Recommended Class B AIS transponder

[Storyline]

.....
At least when you miswire NMEA it just doesn't work, unlike the potential for damage and explosions if you decided to wire your negative battery terminal to the domestic positive output of the charger.

Pete

That has proved very useful in the past - I have had to use the trial and error method on occasions !

 

[gianenrico]

I installed a ray 650 bought and brought from the USA; saved 20% on EU prices.
REALLY "Plug&Play", it came with its own GPS antenna, had to by a rubber VHF which stays tucked over one of the saloon shelves.
It is possible to silence it fitting a two way switch (or connecting the two appropriate wires; updating the C70 software DID not bring the possibility to silence it by the chart plotter, unfortunately.
Any way in my understanding, 85% of world's AIS boards are designed and manufactured by the same U.K. Company.

 

[ghostlymoron]

PBO mag did a test fairly recently (Jan 2010 p46-50). I recall that most units were re-badged versions of one manufacturer but can't recall who that was, possibly Comar but suggest you check the article.

 

[Koeketiene]

PBO mag did a test fairly recently (Jan 2010 p46-50). I recall that most units were re-badged versions of one manufacturer but can't recall who that was, possibly Comar but suggest you check the article.

When it comes to electronics/AIS a 3 year old article is hardly 'recent'.
A lot has happened these last years when it comes to Class B AIS.

 

[savageseadog]

I fitted a nearly new Digital Yacht AIT1000 this year for the Fastnet and it worked very well linked up with my Garmin plotter. The tech support on the Digital Yacht site is excellent and there is info on there showing how to use and configure all their units with most other equipment on the market. The guy that runs it must be a genius and can't have a life.

 

[BrianH]

I have a Comar multi. I almost never get the ship's names but always get speed, turn etc. Sometimes the ship's name appears much longer than the 6 minutes it ought to take.
I have a direct USB connection from the Comar, so cannot blame the converter
Irritating

I have been using Open CPN. Which program have you found to be the best in displaying ship names???

I am intrigued by your problem. It is symptomatic of a non-parallel receiver where the alternating channel is out of synchronisation for some time with the target transmitter channels and with only a six minute repetition rate of the static data sentences ... but the Comar is a genuine two-channel parallel receiver, i.e. both channels are simultaneously active.

In fact, it is similar to the problem I experience with my very old, two-channel but non-parallel (single receiver) unit and to replace that I have ordered a modern replacement.

Another problem I have had is that Class B reports never display any static data - not really a problem as Class B vessels rarely constitute a threat so having the ship's name is of no consequence. This is because production of my system in the early 2000s was before the Class B protocol was defined and therefore unprogrammed for in my receiver. The Taiwanese manufacturer never replied to my mails asking if a software upgrade was possible.

Could it be that the missing static data you are experiencing is only from Class B targets? If so you too may need a software upgrade.

Static data is contained in two AIVDM fragment sentences with only the MMSI as common to both, poor signal reception could compound the difficulty of collating all target data - perhaps your AIS antenna (or splitter if used) is not optimal.

I too am using OCPN to display AIS targets and sometimes the static data is incredibly long to appear - up to 15 -20 minutes, but always for Class A appear it does ... eventually. And that is with an old, out-of-date, single-channel receiver, which is responsible for the data delay. Previously I had been using OziExplorer during when the AIS data display was still under development and it was not showing any CPA and TCPA, which is why I switched to OCPN, with which I am reasonably satisfied. Except for the inability to filter out all the Class B spurious alarms I have been plagued with over the last two years.

Whatever, you should contact Comar with your problem, I understand they have excellent support.

Edit:
OCPN has an excellent debug window (Options>Connections>Show NMEA debug window) and you can monitor the AIVDM message flow to check for the Type 5 sentences, using this message description: http://gpsd.berlios.de/AIVDM.html#_type_5_static_and_voyage_related_data

 

[winsbury]

I dropped Actisense a line last week to see if they had any suggestions regarding the missing static data - I cant say a fully understand all these points yet but might be useful for anyone else using a converter to check against:

"Have a look at the NGW-1-AIS conversion list and check the PGNs against those in the Plotter manual. I believe the information you refer to is in PGNs 129040 and 129794.

Can you record an output of the AIS so we can check why this might be happening?

Have you configured the NGW-1 (configuration is with NMEA Reader, link below)?

Ensure that the required PGN’s are enabled in the PGN Tx List. These will be selected by default so shouldn’t need configuring.

Does the NGW have the latest Firmware? It should be version 2.199 – you should be able to see that in the network view of the plotter.

Otherwise from the Firmware tool Actipatch via a PC connection. All software and documents required are here: http://www.actisense.com/products/nmea-2000/ngw1/downloads-ngw1.html"

EDIT:

my HDS plotter does have the latest firmware but noticed this in the release notes: "HDS Gen2 can now transmit and receive
ClassB Static AIS data (with a ClassB AIS device connected) as well as AIS Aids to Navigation"

The detailed descriptions of the PGN's above are detailed here http://www.nmea.org/content/nmea_standards/messages_pgns.asp and both state "An AIS device may generate this parameter group either upon receiving a VHF data link message [n], or upon receipt of an ISO or NMEA request PGN."

So, this seems to imply -
1. the HDS will only word with a class B ais device, not a receive only ais device and
2. depending on how the standard is interpretted, static data might only be sent if the ais unit is polled by the plotter and this is clearly something that a receive only unit cannot do.

I also stumbled on this which shows the limitations of many popular class B devices on this very topic of bad static data http://www.panbo.com/archives/2009/06/nmea_2000_ais_not_yet_right.html

 

[BrianH]

Could someone recommend a Class B AIS transponder please ?

I already have a dedicated VHF antenna and GPS installed on the taffrail so just need the transmitter/receiver.
I would like to have the facility of being able to switch the transmitting part off whilst still receiving AIS info.

Thanks for any thoughts.

I don't wish to make any specific product recommendation but what I can mention is the service I have just received from Milltech Marine, in the Pacific NW of the USA, who specialise in AIS equipment.

As commented earlier in this thread I had ordered a replacement to my ancient, non-parallel, AIS receiver and it was from the above on-line store as I had read good things about them in the way of support and prices, plus they shipped internationally.

My on-line order was immediately acknowledged and a follow-up mail the same day informed me that the package had shipped.

This morning the package was delivered in perfect condition. An hour later I received a promotional mail from Millteck Marine listing a number of items at 10% discount - including the one I had just received. I immediately hit the Reply button to say my package had arrived safely and included a wry comment on the coincident news that it was now 10% cheaper.

There immediately came a response from Doug Miller to say he would refund the difference to my credit card. I had not complained, just made a light-hearted comment as I know there has to be a point when a marketing promotion has to begin and I had timed my purchase before it. No problem.

No connection to Milltech Marine ... but a satisfied customer.