How to Decode Argos

Web Site Retrieved SeaTag Data

Argos transmitted SeaTag data should normally be automatically retrieved from CLS's server using the SeaWatch utility. SeaWatch replaced the older data retrieval method for SeaTag, in which files raw Argos logs were manually retrieved from the Argos web site at www.argos-system.org as .csv files.

Decoding of such Argos web site retrieved files is done with the SeaDock utility. Since Argos data is only available on-line for the last 20 days, SeaDock may be used to decode data previously retrieved from the web site or from CLS archives, but no longer available on-line for retrieval via SeaWatch. The method currently only supports files from SeaTag-MOD devices and SeaTag-GEO devices up to firmware version V2.xx. Other SeaTag data can only be decoded by SeaWatch.

Inspecting Argos web site retrieved logs

Argos web site retrieved .csv logs can show some inconsistencies that must be manually corrected before a log can be converted. Open the .csv log in Excel and inspect for the following per the screen dump.

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The Argos .csv file list messages received by the Argos constellation one message per row. Each message consists of meta data field (orange), and anywhere from 3 to 31 data bytes transmitted by the tag (green). The first row of the log contains the column header (yellow). The number and type of meta data fields can vary. Thus, SeaDock uses the column header to identify the SeaTag data fields. The header naming and its alignment with the packet data must be precise, or else the conversion process will fail. Watch for the following:

  1. The column headers for the data bytes must be SENSOR #01 for the first byte, SENSOR #02 for the second byte and soon up to SENSOR #31 for the 31st byte as available (full-length packets are 31 bytes for SeaTag-MOD and 19 bytes for SeaTag-GEO).

  2. The first data byte (first green column) must be aligned with the SENSOR #01 header. If not properly aligned, adjust the header so that SENSOR #01 coincides with the first data byte. Check all rows for proper alignment with the header. Inconsistencies sometimes appear. Data bytes can be recognized by having values from 0 to 255 if stated decimal, or 00 to FF if stated hexadecimal.

  3. Check if the message bytes are stated in decimal (0-255) or hexadecimal (00-FF). You will subsequently select either format in the conversion process.

Once you have inspected and corrected a log file in Excel, save it as a .CSV file. Depending on your computer's regional settings, .CSV will be either comma or semicolon delimited. Either one will work with SeaDock, as long as the .CSV file appeared correctly in Excel. If you did edits of the .csv file in another program such as Notepad, compliance cannot be guaranteed. For example, editing a file may result in a comma being used as both the field delimiter and the 'decimal comma' in the European system. This will confuse SeaDock.

Converting an inspected log

After having saved the corrected log as a .csv file, convert:

  1. Select File→ Load Argos Log… in SeaDock.

  2. Select the .csv file as your source file. SeaDock will automatically propose a name for the converted destination file, adding _processed to the source file name.

  3. Make sure Decimal or Hexadecimal data format is set corresponding to your inspection of the log.

  4. Click the Process Log button.

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Viewing and Sorting the Decoded Log

The screen dump below shows portions of a decoded log. The headers of all supported data packets types, each corresponding to one received message, are at the top (yellow). Below that are the alternating raw (SDPT_ARGOS) and corresponding decoded packets (green). The first byte in each message specifies the packet type. If a packet type was not recognized, i.e. did not correspond to one of the packets supported by this version of SeaDock (yellow), then the data bytes of the message are simply listed as numbers (red).

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