DORIS系统概述

Doris, the space surveyor

The Doris system is a french civil precise orbit determination and positioning system. It is based on the principle of theDoppler effect with a transmitting terrestrial beacons network and onboard instruments on the satellite's payload (antenna,radio receiver and oscillateur ultra-stable). DORIS，空间测量员

DORIS系统是法国民⽤精确定轨定位系统。它是基于地⾯信标传输⽹络和卫星的有效载荷（天线，⽆线电接收器和超稳定振荡器）之间的多普勒效应这⼀原理。

Doris is one of three systems used for precise determination of the Jason-1 satellite's orbit. Several of these techniques aresometimes merged on the same satellite : Jason-1 satellite includes three tracking systems, Doris, location by GPS and lasertelemetry. The Doris system perfectly corresponds to the specifications required for the ocean's topography observations andthe amplitude of the observed phenomena: it is now enables to measure the satellite position on its orbit close to 1 cm. It isinteresting to compare this precision with the precision obtained at the beginning of the space age, where the the satelliteposition was estimated close to 20 km then close to 20 meters in the 80's. Since 1998, the Diode navigator has added real-time measurement processing capability for satellite navigation.

DORIS系统是Jason-1卫星上使⽤的三⼤精确定轨系统之⼀。这些技术有时在同⼀颗卫星上被整合：Jason-1卫星包括3个追踪系统，DORIS系统，并且由GPS（全球定位系统）和激光遥测技术实现定位。DORIS系统完美地对应于海洋地形测量所需要的规格和观测现象的振幅：现在它能够测量卫星的轨道接近1厘⽶。将这个精度与太空时代的初期获得的精度进⾏⽐较是很有趣的，太空时期初期估算的卫星位置是接近20km，到了⼋⼗年代则是接近20m。从1998年开始，Diode导航仪为卫星导航添加了实时测量处理功能。Principle

How does Doris work? The Doris system is based on the principle of the Doppler effect. It is a system optimized for orbitdetermination with extreme precision, global coverage and all-weather measurements.原理

DORIS系统是如何⼯作的？DORIS系统是基于多普勒效应这⼀原理的。它是⼀个⾼精确度、覆盖全球的、全天候测量的最佳化定轨系统。System

Details on Doris instrument which is part of the satellite payload, on terrestrial stations, on control and processing center andon system enhancements.系统

设备或功能的详细说明：作为卫星有效负载的⼀部分的DORIS设备、地⾯站设备、控制处理中⼼以及系统增强功能。Doris applications

In addition to its functions in orbitography, Doris as a space surveyor is also a terrestrial positioning system that has foundmany applications in geodesy and geophysics.DORIS系统应⽤

除了在定轨⽅⾯的功能，作为⼀个太空测量员的DORIS系统同样是⼀个地⾯定位系统，在测地学和地理学上得到了很多的应⽤。

doris missions

With more satellites carrying the Doris instrument, the system will make more accurate than before.DORIS系统的任务

随着越来越多的卫星携带DORIS系统设备，这个系统会⽐以前的精确度更⾼。

Locating a satellite or a point on Earth involves calculating positional coordinates (and possibly velocities) in three

dimensions within a given reference frame. Obviously, this frame is Earth-fixed since our aim is to use precise positioningdata to study the oceans, crust, ice and other features. The origin of the reference frame is the Earth's center of mass, orgeocenter.

Locating a satellite in space is complicated by the fact that it is in motion on a trajectory dictated by launch parameters andforces acting on the satellite. Chief among these forces are the pull of Earth's gravity, which keeps the satellite in orbit, andsurface acceleration forces such as solar radiation pressure and atmospheric drag. That is why we need a good

understanding of the Earth's gravity field and the satellite's environment to calculate the real trajectory with respect to theelliptical orbit described by Kepler's laws of motion. Lastly, positioning also relies on geodetic observation techniques.Doppler effect定位原理

