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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 Products and Algorithms Introduction

Introduction picture
Figure 2.1

The specifications for the standard Advanced Synthetic Aperture Radar (ASAR) data products are shown in table 2.1 below. Many of the product types and definitions are similar to those used for the European Remote Sensing Satellite (ERS). For instance, Precision, Ellipsoid Geocoded, and Single-Look Complex images have the same nominal resolution and pixel spacing as their ERS equivalents. (For a discussion on the differences between resolution and pixel spacing see )

ASAR Measurement Modes

The Advanced Synthetic Aperture Radar is a high-resolution imaging radar that can be operated in 5 distinct Measurement Modes:

Within each mode, several different image swaths may be used. IM, AP, and WS modes are designated as High Rate (HR) modes, and have a downlink rate of 100 Mbps. GM and WV are Low Rate (LR) modes and have a data generation rate of 0.9 Mbps.

In addition, ASAR supports 2 Auxiliary Modes (Test Mode and Module Stepping Mode ) and one Calibration Mode (External Characterisation Mode ), which are used for testing, calibration and instrument monitoring.

Table 2.1 Standard specifications for ASAR data products
Product ID Product Name

Nominal Resolution(m)

(range x azimuth)

Nominal Pixel Spacing (m)

(range x azimuth)

Approx.Coverage (km)

(range x azimuth)

Equivalent No. of Looks
Image Mode Precision
30 x 30
12.5 x 12.5
56-100 x 100
> 3
Image Mode Single-Look Complex
9 x 6 - -
56-100 x 100
Image Mode high-resolution Ellipsoid Geocoded
30 x 30
12.5 x 12.5
56-100 x 100
> 3
Image Mode medium-resolution
150 x 150
75 x 75
56-100 x 100
Image Mode Browse
450 x 450
225 x 225
56-100 x 100
Alternating Polarisation Precision Image
30 x 30
12.5 x 12.5
56-100 x 100
> 1.8
Alternating Polarisation Single-Look Complex
9 x 12
56-100 x 100
Alternating Polarisation Mode high-resolution Ellipsoid Geocoded
30 x 30
12.5 x 12.5
56-100 x 100
> 1.8
Alternating Polarisation Mode medium-resolution
150 x 150
75 x 75
56-100 x 100
Alternating Polarisation Mode Browse
450 x 450
225 x 225
56-100 x 100
Wide Swath Mode medium-resolution
150 x 150
75 x 75
400 x 400
Wide Swath Mode Browse

1800 x 1800


900 x 900
400 x 400
30 to 48
Wave Mode Imagette and Imagette Power Spectrum
9 x 6
5 x 5
Wave Mode Image Spectra
5 x 5
Global Monitoring Mode Image
1000 x 1000
500 x 500
400 x 400
7 - 9
Global Monitoring Mode Browse
2000 X 2000
1000 x 1000
400 x 400
11 - 15

For additional product summary tables refer to "Organisation of Products. 2.2. "

Product Generation

Product generation may fall into two major classes. These are:

  • Systematic - Medium resolution and browse products are generated automatically for all received data in strip-line format.
  • On Request - Products are not generated unless specifically requested by a user, such as Precision, Ellipsoid Geocoded and Single-Look Complex images.

In addition, the systematic products may be subdivided into two categories based on the production time:

  • Near Real Time - There are two types of Near Real Time (NRT) products, those to be produced within 3 hours and those to be produced within one day.
  • Off-line - Some products will be processed off-line. The availability time depends on the complexity of the processing and the availability of auxiliary data. Delivery time ranges from two business days to four weeks. Off-line products benefit from the more precise orbit information which becomes available later.

Stripline Products

Stripline products are generated along a complete segment or an orbit. Geometric and radiometric continuity are ensured along the complete segment or orbit. Scenes can be ordered from within a stripline, then extracted and distributed via the PDS User Services. Scene sized is based on granules, an area consisting of the along-track distance by the full swath width. The framing constraints are that the scene must contain an integer number of granules, beginning and ending anywhere within the stripline and must be a full swath width. Child products may be sized to be any multiple of a granule. Stripline processing of browse, medium- and low-resolution data will produce products for up to 10 minutes data acquisition in Image, Alternating Polarisation and Wide Swath Modes, and up to a full orbit for Global Monitoring Mode.

