精密测距测速系统(PRARE)是由德国发展的双频双程微波卫星跟踪系统，其空间部分搭
载在欧洲航天局(ESA)的第二颗资源遥感卫星ERS--2上并正常运行至今。该系统具有
全天候、全自动、台站便于流动、数据多等特点。其高精度的跟踪信息可用
于ERS--2的定轨以及某些大地测量与地球物理参数的确定。其双频特性可用于电离层方面的研究。
另外，PRARE还可用于精确的时钟同步。详细介绍了PRARE的发展、构成、测量原理、性
能以及国际上利用PRARE资料所开展的工作，展望了PRARE在我国的应用研究前景。
Research and Applications of PRARE
Zhang Feipeng Huang Cheng Zhang Zongping
(Shanghai Astronomical Observatory, The Chinese Academy of Sciences, Shanghai 200030)
Abstract
PRARE (Precise Range And Range Rate Equipment ) is a space-borne, two-way,
two-frequency microwave tracking system which has been developed in
Germany. Since April 21, 1995 the system has been working well onboard the
second ESA European remote sensing satellite ERS-2. PRARE can operate
automatically in all weather conditions. Thus, PRARE has more abundant
data than SLR. Moreover, the ground stations, which are small in size and
highly mobile, operate almost without man's control. The precise tracking
information is used to derive preliminary and precise ERS-2 orbits as well
as other geodetic/geophysical parameters like Earth orientation, station
coordinates or Earth gravity field model. The two-frequency down-link
measurements are used to correct the ionospheric influences on the signals
and to monitor the total electron content $C_{\rm TEC}$ of the ionosphere.
Additionally, it has been proved that PRARE can be used for precise clock
synchronization.
The paper introduces the development, the components, the measurement
principle and the performance of PRARE in detail, gives retrospect of the
research work on PRARE which had been doing by some international institutes,
and reviews the prospects of PRARE applications in China.
Key words Precise Range And Range Rate Equipment (PRARE)---Satellite geodesy---microwave
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