星载高精度测距与时间同步技术研究

发布时间：2018-04-03 22:02

本文选题：星间链路　切入点：通信测距一体化　出处：《中国科学院国家空间科学中心》2017年博士论文

【摘要】：本论文的研究内容的项目背景,是某绕月低频干涉测量卫星编队项目。通信、测距、时间同步(Communication,RangingSynchronization,CRS)是卫星编队进行干涉测量的前提条件,被视为有效载荷协同工作领域的关键技术之一。根据本论文的调研工作,有比较多的星间链路实现了通信功能,也有比较多的项目实现了非常高精度(200km距离达到1~2mm精度)的星间测距,较高精度的时间同步(优于1ns,现处于研究阶段)。但是,这些功能的实现,都还只是单一的功能,不能够在单一的射频链路上,同时完成完整的CRS功能。本论文所依托的项目,对卫星的体积、重量、功耗等都有严格的限制,同时,CRS设备还需要受到飞行器轨道、功耗等限制条件,不能够采用GNSS授时、温控等技术提高测量和后处理的精度。本文重点研究了同时满足上述约束要求的CRS一体化的星间链路方案,该项目的CRS系统需要达到的指标为:1~10km距离下,同时完成1Mbps信源速率的传输,1m的测距精度和3.3ns的时间同步精度。本论文首先研究了一体化CRS技术的信号体制:采用可以兼具数传、测距一体化的GMSK+PN(Gaussian Filtered Minimum Shift Keying+Pseudo Noise)调制。它可以在兼顾高码率数传的条件下,完成较高精度的测距和时间同步,本文对此种调制解调方式的调制参数的设置、数传信号解调、测距信号分离和测距信号解调等进行了深入研究。本论文提出了一体化CRS技术在提供同步的、低抖动的参考时钟源的过程中,分成测量和驯服两步走的策略。测量精度是满足任务精度要求的前提,本文明确了双向单程伪距测量(Dual One Way Ranging,DOWR)的原理、对测量的各种误差源,进行了建模分析,并根据模型,对各种误差消除的技术进行了分析比较,得到了本技术在现有条件下,最终可以达到的性能极限。一体化CRS技术的测量得到的距离和时差信息,需要经过滤波后处理算法,才可以得到最终的距离,通过驯服算法,得到高精度、低抖动的参考时钟信号。本文对上述后处理算法,进行了深入研究。
[Abstract]:The project background of this thesis is a satellite formation project of low frequency interferometry around the moon.Communication, ranging and time synchronization (CRS) is a prerequisite for satellite formation interferometry, and is regarded as one of the key technologies in the field of payload cooperative work.According to the research work of this paper, more intersatellite links have realized the communication function, and many projects have realized the intersatellite ranging with very high precision (200km distance to 1~2mm precision).High precision time synchronization (better than 1 NS) is now in the research stage.However, the implementation of these functions is only a single function, can not be on a single RF link, complete CRS functions at the same time.The project supported in this paper has strict limits on the volume, weight and power consumption of the satellite. At the same time, the CRS equipment also needs to be restricted by the orbit and power consumption of the aircraft, so it can not be used for GNSS timing.Temperature control and other techniques to improve the accuracy of measurement and post-processing.In this paper, we focus on the intersatellite link scheme of CRS integration, which meets the requirements mentioned above. The CRS system of this project needs to reach the target of 10 km distance.At the same time, the ranging accuracy of 1Mbps source rate and the time synchronization accuracy of 3.3ns are achieved.In this paper, we first study the signal system of integrated CRS technology: GMSK PN(Gaussian Filtered Minimum Shift Keying Pseudo Noise, which can be integrated with digital transmission and ranging, is adopted.It can achieve high precision ranging and time synchronization under the condition of taking into account the high bit rate digital transmission. In this paper, the modulation parameters of this modulation and demodulation mode, the digital signal demodulation,The separation of ranging signals and demodulation of ranging signals are studied in depth.This paper proposes a two-step strategy of measuring and taming the integrated CRS technology in the process of providing a synchronous, low-jitter reference clock source.The measurement accuracy is the prerequisite to meet the requirement of task precision. This paper clarifies the principle of dual One Way angling DOWR (dual One Way ranging DOWR), analyzes the error sources of the measurement, and analyzes the error sources according to the model.By analyzing and comparing the techniques of error elimination, the performance limits of this technique can be achieved under the existing conditions.The distance and time difference information obtained by integrated CRS technology need to be filtered and processed before the final distance can be obtained. The reference clock signal with high precision and low jitter can be obtained by taming the algorithm.In this paper, the post-processing algorithm is studied.
【学位授予单位】：中国科学院国家空间科学中心
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P228

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