Chapter 2
ASAR Products and Algorithms

In general, the ENVISAT product strategy is to offer a simple, flexible product format and structure, featuring a unique format, as well as stripline processing and a floating scene concept. ENVISAT product data sets will extend over a five-year period, and will include data from a number of instruments and operating modes collected in continuous operation or discrete segments. In order to handle this volume and range of data, it is necessary to separate the data into manageable sizes and deliver them as product files. The product strategy is based on:

• a systematic processing of all acquired data into medium resolution of stripline products in order to have a reference archive with no discontinuities between pixels along-track
• child products extracted from parent products at Level 0, Level 1B or Level 2
• a floating scene concept to allow flexibility for users to order a portion of the stripline the product that fulfils their needs.
• processing of precision, high resolution products on request

Furthermore, as a design rule, the number of facilities generating and using product information has been minimised to limit the effect of any changes in the contents of the product header in the application software.

The general layout for all ENVISAT includes the following records:

• Main Product Header (MPH) - The MPH has a fixed length and the format is identical for all ENVISAT products.
  

• Specific Product Header (SPH) - The SPH is defined for each product and provides additional information, applicable to the whole product, related to the processing.

• Data Set (DS) - The DS contains the instrument's scientific measurements. Product Confidence Data (PCDs) - The PCD provides an evaluation of the overall quality of the product.

This chapter of the ASAR Handbook will provide detail on all of the ASAR products and associated algorithms, including a discussion on ASAR characterisation and calibration, as well as hints on data handling. The details of the layouts for each product will be found in chapter "Data Formats."(Chapter 6. )