Signal K Implementation

[Hakan]

Bram..
"Satellites status" i.e. $GPGSV is not parsed by SignalK.

[Hakan]

All..
Anyone having N2k knowledge about AIS messaging?
A question about the blue sign message in N2k format?

https://github.com/SignalK/signalk-p...ment-590527340

[stevead]

Wouldn't it just be the manoeuvre indicator field of PGN 129038 ?

[Hakan]

Yes, that must be the one for the blue sign ON/OFF but there's also a need for the Inland Indicator to tell that now this field is used for the blue sign and not maneuver. The blue is bit 51->6 and the "Inland" at 41->10 in message 8, NMEA0183

[stevead]

As per the standard, wouldn't the definition of an inland vessel simply require the IMO number to be set to zero ?

In OpenCPN you determine whether a ship is operating in Inland European Waters by looking for Message Type 8 with the appropriate DAC value.

The same fields are available in the relevant NMEA 2000 AIS messages,

[Hakan]

"The same fields are available in the relevant NMEA 2000 AIS messages,"
Yes I suppose so. Do you've a clue how it's named? I'm not at all N2k experienced but understand it's not obvious to find that info? It's also discussed in SK nmea0183 parser issues.
Many thanks for your help.
Håkan

[stevead]

Message Type 5 (Class A Static & Voyage Related Data) is sent as PGN 129794 and Message Type 8 is sent as PGN 129797

In the TwoCan (and experimental Actisense) plugins while I do parse most of the AIS related PGN's, I do not parse PGN 129797 as I have yet to see any sample NMEA 2000 data and therefore cannot deduce how the values are laid out in the variable length binary message field.

For example how many bits/bytes are used to encode the Designated Area Code, Functional ID etc. We all know how to encode/decode these in a NMEA 183 VDM sentence, but without sample data, I personally have no idea how to extract them from the NMEA 2000 message.

Do you have any sample PGN 129797 messages ?

[Hakan]

A few samples in attached file. (Take away .pdf)

[stevead]

What you attached are NMEA 183 sentences. NMEA 2000 messages are binary.

You need to get a NMEA 2000 network capture from an AIS transmission operating in EU Inland Waterway's mode.

From my perspective I can read any of the formats supported by my TwoCan Plugin (candump, Yacht Devices, Canboat and TwoCan Raw) and by my experimental Actisense plugin (Actisense EBL log format).

[Hakan]

Yes of course it was. Sorry for the misunderstandings.
But I think enough info is now collected to finalize the SignalK and OCPN part of this Q. (Blue sign)
What I also newly learned is that a official ship IMO/SOLAS seems to not be able to use AIS according to IEC 61162-3 (N2K) but shall use IEC 61162-1 or 61162-2 = NMEA0183 for a AIS system connection.




Thanks

[bcn]

IEC61162-3 deals with the integration of N2K into networks on SOLAS vessels.
N2K however is only a standard of NMEA, not a IEC one.
Another point interesting to see: latest update of 61162-3 is from 2008...


IEC61162-450 covers "lightweight Ethernet" for more complex networks on vessels. Call it 61162-1 (=NMEA0183) via Ethernet.
Carries AIS of course.


We can see a very clear distinction between N2K as technology for leisure crafts and IEC61162-1, -2 and -450 (-460) for the others.

[Shipraiser]

Originally Posted by Hakan

What I also newly learned is that a official ship IMO/SOLAS seems to not be able to use AIS according to IEC 61162-3 (N2K) but shall use IEC 61162-1 or 61162-2 = NMEA0183 for a AIS system connection.

A bit confusing with half the discussion here and half on Github so I'll post my entry here as well;

IMO "GUIDELINES FOR THE INSTALLATION OF A SHIPBORNE AUTOMATIC IDENTIFICATION SYSTEM (AIS) " says

3.3 Display system
If there is navigational equipment capable of processing and displaying AIS information such as ECDIS, radar or an integrated system available on board the ship, the AIS Class A mobile system may be connected to that system via the AIS Presentation Interface (PI). The PI (input/output) should meet the requirements of IEC 61162-2.

and

4.1 External Sensors
The AIS has interfaces (configurable as IEC 61162-1 or 61162-2) for position, heading and rate of turn (ROT) sensors.

