Overview

The NOAAPORT SDI system collects NOAA's real-time environmental data and products transmitted by the four NOAAPORT data channels. These channels are the National Centers for Environmental Prediction (NCEP) and National Weather Service Telecommunications Gateway (NWSTG) data and products, GOES-EAST imagery, GOES-WEST imagery, and Non-GOES Imagery/DCP data. The ingestor is configured for one of these channels before shipping.

The ingestor reformats the NCEP/NWSTG data stream to look like the Family of Services data stream. There are two NCEP/NWSTG output data streams, one for binary data and one for ASCII data. The GOES-EAST and GOES-WEST channels contain satellite data in GINI (GOES Ingest NOAAPORT Interface) format, which are stored on disk.

The ingestor removes various layers of protocol that were used during data transport. First, the HDLC (High-Level Data Link Control) protocol is examined. Flags are located, zero-bit insertions are removed, and the bits in the bytes are reordered from LSB first to MSB first. Then, the other protocol envelopes are stripped away and used to determine which stream the data should be presented on.

The ingestor buffers the data stream, which requires that you only need to keep up with its average rate, not its peak rate. By default, the amount of buffering is set to 50MB, which represents 4.15 minutes of raw data, but you can change it if desired.

Data decoders currently used with Family of Services data require few changes when used with the NOAAPORT Ingestor's data stream. The main difference is that instead of opening an async device, as they may have in the past, they now open a FIFO or a socket. Other differences that occur are not from differences in format, but differences in the data itself. The NOAAPORT data stream contains many more grids and many larger grids than the Family of Services data stream, so you may need to modify assumptions about maximums.

Knowledge of the NOAAPORT system and its data characteristics are not essential for routine operation of an SDI. However, if you experience difficulty, familiarity with these characteristics may help you diagnose operational problems. Refer to http://www.nws.noaa.gov/noaaport/html/noaaport.shtml for NOAAPORT system and data format information.

Knowledge of the SDI files, their structures, or their naming conventions are not considered essential for normal operation of the SDI. However, if you request technical assistance from SSEC, you may be asked to examine these files to assist SSEC in diagnosing your SDI operational problems. Therefore, an overview of these files is provided at the end of this chapter.

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