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ASAR Data Formats Products
Geolocation Grid ADSRs
Doppler Centroid parameters
Chirp parameters
Antenna Elevation pattern
ASAR external characterization data
ASAR external calibration data
Level 0 SPH
Level 0 MDSR
SPH for auxiliary data with N=1 DSDs
Wave Mode Geolocation ADS
ASAR Wave Mode Products Base SPH
Slant Range to Ground Range conversion parameters
Measurement Data Set containing spectra. 1 MDSR per spectra.
Ocean Wave Spectra
Map Projection parameters
ASAR Image Products SPH
Measurement Data Set 1
Auxilliary Products
ASA_XCH_AX: ASAR External characterization data
ASA_XCA_AX: ASAR External calibration data
ASA_INS_AX: ASAR Instrument characterization
ASA_CON_AX: ASAR Processor Configuration
Browse Products
ASA_WS__BP: ASAR Wide Swath Browse Image
ASA_IM__BP: ASAR Image Mode Browse Image
ASA_GM__BP: ASAR Global Monitoring Mode Browse Image
ASA_AP__BP: ASAR Alternating Polarization Browse Image
Level 0 Products
ASA_WV__0P: ASAR Wave Mode Level 0
ASA_WS__0P: ASAR Wide Swath Mode Level 0
ASA_MS__0P: ASAR Level 0 Module Stepping Mode
ASA_IM__0P: ASAR Image Mode Level 0
ASA_GM__0P: ASAR Global Monitoring Mode Level 0
ASA_EC__0P: ASAR Level 0 External Characterization
ASA_APV_0P: ASAR Alternating Polarization Level 0 (Cross polar V)
ASA_APH_0P: ASAR Alternating Polarization Level 0 (Cross polar H)
ASA_APC_0P: ASAR Alternating Polarization Level 0 (Copolar)
Level 1 Products
ASA_IMS_1P: ASAR Image Mode Single Look Complex
ASA_IMP_1P: ASAR Image Mode Precision Image
ASA_IMM_1P: ASAR Image Mode Medium Resolution Image
ASA_IMG_1P: ASAR Image Mode Ellipsoid Geocoded Image
ASA_GM1_1P: ASAR Global Monitoring Mode Image
ASA_APS_1P: ASAR Alternating Polarization Mode Single Look Complex
ASA_APP_1P: ASAR Alternating Polarization Mode Precision Image
ASA_APM_1P: ASAR Alternating Polarization Medium Resolution Image product
ASA_WSS_1P: Wide Swath Mode SLC Image
ASA_WVS_1P: ASAR Wave Mode Imagette Cross Spectra
ASA_WSM_1P: ASAR Wide Swath Medium Resolution Image
ASA_APG_1P: ASAR Alternating Polarization Ellipsoid Geocoded Image
Level 2 Products
ASA_WVW_2P: ASAR Wave Mode Wave Spectra
ASAR Glossary Terms
Sea Ice Glossary
Land Glossary
Oceans Glossary
Geometry Glossary
ASAR Instrument Glossary
Acronyms and Abbreviations
ASAR Frequently Asked Questions
The ASAR Instrument
Instrument Characteristics and Performance
Inflight Performance Verification
Preflight Characteristics and Expected Performance
Instrument Description
Internal Data Flow
ASAR Instrument Functionality
Payload Description and Position on the Platform
ASAR Products and Algorithms
Auxiliary Products
Common Auxiliary Data Sets
Auxiliary Data Sets for Level 1B Processing
Summary of Auxiliary Data Sets
Instrument-specific Topics
Level 2 Product and Algorithms
Level 2 Product
ASAR Level 2 Algorithms
Level 1B Products
ASAR Level 0 Products
Level 0 Instrument Source Packet Description
Product Evolution History
Definitions and Conventions
Organisation of Products
ASAR Data Handling Cookbook
Hints and Algorithms for Higher Level Processing
Hints and Algorithms for Data Use
ASAR Characterisation and Calibration
The Derivation of Backscattering Coefficients and RCSs in ASAR Products
External Characterisation
Internal Calibration
Pre-flight Characterisation Measurements
ASAR Latency Throughput and Data Volume
Data Volume
Products and Algorithms Introduction
Child Products
The ASAR User Guide
Image Gallery
Further Reading
How to Use ASAR Data
Software Tools
How to Choose ASAR Data
Special Features of ASAR
Geophysical Coverage
Principles of Measurement
Scientific Background
Geophysical Measurements
ASAR Product Handbook
ASAR instrument characterization data
Wave Mode processing parameters
ASAR processor configuration data
Main Processing parameters
ASA_WVI_1P: ASAR Wave Mode SLC Imagette and Imagette Cross Spectra
Product Terms
RADAR and SAR Glossary
Level 1B Products
Summary of Applications vs Products
Site Map
Frequently asked questions
Terms of use
Contact us


