Abstract: The acquisition of projection matrix is the key step in computerized ionospheric tomography based on pixel. Because of the algebraic method, the traditional method not only has a complex process, but also cannot get unique solution. The unique solution cannot be obtained by using traditional method, and it is necessary to determine which solution satisfies the condition. Aimed at this deficiency, a method of obtaining projection matrix based on vector relation is proposed by analyzing the intersection point between satellite signal ray and 3D pixel plane. The novel method reduces the number of unknowns and the complexity of the computation, and obtains the unique solution without determining. It reduces the redundancy and improves the efficiency.

Key words: ionosphere, computerized ionospheric tomography, projection matrix, vector