The Effects And Researches Of Ionosphere To Gps Positioning

GPS is the abbreviation of Global Positioning System, is the second generation navigation satellite system of the United States Department of Defense, is a24-hour radio positioning and timing system for the global that based on man-made satellites, by this system the GPS users can get accurate3-dimensional coordinate, velocity and time. During the GPS satellite signals to receivers, the signals will be influenced by multiplex error sources that will reduce the measurement precision. The ionosphere delay error is one of the errors, it caused due to the GPS signals path bending and speed changed when go through the ionosphere that full of free electrons. In the process of ionosphere delay error correction, the GPS users of single frequency receiver commonly used ionospheric model to amend. The Klobuchar Model is a classical model used by the major GPS users, but the correction result is not ideal because the limitation of itself. In this paper, the author analyzed this model through measured date by dual frequency receiver, and the analyzed result is same to former scholars’conclusions. Also, the author proposed a new improvement method based on previous analysis. The variability of ionosphere has a serious relation to the Sun’s Activity Intensity, and the Sunspot Relative Number is a symbol reflects the Sun’s Activity Intensity. The new improvement method by means of Sunspot Relative Number to modified Klobuchar model. This improved method has being proved a large scale promotion to correction effect through experimental date. Dual frequency receiver can receive two signal frequencies, so it can amend first-order term of the ionosphere delay error through the relationship of signal frequency and the error. This method by two frequencies can reach a high precision that centimeter-scale precision. With the beginning of the GPS modernization, the GPS satellites start to launch the third carrier frequency. This step makes the possible of the correction of second-order term of the ionosphere delay error through triple-frequencies. Based on the derivation of two order correction, the author considered the variable θ that the influence during the error correction. Through analysis, we get an angle that can reach millimeter-scale precision in the process of triple-frequencies correction.