal rays; and then the reverse engineering of the electron intensity can be carried out. Compared to the conventional ionosphere tomographic method, the method provided by the invention is advantageous in that the precision is improved to a certain degree, and the accordance with the vertical observation data is better; when the observation data is insufficient, the defect of the conventional ionosphere tomographic method of the overdependence on the empirical model can be overcome by adopting the joint inversion method; and according to the invention, the joint inversion method is the first method combining the inclined return detection data with the GPS data, and therefore the insufficient GPS data problem can be effectively improved.

Description

technical field [0001] The invention relates to a joint inversion method based on oblique return ionogram and tomographic imaging, which belongs to the field of intelligent control. Background technique [0002] The ionosphere is the medium for radio wave propagation. When the ionosphere detection system is working, the ionosphere is the transmission medium for radio signals. The distribution and fluctuation of the electron concentration in the ionosphere will cause changes in the ionosphere’s refractive index, thereby affecting the echo signal. Influence, resulting in phase disturbance of the echo signal, broadening of the Doppler spectrum of the echo signal, and reduction of the signal-to-noise ratio. Therefore, in a broad sense, mastering the distribution state and changing law of ionospheric electron concentration is conducive to improving the accuracy of radio communication, timing, positioning, navigation, telemetry and early warning systems. [0003] In the actual io...

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Problems solved by technology

[0004] In traditional ionospheric tomography experiments based on GPS data, due to the small number of ground receivers in the area to be reconstructed and usually uneven distribution, coupled with the limited elevation angle of GPS rays, vertical rays and near-vertical Rays account for the vast majority, and only the rays that fall within the upper and lower boundaries of the area to be inverted can be used for tomographic inversion. Therefore, it is difficult to obtain comprehensive information on the internal structure of the ionosphere in the area to be inverted. Therefore, the tomographic inversion After the ionospheric space is discretized, some pixels do not have GPS rays passing through, that is, there is no observation information to correct, then the electron density value of the pixel is consistent with the initial value, without any improvement, which means that the ionization based solely on GPS data There is a general error between the electron density inversion results of layer tomography and the true distribution of ionospheric electron density

[0005] On the other hand, the iterative initial value in ionospheric tomography is often given by the international reference ionospheric model, but because the IRI model is a statistical empirical model, it can only reflect the In the average state, especially when the space weather is abnormal or there is a disturbance, there is a relatively large difference between the electron density value provided by the IRI model and the true value of the ionosphere

Because of these problems, the reconstructed ionospheric electron density distribution Figure 1 Generally, there will be a certain degree of distortion, and the intuitive performance on the image is that the electron density value between adjacent pixels is discontinuous, and there are often some mutations.

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