8/6/2019 DORIS - Doppler Orbitography and Radio Positioning Integrated by Satellite

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T

he DORIS system, de-signed and developed by

the CNES (the FrenchSpace Agency), in collaboration

with GRGS (Space Geodesy Re-search Group) and IGN (FrenchGeographic Institute), has a du-al purpose.

This dual capability has en-abled DORIS to be used in nu-merous applications since 1990.The system is used in ocean orice field altimetry missions suchas Topex/Poseidon, studies ofthe shape and movements of theEarth, as well as many locationservices where different satel-lites are equipped with the DO-RIS receiver. Operational sincethe launch of the remote sens-ing satellite SPOT-2, this systemis used to determine the positionof the satellite to within 10 cmin realtime, and about 1 cm af-ter ground processing. The sys-

tem also measures and calculatesthe ionospheric correction. Ac-

curate knowledge of satellitesorbits is essential for altimetrymissions that measure sea level.This monitoring of the oceans isa major objective for the scien-tific community. Rises in sea lev-el due to the potential effects ofglobal warming could have disas-trous consequences for many ar-eas in the world.

Reference pointstations

To be able to accomplish thesemeasurements, the DORIS sys-tem is using a network of about60 ground stations as referencepoints on Earth. Each of these ref-erence point stations is equipped

with the Vaisala Combined Pres-sure, Humidity and TemperatureTransmitter PTU200, providingaccurate local reference data on

all of these parameters at the in-stallation site. On the satellite, an

antenna pointed towards Earthreceives radio waves emitted byground stations in the DORISnetwork. An electronic receiv-er measures the frequency shiftcaused by the Doppler effect.

During 2000-2002, Vaisalahas delivered approximately 70PTU200 transmitters to the Tou-louse-based company S.M.P., amajor international provider ofsatellite communication systems,data transmission, data process-ing (Telecommand, Telemetry andcontrol) and microwave products.S.M.P. has integrated the trans-mitters into their own aforemen-tioned reference stations.

Three-in-onemeasurement

The PTU200 transmitter is a ma-ture, well field-proven product,

which combines three measure-ment parameters: pressure, tem-

perature and humidity. The ap-plications of the PTU200 rangefrom calibration laboratory en-vironmental condition monitor-ing, to laser interferometer ac-tive wavelength compensation,and GPS meteorological mea-surements. The PTU200 trans-mitters are available with one ortwo pressure transducers. Threedifferent kinds of sensor headscan be used with the PTU200.The transmitters use a RS232 orRS485 serial interface and theyare also available with a local dis-play. In outdoor applications, itis recommended to use the PTU-200MIK Outdoor InstallationKit. In addition, a mounting tri-pod is available for temporaryfield installations.

PeterErikssonAccountDirectorVaisalaParis,France

DORIS-DopplerOrbitographyandRadiopositioningIntegratedbySatellite

The DORIS system.Vaisala Combined Pressure, Humidity and Temperature TransmitterPTU200.

DORIS is a Doppler satellite tracking system developed forprecise orbit determination and precise ground location.