14-Feb-2012

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Generic Processor

Systematic processing in NRT
On request processing
From ERS-1/2 SAR processor to Envisat ASAR processor
System design for stripline processing
Floating scene frame concept
Envisat processing requirements
ASAR generic processor functional block diagram

The ASAR generic processor is developed for near real time (NRT) and off-line processing by MDA as subcontractor of THOMSON.

Systematic processing in NRT

Regional mission

Systematic generation of medium resolution products for IM, AP, and WS, with processing in stripe
Systematic generation of browse products with processing in stripe

Global mission

Systematic generation of wave mode products (Level 1B)
Systematic generation of global monitoring mode products (Level 1B) in stripe

On request processing

Processor is designed to handle a number of on request high resolution products/orbit (image mode, alternating polarisation mode).

From ERS-1/2 SAR processor to Envisat ASAR processor

Use of ASAR generic processor

-simplification of processor and product validation
-products compatibility
-phase preserving processor (interferometry)

Precise ESA product/processing specification

Processing in stripe for the products generated systematically

-provides no discontinuity geometrically and radiometrically (image geometric and radiometric requirements applicable to the complete segment)

System design for stripline processing

Fulfillment of throughput requirement and scalability to processor node performance.

Floating scene frame concept

For products processed systematically in stripe, the user selects the position of one or more scenes along the acquired data segment. The scene starts at granule boundary.

For products generated on request (alternating polarisation and image modes precision products), the user can select a SCENE starting from any time along the acquisition data segment (no framing constraint).

Envisat processing requirements
(as per PO-RS-ESA-GS-00245 issue 3.2 - 23 April 1996 Image Quality Parameter)

IMAGE QUALITY PARAMETER	ENVISAT ASAR SINGLE BEAM	ENVISAT ASAR SCANSAR
RANGE IRF	< 10%	< 10%
AZIMUTH IRF	< 10%	< 10%
PSLR degradation	< 2 dB	< 2 dB
ISLR degradation	< 2 dB	< 2 dB
Doppler Centroid Accuracy	50 Hz	25 Hz
Radiometric Error	< 0.1 dB	< 0.2 dB
Point Target Linearity	> 0.97	> 0.97
Absolute Location accuracy	< 2 pixel lengths	< 2 pixel lengths
Geometric misregistration	< 0.5 pixel lengths	< 0.5 pixel lengths
CEOS phase preserving TEST	phase s.d.< 5.0 d. phase mean< 0.1d. no discontinuity ASAR_IMS & WV1	phase s.d.< 5.0 d. phase mean<0.1d. no discontinuity ASAR_APS
Point target Phase error TEST	< 0.1 degrees ASAR_IMS & WV1	< 0.1 degrees ASAR_APS

ASAR generic processor functional block diagram

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry