Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 19-09-2013, 09:37   #1
Registered User

Join Date: Jan 2011
Location: London
Boat: Oyster 49
Posts: 46
No vessel name on AIS but everything else

I am running OpenCPN I have windows XP PC AIS comes from Comar multi which includes VHF splitter and goes direct to the USB

I was under the impression that lots of boats were not showing their boat name but recently realised that this is not the case. Every other information seems OK, MMSI, GPS position, rate of turn

The Comar is a dual channel receiver Comar Systems AIS-Multi

Sometimes the boat name is shown but rarely.

IS there something that I should do to make the boat name always appear??

Thanks

Tudorsailor
__________________

__________________
Tudorsailor is offline   Reply With Quote
Old 19-09-2013, 10:18   #2
bcn
Registered User

Join Date: May 2011
Location: underway whenever possible
Boat: Rangeboat 39
Posts: 2,759
Re: No vessel name on AIS but everything else

AIS distinguishes between static and dynamic data.

The second ones are updated more frequently and include the data you are mentioning.
Static data may need several minutes to show up and include items like the ship's name, dimensions or in the case of AIS Class A units destination and ETA.
You can see very easily if static data are available: the color of the icon turns to green from yellow.
For further information I would suggets to consult O's online manual (the "?" button).

If the static data does not turn up with a bit of patience you might check the antenna as well: if you have a poor reception, the static data are more probable to be "overseen" by the Comar.
__________________

__________________
bcn is online now   Reply With Quote
Old 19-09-2013, 10:29   #3
Registered User
 
s/v Moondancer's Avatar

Join Date: Nov 2008
Location: Fiji but heading for Alaska
Boat: Tayana 55
Posts: 1,225
Re: No vessel name on AIS but everything else

We run a different system but we find a significant distance difference in the two types of data, we get the basics at 20-25 miles but need to be closer, about 12-15 miles to get the name.

We use a splitter but the antenna is 76 ft above the water so we get exceptional reception.
__________________
Phil

"Remember, experience only means that you screw-up less often."
s/v Moondancer is offline   Reply With Quote
Old 19-09-2013, 10:35   #4
Registered User
 
Bregts's Avatar

Join Date: Oct 2010
Location: Vuda, Fiji
Boat: Vd Stadt 34
Posts: 80
Re: No vessel name on AIS but everything else

I had the same problem for a time. Only the dynamic data showed up. Resulting in having to call ships on vhf by there location or mssi. Turned out the ais antenna plug was not inserted in the ais transponder all the way. Once I fixed this I could see the static data of almost all vessels.
__________________
Bregts is offline   Reply With Quote
Old 19-09-2013, 10:51   #5
bcn
Registered User

Join Date: May 2011
Location: underway whenever possible
Boat: Rangeboat 39
Posts: 2,759
Re: No vessel name on AIS but everything else

Quote:
Originally Posted by s/v Moondancer View Post
We run a different system but we find a significant distance difference in the two types of data, we get the basics at 20-25 miles but need to be closer, about 12-15 miles to get the name.

We use a splitter but the antenna is 76 ft above the water so we get exceptional reception.
Phil, this is logical:

the dynamic data are sent (Class A) depending on SOG of the vessel every 6 or 10 sec (or even more often when turning) while static data are sent every 6 minutes. Even if you miss 80% of the dynamic messages you will have the target identified and can track it (would be a report update every 30 or 60s), while missing the same number of packets in the case of static data would imply 30 minutes.

For class B the dynamic updates are
Class B “SO” shipborne mobile equipment not moving faster than 2 knots 3 mins
Class B “SO” shipborne mobile equipment moving 2-14 knots 30 secs
Class B “SO” shipborne mobile equipment moving 14-23 knots 15 secs
__________________
bcn is online now   Reply With Quote
Old 19-09-2013, 10:55   #6
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,867
Images: 4
Re: No vessel name on AIS but everything else

Quote:
Originally Posted by bcn View Post
Static data may need several minutes to show up and include items like the ship's name, dimensions or in the case of AIS Class A units destination and ETA.
A vessel sends its static data is once every six minutes. If you are using a single-channel receiver (not the case with the OP) you will only get half of those transmissions. If the signal is weak or there is interference, some percentage of the transmissions will be garbled and discarded.

So, it can take a while for the static data to appear, and if you have poor connections, cable, etc, it can take a long time.
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is online now   Reply With Quote
Old 19-09-2013, 23:50   #7
Registered User

Join Date: Jan 2011
Location: London
Boat: Oyster 49
Posts: 46
Re: No vessel name on AIS but everything else

Quote:
Originally Posted by bcn View Post
Phil, this is logical:

the dynamic data are sent (Class A) depending on SOG of the vessel every 6 or 10 sec (or even more often when turning) while static data are sent every 6 minutes. Even if you miss 80% of the dynamic messages you will have the target identified and can track it (would be a report update every 30 or 60s), while missing the same number of packets in the case of static data would imply 30 minutes.

For class B the dynamic updates are
Class B “SO” shipborne mobile equipment not moving faster than 2 knots 3 mins
Class B “SO” shipborne mobile equipment moving 2-14 knots 30 secs
Class B “SO” shipborne mobile equipment moving 14-23 knots 15 secs

Can you tell me the ideal settings on the PC especially the baud rate?
thanks
ts
__________________
Tudorsailor is offline   Reply With Quote
Old 20-09-2013, 00:04   #8
bcn
Registered User

Join Date: May 2011
Location: underway whenever possible
Boat: Rangeboat 39
Posts: 2,759
Re: No vessel name on AIS but everything else

Quote:
Originally Posted by Tudorsailor View Post
Can you tell me the ideal settings on the PC especially the baud rate?
thanks
ts
Should be 38400
__________________
bcn is online now   Reply With Quote
Old 20-09-2013, 01:46   #9
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,867
Images: 4
Re: No vessel name on AIS but everything else

Quote:
Originally Posted by Tudorsailor View Post
Can you tell me the ideal settings on the PC especially the baud rate?
thanks
ts
As bcn said, for AIS the bit rate is 38400 bps. The other settings are eight data bits, no parity, but I would be quite surprised to see an AIS-aware program get these wrong.

And, if the serial port is set incorrectly you will get no data through whatsoever. When it comes to these settings there's no such thing as "almost right". They're either correct or incorrect.
__________________

__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is online now   Reply With Quote
Reply

Tags
ais

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 10:31.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.