@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix ns0: <http://gcmd.gsfc.nasa.gov/kms#> .

<https://gcmd.earthdata.nasa.gov/kms/concept/9bfd9ff7-b838-4834-bd47-0127384c79f7>
  skos:changeNote """2019-03-26 16:44:06.0 [sritz]  
update WeightedRelation (Platform-Instrument); 
update WeightedRelation (1); 
""", """2019-03-26 16:43:29.0 [sritz]  
insert WeightedRelation (id: null
related concept uuid: 41163801-6aac-43e5-aed7-9f52613a6a73
relationship type: null
relationship value: null
generated by: null); 
""", """2019-02-22 14:20:26.0 [mmorahan]  
update Resource (image); 
insert WeightedRelation (id: null
related concept uuid: 5449d87b-5573-450f-8acb-2fdfeab3c8ce
relationship type: null
relationship value: null
generated by: null); 
""" ;
  skos:broader <https://gcmd.earthdata.nasa.gov/kms/concept/7561d126-2baf-4583-a6cc-f8159ebf8e94> ;
  skos:inScheme <https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/instruments> ;
  a skos:Concept ;
  skos:definition """[Source: ESA/Earthnet Online, 
http://envisat.esa.int/instruments/doris/ ]

The Doppler Orbitography and Radio-positioning Integrated by Satellite instrument is a microwave tracking system that can be utilized to determine the precise location of the ENVISAT satellite. Versions of the DORIS instrument are currently flying on the SPOT-2 and Topex-Poseidon missions.

DORIS operates by measuring the Doppler frequency shift of a radio signal transmitted from ground stations and received on-board the satellite. The reference frequency for the measurement is generated by identical ultra-stable oscillators on the ground and on-board the spacecraft.

Currently there are about 50 ground beacons placed around the globe which cover about 75% of the ENVISAT orbit. On board measurements are performed every 7 - 10 seconds. Precise Doppler shift measurements are taken using an S-band frequency of 2.03625 GHz, while a second VHS band signal at 401.25 MHz is used for ionospheric correction of the propagation delay.

On the ground, DORIS data is used to create precise orbit reconstruction models which are then used for all satellite instruments requiring precise orbit position information. In addition, DORIS operates in a Navigator mode in which on-board positioning calculations are performed in real-time and relayed to the ground segment. 


Group: Instrument_Details
   Entry_ID: DORIS
   Group: Instrument_Identification
      Instrument_Category: Earth Remote Sensing Instruments
      Instrument_Class: Passive Remote Sensing
      Instrument_Type: Positioning/Navigation
      Instrument_Subtype: Radio
      Short_Name: DORIS
      Long_Name: Doppler Orbitography and Radiopositioning Integrated by Satellite
   End_Group
   Group: Associated_Platforms
      Short_Name: CRYOSAT-2
      Short_Name: ENVISAT
      Short_Name: JASON-1
      Short_Name: OSTM/JASON-2
      Short_Name: SPOT-2
      Short_Name: SPOT-3
      Short_Name: SPOT-4
      Short_Name: TOPEX/POSEIDON
      Short_Name: SPOT-5
      Short_Name: CRYOSAT
   End_Group
   Group: Spectral_Frequency_Information
      Wavelength_Keyword: Radio
      Number_Channels: 2 Channels
      Spectral_Frequency_Coverage_Range: 401.25 MHz and 2036.25MHz
   End_Group
   Online_Resource: http://envisat.esa.int/instruments/doris/
   Online_Resource: http://www.aviso.oceanobs.com/en/doris/index.html
   Sample_Image: http://www.aviso.oceanobs.com/typo3temp/pics/98d5269f70.jpg
   Creation_Date: 2007-04-16
   Group: Instrument_Logistics
      Data_Rate: 330 bps
      Instrument_Start_Date: 2002-01-15
      Instrument_Owner: France/CNES
   End_Group
   Group: Instrument_Logistics
      Instrument_Start_Date: 1992-09-23
      Instrument_Stop_Date: 2005-10-09
   End_Group
End_Group"""@en ;
  ns0:altLabel [ ] ;
  ns0:resource [ ] ;
  skos:prefLabel "DORIS"@en .

<https://gcmd.earthdata.nasa.gov/kms/concept/7561d126-2baf-4583-a6cc-f8159ebf8e94>
  skos:prefLabel "Radio"@en ;
  a skos:Concept ;
  skos:narrower <https://gcmd.earthdata.nasa.gov/kms/concept/9bfd9ff7-b838-4834-bd47-0127384c79f7> .