diff options
| author | Eric S. Raymond <esr@thyrsus.com> | 2010-03-11 02:04:06 +0000 |
|---|---|---|
| committer | Eric S. Raymond <esr@thyrsus.com> | 2010-03-11 02:04:06 +0000 |
| commit | f43c8f8f726750fc90b0d45e72175986ae567c86 (patch) | |
| tree | 62a12259f132fb8edea9c22033e026a6b4df83fe /www | |
| parent | 7f4cc15a3fef820705b606489ebc73223ea4237a (diff) | |
| download | gpsd-f43c8f8f726750fc90b0d45e72175986ae567c86.tar.gz | |
Notes on unobserved variants.
Diffstat (limited to 'www')
| -rw-r--r-- | www/AIVDM.txt | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/www/AIVDM.txt b/www/AIVDM.txt index 20097edb..0580053d 100644 --- a/www/AIVDM.txt +++ b/www/AIVDM.txt @@ -1069,6 +1069,10 @@ frequency with which the subordinate station should report per is specified at the level of TDMA slot numbers; see <<IALA>> for the detailed specification. +Note: While the 96-bit form of Type 16 is not uncommon, the 144-bit +form is extremely rare. As of March 2010 it has not been observed even +in long-duration samples from AISHub. + === Type 17: GNSS Broadcast Binary Message === Message type 17 is used to broadcast differential corrections for GPS. @@ -1556,6 +1560,9 @@ interpreted. Otherwise that field span becomes part of the message payload. The data fields is not, in contrast to message type 26, followed by a radio status block. +Note: Type 25 is extremely rare. As of March 2010 it has not been +observed even in long-duration samples from AISHub. + === Type 26: Binary Message, Multiple Slot === Takes up 60-1064 bits (up to 5 slots). @@ -1581,6 +1588,9 @@ is 224 and adds the note "Allows for 32 bits of bit-stuffing." The 20 radio status bits are always present after end-of-data in the last slot and are in the format specified by <<IALA>>. +Note: Type 26 is extremely rare. As of March 2010 it has not been +observed even in long-duration samples from AISHub. + == Local extensions == Some regional authorities extend the AIS message set. |