Mobile version

Doris (Doppler Orbitography and Radiopositioning Integrated by Satellite)

The Doris instrument onboard Swot will provide real-time location and precise orbit determination. Doris measurements are also used for geophysical studies, in particular through the International Doris Service (IDS). Doris is a dual-frequency instrument able to determine atmospheric electron content.

Doppler Orbitography and Radiopositioning Integrated by Satellite (Doris) is a satellite tracking system designed in the late 1980s by Cnes as a new system to provide precise orbits on-board low Earth orbit satellites. The operation of Doris relies on a dense global network of ground stations transmitting omnidirectional signals at a known frequency.

Swot is equipped with the same new-generation (multi-channel and digital) receiver than Sentinel-3, developed by Cnes, as a Customer Furnished Instrument (CFI). This type of receiver is also flying on Jason-2, Jason-3, Saral, HY-2A and Cryosat-2 and is able to track up to seven beacons simultaneously. It was shown that real-time accuracy of the Doris navigation solution (Diode) is about 3.5 cm. Diode is used to drive the open loop tracking mechanism of the nadir altimeter. The offline POD performance is approximately 1 cm on the radial direction (nadir), as for the Jason & Sentinel-3 satellites.

The combination of both GPS and Doris measurements in POD processing improves the final performance on the three directions.

Function

Real-time location: Diode

The Diode onboard navigator locates the satellite on orbit in real time. This information is essential for providing altimetry data in real time or near-real time. 

Doris Diode real-time location is coupled with Poseidon-3B altimeter, thus enabling better altimeter data acquisition in areas like coastal zones, inland waters and ice. 

Precise orbit determination

Doris measurements are used for precise orbit determination (POD).

Ionospheric electron content

By measuring and comparing the path delay of signals transmitted at two separate frequencies, Doris is able to calculate the electron content in the atmosphere. 
This function complements the Poseidon-3 dual-frequency altimeter function.

Principle

Doris orbitography beacons transmit signals at two separate frequencies (2036.25 MHz and 401.25 MHz) to the satellite. The receiver onboard the satellite analyzes the received signal frequencies to calculate its velocity relative to Earth. This velocity is fed into orbit determination models to derive the satellite's position on orbit below 1 centimeter on the radial component.

Further information :

EnglishFrançaisEspañol
Rss feedsContactPartnersFAQLexiconMobile
You must enable cookies in your browser preferences to save the modifications
You are using an older version of Internet Explorer, please update to take full advantage of Aviso+ features

Customize the home page

View all widgets
-->
Reduce display
Public profile
User profile

Select/Deselect widgets

Discover AVISO+

Customizable home, reading tools, products search guide, etc.. Discover step by step the features of the new site AVISO+.

Customizable homepage

The new home page is composed of blocks called "widgets".

Rearrange the blocks with a "Click & Drop".

Hide a widget with the cross at the top right. Reset or add a widget with the "wrench" icon. The "User" and "Public" profiles offer a predefined organization.

All the modifications are automatically saved as cookies on your machine so as to enable you to have your own specific AVISO+.

Reading tools

Ease your reading by choosing the page background colour (black/white) and/or by modifying the font size.

Browsing menu and breadcrum trail

To ease your browsing through AVISO+, you can use at any time the main banner items with the interactive submenus or use the browsing menu on the left side of the screen (it is open by default). For more readiness of the page contents, you can fold and unfold the browsing menu by clicking on the tab. At any time you can know where you are thanks to the browsing menu or the breadcrum at the top of the page.

Products search guide

The first submenu of the "Data" banner item leads you to a new search form enabling you to find quickier the product that suits your needs. The list of results is updated according to your selection criteria.

AVISO+ Multimedia

The first submenu of the "Multimedia" banner item leads you to AVISO+ collections of images and videos linked to altimetry and its applications. Have a nice visit!