对在轨卫星实现精确定位的能⼒是测⾼数据质量⾼低的关键因素。基于多普勒效应的DORIS系统有助于精致的轨道测定。给卫星定位或者在地球上标识某个点涉及到在给定的三维参考坐标系中进⾏位置坐标的计算。显然，由于我们的⽬的是使⽤这些精确的定位数据研究海洋、地壳、冰⼭和其他特征群，所以这个框架是随地球固定的。参考坐标系的原点是地球的质⼼。在太空中的卫星定位是复杂的，事实上，卫星是沿着由其发射参数和推⼒设置决定的轨道运⾏的。在这些推⼒中主要是地球引⼒，使得卫星在轨道上运动，另外就是地⾯加速⼒，譬如太阳辐射压⼒和⼤⽓阻⼒。这就是考虑开普勒运动定律中描述的椭圆轨道的情况下进⾏实际轨道的计算时，我们需要对地球重⼒场和卫星的外界环境有极为透彻理解的原因。另外，定位同样依赖测地观测技术。

The Doris antenna onboard satellites receives signals emitted by the terrestrial stations network. When the receiver and thesource are moving each other, the receiving wavelength differs from the emitting wavelength : it is the Doppler effect.When the satellite moves closer to the emitting beacons, the frequency of the signal received by Doris instruments onboardthe satellite is higher than one of the emitted signal, and lower when it

moves away. If the emitting and receiving frequencies are equal, the emitting beacon is on the perpendicular to the satelliteground track. On a plot of the frequency received by the satellite as a function of time, the slope of the curve at the point ofnear maximum (TCA point: Time of Closest Approach) enables to calculate the distance between the beacon on the groundand the transmitting satellite.多普勒效应

DORIS系统的卫星机载天线接受来⾃地⾯信标⽹发射的信号。当接收天线和发射天线之间存在相对运动时，接收到的波长会不同于发射波长：这就是多普勒效应。

当卫星向着发射信号灯运动时，卫星的机载设备接收到的信号频率会⾼于发射频率，相反远离时就会低于发射频率。如果发射频率和接收频率相等，发射信号灯垂直于卫星地⾯轨迹。把卫星接收到的⼀系列频率作为时间函数，曲线最⾼点处（TCA点：时间最接近）的斜率能够计算出地⾯信号灯和传递卫星之间的距离。

The orbit calculation

The precise orbit determination is not instantaneous. It requires measurements processing and the taking into account ofenvironmental satellite (maneuvers, the physical forces of gravity and forces of atmospheric friction ...). The orbit is calculatedby adjusting a model by minimizing differences between the measurements velocities obtained by Doris and those predictedby the model. The accuracy of this calculation increases with the accumulation of measurements so with the time : the

accuracy is 10 cm RMS on the radial orbit for data up to three hours, 4 cm RMS for data up to three days, and 2.5 cm for dataup to 30 days, with the goal to minimize it closer to 1cm.轨道计算

精确定轨不是瞬时的，它需要测量过程，把周围环境中的卫星（军事演习，地球引⼒和⼤⽓摩擦⼒）考虑进去。通过最⼩化DORIS系统获得的测量速度和模型的计算值之间的差距，进⽽修正这个模型实现轨道的计算。计算的准确度随着时间和测量值的积累增加：以均⽅根来表⽰精确度，达到4个⼩时的数据其精确度是10厘⽶，达到3天的数据其精确度是4厘⽶，达到30天的数据其精确度是2.5厘⽶，其⽬的是尽量使它接近1厘⽶。

High-precision positioning

When the satellite position is precisely determined on its orbit, the Doris system can be used to locate a Doris ground beaconwhich is outside the reference network, at a point requiring temporary monitoring (volcanoes, geological faults, glaciers ...).This system is suitable for objects fixed or moving very slowly and is useful in the geophysics and geodesy fields (See Othergeophysical applications).⾼精度定位

当卫星被精确地定轨后，DORIS系统能为参考⽹络之外的DORIS地⾯信号灯进⾏定位，这些定位点在某些时候需要临时的监控（⽕⼭，地震，冰河…）。这个系统适合于固定的物体或者是运动及其缓慢的物体，对地理学和测地学同样⾮常有⽤（参见其他的地理应⽤）。Doris system

