Data Ingest: FOS Text Feeds

The ingest process component of WXP reads data from National Weather Service (NWS) Family of Services (FOS).  FOS contains several text based data feeds including the Domestic Data Service (DDS), Public Products Service (PPS), Domestic Data Plus (DDP) which is a combination of DDS and PPS and the International Data Service (IDS).  There is one more text-based service that is normally available, which is the FAA 604 data feed. These are all asynchronous data streams running at 9600 or 19200 baud with seven data bits, one stop bit and even parity. All data feeds broadcast several types of meteorological information ranging from standard surface and upper air reports to pilot reports, forecast information, model output statistics and model gridpoint data. Often, an ingest process is started for each type of data feed available at your site.

Domestic Data Plus and International Data Feeds

The Domestic Data feed is a general meteorological data stream providing observed data as well as textual forecast information for North America and surrounding areas. The International feed contains global observed data. The data are arranged into bulletins according to WMO headers that categorize each different type of data reported. A partial list of these WMO headers, their types and description are given in the Appendix (WMO Header Descriptions for Domestic Data Plus Service). The WMO headers can be deduced from the data feed in the following way: a SOH (Start of Header - ASCII character 1) precedes a three digit sequence number. This information is followed by a carriage return, carriage return, line feed [CR][CR][LF] sequence. The next line of data contains the WMO header information, receiving station and time. The format of the header and associated product are as follows:

   [SOH][CR][CR][LF]
   seq[CR][CR][LF]
   header[CR][CR][LF]
   data..........
   [CR][CR][LF][ETX]

Where:

• seq  --  A sequence number which is incremented one for each successive bulletin.
• header --  The WMO header information describing the type, origin and observation time of the data.

The information contained within the bulletin follows this sequence immediately. Individual reports for each station or location are separated by a RS (Report Separator - ASCII character 30) character and the station identifier directly follows the RS character. All lines are terminated with a [CR][CR][LF] character sequence. After the last reported data in the bulletin, an ETX character (End of Text - ASCII character 3) appears.

FAA 604 Data feed

The FAA 604 data feed concentrates on providing data to the aviation community and, as a result, non-aviation information may or may not be provided on a regular basis. Surface, upper air and radar data are reliably broadcast on this feed. The data are arranged into bulletins with a specific FAA bulletin number categorizing each different type of data reported. A partial list of these bulletin numbers, their types and description are given in the Appendix (FAA 604 Bulletin Number Descriptions).

The bulletin number can be deduced from the data feed in the following way: an eight byte sequence which is usually preceded by a SOH (Start of Header - ASCII character 1) and followed by a STX (Start of Text - ASCII character 2). The format of the header and associated product are as follows:

   [SOH]seq00bul[STX]
   data...
   [ETX]

Where:

• seq -- A sequence number which is incremented one for each successive bulletin.
• bul -- The bulletin number describing the type of data.

The actual data within the bulletin follows the STX character. Individual reports for each station or location are separated by a RS (Report Separator - ASCII character 30) character anted by a RS (Report Separator - ASCII character 30) character and the station identifier directly follows the RS character. All lines are terminated with a [CR][CR][LF] character sequence. After the last reported data in the bulletin, a ETX character (End of Text - ASCII character 3) appears.