The Reaserch Of The Transit Influence In Transfer Ranging Measurement And Orbit Determination

In the same way as the natural planetary satellites，the man-made satellites presentphenomena such as occultation，eclipse and transit。When the transiting satellite isbetween the antenna of the ground station and the sun in a straight line, theelectromagnetic waves produced by the sun are within the range of the antenna beams.Radiating wide spectrum of electromagnetic waves, the sun is a huge source of noise，and the temperature of the solar radio noise can be over10000K, thus seriouslyinterfering with the satellite signals received by the antenna. The transponder rangingsystem is a high-precision ranging system by means of two-way satellite time andfrequency transfer (TWSTFT)，and its accuracy will be affected by the satellitestransiting across the sun.In this paper, the computer program to calculate the time of the solar transit based onhigh-precision DE405ephemeris are designed and implemented. Using this program，the result of the time of the solar transit and the effect of ranging data by the solartransit are also calculated.The conclusion as follows:The effect of solar transit on ranging data is obvious. More noises in thecommunications channels lead to higher bit error rate, and the increased errors of thereceived data are presented as obvious hoppings and abundant wild values.On the satellite with the110°longitude of the sub-satellite point, the shift in the orbitis about1meter, far less than the error caused by the noises. The noise errors causedby solar transit depend on the location of the ground station. Among the only fourground stations with transponder ranging system, Kun-ming Station is most heavilyaffected.Compared with other stations, Kun-ming Station only experiences short but intenseeffects from the solar transit, without much daily fluctuation. Xi-an station，the secondmost affected station, is affected for longer than Kun-ming Station, but the intensityof the effects always increase firstly and then decrease gradually.Since the geographic longitude of Xi-an station is closed to Satellite-1’s longitude ofthe sub-satellite point, the effects of solar transit cause larger error of Satellite-1thanof Satellite-4at Xi-an station.Meanwhile, the geographic longitude of Ke-shi station is closed to Satellite-4’slongitude of the sub-satellite point, so the effects of solar transit cause larger error ofSatellite-4than of Satellite-1at Ke-shi station. Changchun station is affected the least by solar transit, where the maximum orbitalerror caused by solar transit is bigger than20meters. In the three directions of RTN,the N direction is affected the most.