Chapter 1

SDI Overview

The SSEC Data Ingestor (a.k.a. SDI-104 or SDI) is based on a PC/104-Plus SSEC Ingestor Board on a PC running DSL (an embedded Linux distribution). It takes a simple approach to satellite data ingesting by receiving the clock and data from a bit sync and writing the raw bits to disk with minimal processing. There is no scheduling required as all data are saved.

For high data rate satellites, such as GVAR and POES, the entire serial data stream is ingested into memory, blocked into 1 Mbyte files, and written to disk. These files are called Stretched Data Format (SDF) files. An independent program analyzes the SDF files to build index files to the information in the SDFs. Data access is handled by an ADDE server running on the ingest processor without interfering with the ingest process.

The advantages to these approaches are:

For the high data rate approach, SDF files usually use less disk space than McIDAS Area files; therefore, more data can be stored on-line.
The SDI runs without operator intervention. After attaching the clock and data cables and powering up the box, data ingestion begins.
The same hardware works for multiple satellite families; i.e., the same hardware that handles GVAR also handles POES, Meteosat, etc. Only the software varies.

This chapter is divided into the following sections:

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