3.1.3 Internal Data Flow

ASAR Data Processing

All of the ASAR modes of operation are processed on the ASAR Generic Processor to be installed in the ESA Payload Data Handling Stations (PDHS), at Kiruna and ESRIN-Frascati, and to be procured by the ENVISAT Processing and Archiving Centres (PACs) and national stations offering ESA ASAR services. The use of a generic processor will ensure product compatibility between the different processing centres (same format and processing algorithm) and will simplify product validation.

The ASAR generic processor runs on an IBM SP-2 parallel computer system and is designed to ensure a throughput linearly proportional to the number of processing nodes available in the station.

The key feature of the ASAR Generic Processor is the capability to process acquired data to generate medium-resolution products (150 m) or low-resolution product (1 km), and their corresponding browse products, in Stripline without geometric or radiometric discontinuity.

The ASAR ground processor functional block diagram is shown below in figure3.20 .

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Figure 3.20 ASAR ground processor functional block diagram

ASAR User Services

The access to user services is provided via the Internet and it includes, in particular, a free access to all browse images and the capability to access the data inventory.

The user services allow ordering of products from acquired data and the ordering of future products to be acquired. The on-line retrieval of small products is also possible.

The delivery of products is performed in Near Real Time (NRT) via satellite links and off-line on physical media.

For a full discussion of the ASAR products, and the processes that produce them, refer to the "Products and Algorithms"(Chapter 2. ) section of this handbook.