Error on AIS messages

[audiether]

My NMEA stream contains AIS messages in the following format:

!AIVDM,1,1,,A,ENkb9ONaR@@@@@@@@@@@@@@@@@@;kaD09EE>`00003vP000,4*2C

When I try to parse this message I get a ParseError.

Any way to enable parsing AIS messages?

[Knio]

Hi, unfortunately we don't have support for AIS messages. If you are able to help contribute code, or even just provide references and samples, it would be appreciated!

[audiether]

I doubt I'll be able to contribute much in the way of code... I'm much more of a hack than an experienced programmer. :-)

I can definitely provide some sample messages and see what else I can find in the way of resources. I'm on the road and need to be on the boat to get the samples, so it will be about two weeks, but I will definitely post here.

THANK YOU for pynmea2!!!

[audiether]

Here are the details on the data structure:
http://catb.org/gpsd/AIVDM.html

[klint-k]

try this github

https://github.com/schwehr/libais

[rtprio]

@Knio how would one structure the fact that ais messages can be more than one line? Keep track of the count and re-parse? I'm not sure one can assume the next line would be the next part of the message, but I haven't seen any examples otherwise.

>>> foo = pynmea2.parse("!AIVDM,2,1,6,B,56:fS:D0000000000008v0<QD4r0`T4v3400000t0`D147?ps1P00000,0*3")
>>> foo.is_complete
False
>>> foo.parse("!AIVDM,2,2,6,B,000000000000008,2*29")
>>> foo.is_complete
True

That's just getting the whole binary blob; I'm not exactly sure how to make it magically re-split when it comes time to .render() it again. It seems there are assumptions than the output is a single line again.

[xOneca]

(Disclaimer: I have zero knowledge of AIS, but maybe I don't get too far)

I would let pynmea take care of the "transport" of the binary data in chunks, as it arrives. Then I would have an "upper stage" to which feed those blobs, and let it join and interpret the data as a whole.

For rendering, I would split the binary data in chunks and then encode each chunk in its own message. But this, again, using a first stage to split, and then pynmea (if it can) to encode them.