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Diffstat (limited to 'www/AIVDM.txt')
| -rw-r--r-- | www/AIVDM.txt | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/www/AIVDM.txt b/www/AIVDM.txt index f86ea86b..9cee13e2 100644 --- a/www/AIVDM.txt +++ b/www/AIVDM.txt @@ -46,15 +46,16 @@ found at <<AIS>>. == Standards == Multiple standards bear on the AIVDM/AIVDO format. This document -exists because assembling them into a complete picture is both -technically difficult and impeded by legal barriers. +exists because assembling them into a complete picture is technically +difficult and was long impeded by legal barriers as well. ITU Recommendation M.1371, "Technical Characteristics for a Universal Shipborne Automatic Identification System Using Time Division Multiple Access" <<ITU1371>>, issued in 2001, first described the bit-level format of AIS radio messages. This standard was proprietary and -expensive. I did not have access to it or any of its followup -revisions while assembling versions of this document up to 1.29. +expensive when issued. I did not have access to it or any of its +followup revisions while assembling versions of this document up to +1.29. ITU-R M.1371 was expanded and clarified by "IALA Technical Clarifications on Recommendation ITU-R M.1371-1" <<IALA>>, which @@ -2195,7 +2196,7 @@ Supersedes an <<IMO236>> message with the same title but FID = 11 and a different binary layout. The exact differences are: (a) The addition of the Position Accuracy field, (b) water level has 12 bits of precision rather than 9 (units of centimeters rather than -decimeters) , and (c) end padding changes from 6 to 10 bits. +decimeters), and (c) end padding changes from 6 to 10 bits. [frame="topbot",options="header"] |============================================================================== |