Level-1 Algorithm Overview

The SENTINEL-1 Payload Data Ground Segment (PDGS) is responsible for:

  • implementing the SENTINEL-1 mission observation scenario
  • X-band data reception
  • generating the operational core ground segment products
  • reacting to emergency orders with rush instrument tasking and processing
  • providing access to SENTINEL-1 data
  • ensuring long term mission data archiving
  • monitoring the instrument and mission performance
  • ensuring SENTINEL-1 core operational user products meet the expected quality, with necessary calibration and validation activities.

Within the PDGS, the Instrument Processing Facility (IPF) is responsible for the generation of Level-1 and Level-2 products. In addition to SENTINEL-1, the IPF uses the same processing system and mostly the same algorithms for processing of ENVISAT ASAR stripmap and wave mode data. Level-0 data from SENTINEL-1 and ENVISAT ASAR are ingested into the system where different pre-processing steps are performed for the respective mission data. The system then applies the Single Look Complex (SLC) image processing for Doppler centroid estimation and focusing, as well as mode-specific processing for assembling of multi-swath products. The Level-1 post-processing then generates the output Level-1 SLC products and the Level-1 Ground Range Detected (GRD) products. From internally generated Level-1 SLC and GRD products, the Level-2 Ocean (OCN) products are produced.

Level-1 Algorithmic Overview


To accomplish this, the IPF is composed of several software components as shown in the following figure.

SENTINEL-1 IPF Architecture


The algorithms applied by the IPF to generate Level-1 products from Level-0 data include:

Processing of each polarisation is essentially the same. A separate image is generated for each polarisation, and polarisation-specific correction and calibration factors are applied during the processing of each polarisation The Doppler Centroid (DC) from the co-polarisation channel is used for processing both polarisations, so that the two resulting images are accurately co-registered.

For further details on the SENTINEL-1 Level-1 algorithms, please refer to the SENTINEL-1 Level-1 Detailed Algorithm Definition document (S1-TN-MDA-52-7445).

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