New Regional Satellite Positioning Constellation Scheme Discussion

The characteristics of present “Beidou” satellite positioning system are analyzed. In order to perfect our country regional satellite positioning system, the idea of “Beidou” geosychronous earth orbit （GEO） satellites combined with some middle earth orbit （MEO） satellites constellation is put forward. The details of general satellite constellation optimized method are described, using this method the multiple positioning constellation design results are gained. And those results belong to two type of sehems, one is 2 GEO plus some MEO satellites and the other is 3 GEO plus some MEO satellites. Through simulation and comparison, among those multiple design results, final optimized regional positioning constellation is given. In order to check the chosen constellation cover performance, the position dilution of preeision（PDOP） is calculated, and with ,satellite constellation simulation software Satlab many coverage performances of the chosen constellation substellar point track, elevation, azimuth and visible satellites number changing situation are also simulated.

Analytical solutions for Earth discontinuous coverage of satellite constellation with repeating ground tracks

This paper presents an analytical model for calculating the Earth discontinuous coverage of satellite constellation with repeating ground tracks by integrating and extending the application of coverage region and route theory.Specifically,the visibility condition for a ground point is represented as a coverage region in the two-dimension map of visibility properties,and the trajectories of satellites with circular orbits and repeating ground tracks are converted to several inclined lines in the map.By analyzing the intersections of the lines and the edge of the coverage region,the coverage durations for the ground point can be calculated.Based on the point coverage,the variations of coverage characteristics along the parallel are analyzed,and the regional or global coverage characteristics of constellations can be obtained.Numerical examples show that the proposed method can accurately and rapidly calculate the coverage characteristics,e.g.revisit time and coverage time.The calculated results are extremely close to those of the Satellite Tool Kit(STK)and are also superior to the existing research results.The proposed analytical model can be a useful tool for constellation design and coverage performance analysis.