IEC 61162-1 is NMEA0183 and 61162-2 is NMEA0183-HS (38400bps)

N2K is IEC 61162-3

https://www.e-navigation.nl/sites/de...SN_Circ227.pdf
https://en.wikipedia.org/wiki/IEC_61162

BTW, Solas equipment is now going straight to Ethernet using IEC 61162-460:2015(E) standard.

NMEA has proposed PGNs over Ethernet, called OneNet for leisure crafts....
https://www.nmea.org/content/STANDARDS/OneNet

/Marcus

[bcn]

Originally Posted by Shipraiser

A

N2K is IEC 61162-3

/Marcus

Marcus..



just to some degree.
If you fetch the public available preface of the -3 standard
https://webstore.iec.ch/preview/info...ed1.0%7Den.pdf
you will see something I would call a "polite approach to say No". From 2008.

Electrical and interface descriptions but without entering into the PGNs for example. Not included in the -3 text.

This part of IEC 61162 has been developed by the IEC technical committee 80 working group 6, to meet the requirement for a versatile and economic means of connecting a wide range of marine navigation and radiocommunications equipment aboard SOLAS vessels. The National Marine Electronics Association’s Standard Committee has developed the NMEA 2000®1 standard. The NMEA2 2000 Standard provides for capabilities across all classes of vessels.


The development of NMEA 2000 began in 1994 and was completed in 1999. More than a dozen manufacturers worldwide conducted a two-year beta test. The finalised NMEA 2000 standard version 1.000 was published in 2001. IEC and NMEA have worked together since 1999 to ensure that the NMEA 2000 standard fully supports SOLAS applications. NMEA 2000 version 1.200 was published in 2004, with expanded support for redundant messaging and for equipments such as AIS.


The need for an improved standard, compared with IEC 61162-1 and IEC 61162-2, has arisen due to the increased complexity of the latest equipment and systems. This requires multiple links between equipment and greatly improved communication speed. The parts 400 of the IEC 61162 series have already been issued and cater for the most complex systems to be found on board a ship.


This new part 3 of IEC 61162 adopts the controller area network (CAN) technology, already well established for many industrial systems. This permits a versatile system to be established with the minimum of effort and reasonable cost. The equipment types supported and the sentence data content developed for IEC 61162-1 has been retained.


IEC 61162-3 describes a low cost, moderate capacity, bi-directional multi-transmitter/multi-receiver instrument network to interconnect marine electronic equipment.
The connectors and cables used are compatible with industrial bus systems for instance DeviceNetTM3 and ProfibusTM4.


IEC 61162-3 provides for the application of NMEA 2000 aboard SOLAS vessels. Exceptions, additions and specific requirements for implementation upon SOLAS vessels are contained in this document.

OneNet - N2K over Ethernet - has been proposed by NMEA since quite some years. Products and applications yet to be seen.

[Hakan]

Originally Posted by stevead

Message Type 5 (Class A Static & Voyage Related Data) is sent as PGN 129794 and Message Type 8 is sent as PGN 129797

Do you have any sample PGN 129797 messages ?

stevead..
Talking about PGN through SK for message 8 I think it's covered by the SK team and the decoder they use. So whatever comes from a N2K connected AIS for the blue sign it will be covered.
The other part is the indication of being an EU Inland vessel. It's in message 1,2 or 3. That part is obviously not so clear when talking PGN. And to catch an Inland vessel using a N2K connected AIS will not be straight forward I assume. For that part of the SK we have to see what the future can give.

The NMEA0183 AIS part of SK parsing would now, thanks to the SK team, be clear. Again when talking EU Inland blue sign as was the origin of this nice discussion.

Let's see when this SK feature is released and OCPN is adapted to that.
Thanks all.
Håkan

[teppokurki]

N2K sample data with AIS: https://github.com/SignalK/signalk-s.../aava-n2k.data