In order to achieve stripline processing, the full data segment is divided across multiple PF-ASAR processors, as shown in figure2.2 below. The output of each processor is called a slice, and the slices are concatenated together to form the final stripline product. Each slice is divided into an integer number of granules, which are used to facilitate child product extraction.

System design for stripline processing
Figure 2.2 System design for stripline processing

For a detailed description of strip-line processing see the section entitled "ASAR Stripline Product Processing" .

Floating Scene Concept on Archived Products

There is no reason why a user's region of interest should be limited to that which matches the archived product, either in terms of size or geographical position. For these reasons, production has been disassociated from the dissemination and, according to the floating scene concept, a multiple of the minimum scene size only can be disseminated if necessary. The size of a product can be anything from the whole data downlink segment to the minimum scene size, without any constraint on the beginning of the product. Regardless of the size, the extracted product will have a size equal to a multiple of the minimum scene size.

For ASAR, the minimum product size is a single granule, which is a pre-defined, along-track distance by the full swath width.

This flexibility is obtained by the Archiving Facility (ARF), which allows a product to be to selectively extracted from an existing archived product without any processing. This corresponds to the child product concept, which is discussed below. (Also see "Floating scene concept for NRT products" discussed below.)

For products processed systematically, the user selects the position of one or more scenes along the acquired data segment. The scene starts at granule boundary, as shown in figure2.3 below.

The selection of the scene starts at granule boundaryfull size
Figure 2.3 The selection of the scene starts at granule boundary

For products generated on request, such as Alternating Polarisation (AP) and Image Mode (IM) precision products, the user can select a scene starting from any time along the acquisition data segment (no framing constraint), as shown in figure2.4 below. These products have fixed sizes.

The selection of a scene can start from any time along the acquisition data segment
Figure 2.4 The selection of a scene can start from any time along the acquisition data segment

Child Product Concept

A child is the result of the extraction of a set of data from a parent product (Level 0, Level 1B, Level 2). Generation of child products can be formulated in terms of time, Data Set (DS), or Instrument Source Packet (ISP) selection, in terms of either segments or scenes; that is:

  • time window
  • geographic zone (search using the LADS with the help of the PDS inventory)
  • data subset

For generation of scenes, the only extraction criteria available are times. When performing child extraction, it is possible to output either a segment corresponding to the time window, or a set of scenes containing the time window, as depicted in figure2.5 below.

Child Product Extraction
Figure 2.5 Child product extraction

When a child extraction is required against consecutive slices archived at the ARF, the child product generation can apply to several parent products. These parent products are identified through their physical names and their Stripline Continuity Indicators (SCI).

Again, the result of such a child product extraction could be formulated in terms of either segment or scenes.

Child product extraction from consecutive slices
Figure 2.6 Child product extraction from consecutive slices

For a further discussion of these products, as they relate to ASAR, refer to "Child Products" 2.1.1. .

Product generation and extraction
Figure 2.7 Product generation and extraction

Floating scene concept for NRT products

The ARF will be able to generate and distribute scenes associated to the concatenation or the extraction of the different consecutive slices it has received. For NRT mode distribution, the ARF will transmit as quickly as possible each scene to the DF, not waiting for the reception of the set of complete slices before building and transmitting the associated scenes.

Each scene will be transmitted immediately as it becomes complete.

The NRT scene generation is illustrated below:

Scene generation in NRT
Figure 2.8 Scene generation in NRT

General Product Layout

The data production format for one product will consist of:

All data sets are filled with DSRs, and each DSR starts with a time entry. The time entry permits correlation between all data sets at record level and permits subset extraction as will be defined later. The GADS is an exception to this rule.

For a further discussion on each of these components, refer to the section entitled "Definitions and Conventions." 2.3.