The Doris system includes all the instruments onboard the carrying satellite (antenna, receiver, oscillator), an internationalnetwork of autonomous stations spread around the globe and a control and processing center that calculates the orbit of thesatellites.DORIS系统

DORIS系统包括所有的星上设备（天线，接收机，振荡器），⼀个由覆盖全球的⾃主地⾯站组成的国际⽹络和⼀个进⾏卫星轨道计算的控制处理中⼼。

Whether onboard satellites or on the ground stations network, the efficacy of the system has evolved over the years toachieve a precision up to the centimeter with Jason-1. The integration of

Diode, software that calculates real-time location and very precise velocity of the satellite, marked a milestone advance.不论是星上设备还是地⾯站⽹络，这⼏年来DORIS系统的功效已经逐步演化并且达到了Jason-1系统的厘⽶的精确度。对Diode这⼀计算卫星即时位置和⾼精度速度的软件的集成，标识着⼀个⾥程碑似的进步。Instruments onboard

The Doris instrument is part of the satellite payload. It comprises a MVR receiver that measures radial velocity, anomnidirectional antenna and an ultrastable oscillator.星上设备

DORIS系统的星上设备是卫星负载的⼀部分。它包括⼀个测量径向速度的MVR接收机，⼀个全向天线，⼀个超稳晶体振荡

器。

Ground beacons

The Doris system now includes about 60 stations spread around the globe, in an international network of autonomousstations used as reference points on the ground to cover the satellites trajectory continuously.地⾯信标

⽬前，DORIS系统包括分布于全球的约60个地⾯定轨信标站，这些信标站处于⼀个⾃主地⾯站的全球⽹络当中，这些⾃主地⾯站被作为连续覆盖卫星轨道的地⾯参考点。Control and processing center

The data are relayed to the ground on each pass of the satellite over a station. Then they are sent to Ssalto at reguliarinterval, the Doris mission control centre.控制处理中⼼

卫星每经过⼀个地⾯站，数据就被转发到地⾯。然后这些数据以有规律的频率被送到DORIS 任务控制中⼼Ssalto。A system constantly evolving

Whether onboard satellites or on the ground stations network, the efficacy of the system has evolved over the years toachieve a precision up to the centimeter with Jason-1.不断演变的系统

不论是星上设备还是地⾯站⽹络，这⼏年来DORIS系统的功效已经逐步演化并且达到了Jason-1系统的厘⽶的精确度。Diode

Diode is a software integrated in the Doris instrument that calculates on-board very precise real-time location and velocity ofthe satellite.Diode

在DORIS系统的设备中，Diode是⼀个整合的软件，这个软件⽤于机载计算卫星的即时位置和速度。Doris applications

The Doris system was primarily designed for the precise orbit computation required for observing the oceans by altimetry.The Diode navigator enables to provide the precise satellite position on its orbit in real time.

Doris unique network of ground stations and its highly accurate positioning capability have also proven greatly valuable forgeodesy and geophysics applications : measuring the continental drift, fitting the local geodesical network, monitoring thegeophysical deformations, determining the rotation and the gravity parameters of the Earth and contributing to theinternational reference system.DORIS系统的应⽤

DORIS系统最初是为了满⾜在测⾼学上观察海洋的要求进⾏精确的轨道计算⽽设计的。Diode导航仪能够提供即时的卫星精确轨道位置。

DORIS系⼀⽆⼆的地⾯站⽹络和⾼精度的定位能⼒，在地理学和地理学应⽤⽅⾯同样具有重⼤的价值：测量⼤陆的漂移，装配局部的地理⽹络，监控地理变形，确定地球⾃转和重⼒参量，促进国际参考系统的形成和完善。

See our applications:

Orbitography

Precise orbit for Topex/Poseidon, Jason-1, Spot, Envisat.Mean sea level

Earth gravity field

Tracking the Earth's centre of gravity.

Doris sees the seasons weighing on the Earth.

Earth rotation

Earth's shifting poles.

Precise positioning

Contributing to the International Reference System Measuring continental driftMystery in Socorro...Measuring a glacier's drift

Navigation

Time tagging