C++ decoder for Automatic Identification System for tracking ships and decoding maritime information
C++ Python Makefile M4 Other
Latest commit e35a5ba Sep 26, 2016 @schwehr Cleanup nmea_messages.py.
- Decode -> DecodeLine
- Document nmea_messages
- msg -> message for clarity
- Add "Handle" to functions that handle indivitual NMEA messages.
  Allows introspection to find the handlers from __dict__.
- Fix TXT message handling
- Add many TODOs
- Initialize HANDLERS in one place at the end.
  Count on tests to catch missing entries.




Library for decoding maritime Automatic Identification System messages.

See Also

Automatic Identification System

Other open source AIS projects:


Building with Python

$ python setup.py build
$ python setup.py install

Testing with Python

$ virtualenv ve
$ source ve/bin/activate
$ python setup.py test

Building with CMake

$ cmake .
$ make

Building with legacy Makefile

$ make -f Makefile-custom test


There are two interfaces to libais, one high-level iterator based one and a low-level fast C++ only one. The iterator based interface is accessed the following way:

import ais.stream
with open("file.nmea") as f:
    for msg in ais.stream.decode(f):
        print msg

To use the low-level C++ interface directly, you need to handle multi-line messages and padding yourself:

import ais
ais.decode('15PIIv7P00D5i9HNn2Q3G?wB0t0I', 0)
ais.decode('402u=TiuaA000r5UJ`H4`?7000S:', 0)
ais.decode('55NBjP01mtGIL@CW;SM<D60P5Ld000000000000P0`<3557l0<50@kk@K5h@00000000000', 0)

There is also support for converting parsed messages to the structure output by GPSD / gpsdecode. For full compatibility, you have to write the resulting message dictionaries to a file with json.dump() and add a newline after each message.

import ais.stream
import json
import ais.compatibility.gpsd

with open("infile.nmea") as inf:
    with open("outfile.gpsd") as outf:
        for msg in ais.stream.decode(f):
            gpsdmsg = ais.compatibility.gpsd.mangle(msg)
            json.dump(gpsdmsg, outf)

AIS Specification Documents

  • ITU-1371, ITU-1371-{1,2,3,4]
  • e-Navigation
  • IMO Circ 236
  • IMO Circ 289
  • EU RIS


The C++ code was switched to the Google style in November, 2012. Indenting should be by 2 spaces.


$ git clone https://github.com/schwehr/libais
$ cd libais
$ virtualenv ve
$ source ve/bin/activate
$ pip install -e .[tests]
$ python setup.py test
$ py.test --cov=ais --cov-report term-missing


$ git clone https://github.com/schwehr/libais
$ cd libais
$ virtualenv ve
$ source ve/bin/activate
$ pip install -e .[test]
$ python setup.py develop
$ python setup.py test
$ py.test --cov=ais --cov-report term-missing