2.1.1 Child Products Definition

Child products are the result of the extraction from existing Level 0, Level lB or Level 2 parent products, and they own the same format and file name principles as any other ENVISAT Payload Data Segment (PDS) product (child product does not apply to future products). Also, there is no child product extraction from Auxiliary Data. The child products are generated by the Archiving Facility (ARF) and they consist of one segment, or separated consecutive scenes.

The product structure is provided in the previous section, entitled "Products and Algorithms Introduction"

Each child product contains an integer number of granules, which is a part of the product that corresponds to the time window covered by a Data Set Record (DSR) of the Location Annotation Data Set (LADS). The start time of the granule is the time label of the LADS DSR. For the Advanced Synthetic Aperture Radar (ASAR) instrument, the stop time of the granule immediately precedes the time label of the following LADS DSR in the product.

In table 2.2 below, examples are given for full scenes, relative to the specific product mode described, and scenes the size of only one granule.

Table 2.2 Child product scene sizes
Full Scene Size
Granule Size
100 Km x 100 Km
(10 granules)
10% of the full scene
10 Km along-track
400 Km x 400 Km
(10 granules)
10% of the full scene
40 Km along-track
One imagette for ASAR WV ( one granule )
One imagette for ASAR WV

The Extracted Instrument Header (EIH) product is extracted from a Level 0 product. It contains a suite of Instrument Source Packet (ISP) fields for a selected time interval. Its structure is the following:

  • Main Product Header (MPH): It is identical to the MPH of the Level 0 product from which the data is being extracted, except for the time and positioning information which are updated to reflect the extracted region.
  • Specific Product Header (SPH): It contains sensing time information, offset and length in MDS-DSR of each field (one or several fields) extracted from ISP of the parent product.
  • The file name also changes to "C"; that is ASA_IMM_1C. Child Product Extraction Requirements

As was first discussed in the Introduction, the ASAR child product is extracted from a parent product already archived in the ARF. However, the ARF does not archive the child product, and it does not update the inventory. After completion of the instruction, the ARF sends back an instruction report to the Centre Monitoring and Control (CMC).

The ASAR child products extraction criteria is defined as follows:

Table 2.3 ASAR child product extraction criteria
Product Level




Data Set

Extracted Ins. Header
Level 0 Yes Yes No No Yes
Level 1B and Level 2 Yes Yes No Yes N/A Data Set Selection

The ARF shall select the Data Set (DS) of the parent product based on data set names in each Data Set Descriptor (DSD) of the Specific Product Header (SPH) to extract child products with a DS extraction criterion. All Global ADS (GADS) shall be kept in the child product. ISP Subsets Selection (Extracted Instrument Headers)

The ARF shall extract from the Level 0 products the Extracted Instrument Headers (EIH) , by selection of one or several sets of selected Instrument Source Packets (ISPs). Common Archiving Facility Requirements

  1. The external auxiliary data DSD records shall always be kept in the child product.
  2. The GADS shall always be kept in the child product.
  3. The MPH of the extracted child product shall be copied from the parent product, and then updated with the following parameters:
    • sensing start day and start time (t0)
    • sensing stop day and stop time (TL)
    • duration of the product (t 140)
    • processing centre
    • processing time
    • total size
    • size of each DS
    • number of DS
  4. The name of the extracted child product shall be updated according to the parameters updated in the MPH.
  5. The SPH shall be copied from the parent product.
  • Time information.
  • Location information of the products determined by reading the LADS in Level 1B or Level 2 products, if the product has a LADS. This information contains at least the four corners of the product area expressed in latitude and longitude, including the first and last sample latitude and longitude (determined from the LADS).

The following parameters shall be updated for each DSD describing a data set in the extracted child product:

  • filename: set to "NOT _USED" if the DS corresponding to the DSD is empty, when the DS is not kept during a data set extraction
  • data set offset
  • total size of data set
  • number of DSRs within the data set