Study On The Precise Measurement Positioning Between Small Formation Satellites

First，with the continuous development of modern satellite technology, a largevolume of fully functional satellite can no longer meet the cost of the mission,maintainability, and flexible reuse pattern. Second, with the increasing requirements forresolution and sensitivity, to complete the space mission with requirement of highprecision by using one single satellite is inevitably increase the volume of the satellite,complexity and development cost. Therefore, small satellites are proposed to meetmodern space mission under this background. They have the priority of low cost, goodperformance, high reliability, adaptability, short development cycle, etc. But onesatellite’s capability is limited. Multi-satellite formation space mission is verymeaningful. With small satellites technology becoming mature, their advantage isgetting more obvious. They can complete some tasks that are difficult or impossible tofinish for large satellites.In order to achieve precise positioning between the stars, it is particularlyimportant for distributed small satellites to adopt a practical measurement system.Aiming at this, this dissertation studied on several systems for precise measurementpositioning between small formation satellites, including dual-one-way measurementand dual-one-way measurement (KBR), introduced measurements of one-way, KBRmeasurement system’s ranging principle in detail, analyzed its advantages anddisadvantages, and put forward two-way asynchronous non-coherent measurement toimprove its shortcomings. Besides, the key technologies that distributed small satellitescan work together to complete space mission is autonomous satellite navigation. This isthe research focus of all countries. Autonomous satellite navigation’s key point is timesynchronization. Maintaining the satellite space structure relies on the precisionmeasurement of the inter-satellite baseline. Thus increasing the time synchronizationand inter-satellite baseline measurement accuracy are mainly discussed in thisdissertation. In response to these issues, the dissertation presents a method to calculatethe satellite clock error based on the Doppler shift, correcting the satellite clock, improving the time synchronization accuracy and achieving high-precision ranging andspeed measuring. By using MATLAB simulation, proved the method’s feasibility,assesed system’s performance, analyzed all components’ noise impact on measuringprecision, studied on how to eliminate or decrease noise’s effect on mearsuement.Prove this method’s correctness by using MATLBA simulating. The result showsthat the methods of measurement baseline pseudo range measurement values in the longrun time discussed in this dissertation can maintain high accuracy with the worst case ofmeasurement error of1cm, achieving0.1ns-baseline measurement accuracy. Velocityprecision can reach millimeters and the conclusion is consistent with the theoreticaldeduction. Satellite clock face clock difference and the nominal time can be maintainedwithin a certain range with no continuous accumulation. Therefore, this method canprevent the satellite clock drift, and the satellite clocks and ground clock issynchronized to a certain range with no need to exchange clock information with theground station frequently. This method can be used to satellites formation when they areon some deep space missions that the ground station can not monitor.