special arrangements dating service - 421 validating sender

Please note that sample sentences not accompanied by field dumps are not useful; I can get plenty of those.

Field 2 (1 in this example) is the count of fragments in the currently accumulating message.

421 validating sender-55421 validating sender-31421 validating sender-59

If you find this document useful - and especially if it helps you make money - please contribute to maintaining it by supporting the author’s full-time open-source work through [PATREON]. This is a description of how to decode AIVDM/AIVDO sentences.

It collects and integrates information from publicly available sources and is intended to assist developers of open-source software for interpreting these messages.

Some charge subscriptions; others offer time-delayed access for free and charge for a real-time feed.

Still others are pool sites; you join by contributing your feed and receive all feeds.

ITU-R M.1371 revision 4 became available for free download, apparently at some point in early 2011, well after most of this document was assembled.

The ASCII format for AIVDM/AIVDO representations of AIS radio messages seems to have been set by IEC-PAS 61162-100, "Maritime navigation and radiocommunication equipment and systems" [IEC-PAS]. Various public sources indicate that it has been "harmonized" with some version of NMEA 0183, which I also have not looked at because it too is proprietary and expensive, and surrounded by rapacious attack lawyers.

It is open-source friendly, offering a Linux port in source of its software for collecting and forwarding AIS data.

Peter Stoyanov and the other AIS Hub principals have generously donated a live feed to the GPSD project despite the fact that I live 60 miles inland and cannot send them anything interesting.

The detail information on payload formats in this document is mostly derived from these public sources.

Kurt Schwehr is a research scientist at the Center for Coastal and Ocean Mapping at the University of New Hampshire. His work blog at [Schwehr] contains sample messages and descriptions of AIS operation in the wild that shed light on various obscure corners of the specification.

They periodically squawk their position (and course, when applicable), using TDMA (Time Division Multiple Access) technology similar to the way cellphones do to avoid mutual interference.

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