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-   -   What’s Going on with this AIS Target? (https://www.cruisersforum.com/forums/f13/what-s-going-on-with-this-ais-target-219646.html)

DefinitelyMe 16-06-2019 13:22

What’s Going on with this AIS Target?
 
1 Attachment(s)
Notice the ‘heading’ field. Anyone know what’s going on here?

Attachment 194023

Emmalina 16-06-2019 13:56

Re: What’s Going on with this AIS Target?
 
Its going to another dimension LOL

StuM 16-06-2019 16:22

Re: What’s Going on with this AIS Target?
 
Maybe an artifact of the lack of boat dimensions?

Paul L 16-06-2019 17:45

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by DefinitelyMe (Post 2909838)
Notice the ‘heading’ field. Anyone know what’s going on here?

Attachment 194023

Is the Lat and Long correct?

smac999 16-06-2019 18:45

Re: What’s Going on with this AIS Target?
 
Class b doesn’t transmit heading. So something is weird. Maybe on your end.

DefinitelyMe 16-06-2019 20:16

What’s Going on with this AIS Target?
 
Quote:

Originally Posted by smac999 (Post 2910034)
Class b doesn’t transmit heading. So something is weird. Maybe on your end.



Yea possibly. I’m not too bothered, I just thought it was kind of cool. Even though it was only 2.5 miles away and visibility was great I couldn’t see it, so it’s presumably some kind of beacon.......... but then it’s also moving at 10 knots?! Who knows. There’s a lot of weird-looking stuff out there.

I was chatting to one of the conservation officers on St. Helena a couple of months ago. They told us about a long-liner that they were tracking on radar whose course was really erratic. They tracked it for a while and an image emerged - the coast of China. They’d set their AIS to be offset by x thousand miles and then fished illegally in the middle of the South Atlantic......... appearing according to AIS to be just off the coast of China.

We saw similar stuff in Indonesia; you get a target on AIS and the CPA is 8,000 miles.

Paul L 16-06-2019 20:22

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by smac999 (Post 2910034)
Class b doesn’t transmit heading. So something is weird. Maybe on your end.

Class B messages include heading.
https://www.navcen.uscg.gov/?pageName=AISMessagesB

IslandHopper 16-06-2019 20:51

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by smac999 (Post 2910034)
Class b doesn’t transmit heading. So something is weird. Maybe on your end.

Quote:

Originally Posted by Paul L (Post 2910077)
Class B messages include heading.
https://www.navcen.uscg.gov/?pageName=AISMessagesB

The correct statement should read "most Class B don't transmit HDG".....

Although the data output format supports heading information in "some" Class B units, in general units are not interfaced to a compass so this data is seldom transmitted.....

If a vessel is required to carry a Class A then it is required to be interfaced with a compass feed, there is no such requirement for Class B.....

Without a compass interface the Class B cannot transmit a Heading, True or otherwise.....

Paul L 17-06-2019 00:49

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by IslandHopper (Post 2910088)
The correct statement should read "most Class B don't transmit HDG".....

Although the data output format supports heading information in "some" Class B units, in general units are not interfaced to a compass so this data is seldom transmitted.....

If a vessel is required to carry a Class A then it is required to be interfaced with a compass feed, there is no such requirement for Class B.....

Without a compass interface the Class B cannot transmit a Heading, True or otherwise.....

That's probably true with older installs. With more boats using nmea 2000 buses it should be less so. My older Emtrak AIS support 2000. So heading comes from the Autopilot compass that is on the bus.

IslandHopper 17-06-2019 01:11

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by Paul L (Post 2910158)
That's probably true with older installs. With more boats using nmea 2000 buses it should be less so. My older Emtrak AIS support 2000. So heading comes from the Autopilot compass that is on the bus.

I wasn't referring to either old or new, NMEA O183 or 2000, i was referring to the owners not interfacing a compass, the vast majority still don't no matter the capability of there particular unit......

Paul L 17-06-2019 01:29

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by IslandHopper (Post 2910163)
I wasn't referring to either old or new, NMEA O183 or 2000, i was referring to the owners not interfacing a compass, the vast majority still don't no matter the capability of there particular unit......

Understood, my point was if you plug into the 2k bus then heading just comes along with it without doing any interfacing, assuming you have a compass on the bus for an AP

IslandHopper 17-06-2019 01:32

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by Paul L (Post 2910167)
Understood, my point was if you plug into the 2k bus then heading just comes along with it without doing any interfacing, assuming you have a compass on the bus for an AP

:thumb:

GILow 17-06-2019 02:46

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by DefinitelyMe (Post 2909838)
Notice the ‘heading’ field. Anyone know what’s going on here?

Attachment 194023



Weird stuff like this aside, are you happy with your Matsutec AIS? I’ve fitted one but have had no chance to test it yet.

DefinitelyMe 17-06-2019 04:30

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by GILow (Post 2910184)
Weird stuff like this aside, are you happy with your Matsutec AIS? I’ve fitted one but have had no chance to test it yet.



Yes, very. For the price, functionality, and convenience of being able to program your own MMSI into it it’s great. We only bought ours to satisfy an Indonesian requirement that ‘all foreign vessels must be equipped with an AIS transponder’ but we’ve come to really love it. Only downside is that the CPA alarm doesn’t work. Not a problem for us because we have a separate receiver on which it does work, but if yours is the same and it’s the only AIS you have it could be a major disappointment. I’d read some reviews before I bought it which said similar things. Fingers crossed yours works OK.

GILow 17-06-2019 05:12

Re: What’s Going on with this AIS Target?
 
Quote:

Originally Posted by DefinitelyMe (Post 2910212)
Only downside is that the CPA alarm doesn’t work. Not a problem for us because we have a separate receiver on which it does work, but if yours is the same and it’s the only AIS you have it could be a major disappointment. I’d read some reviews before I bought it which said similar things. Fingers crossed yours works OK.

That's a worry. I had not read of that particular problem....

I think my CPA alarm is working from my testing in the marina, but I will find out more. Thank you for the heads up.


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