Disappearing AIS targets

[[email protected]]

Last year we replaced much of our electronics. New instruments include Es95 MFD, Ray60 VHF, Raymarine Digital Radar. This is interfaced to our existing SmartPilot S2, and AIS 250. We also have a new VHF antennae.

The antennae is run to the AIS and then connects from the AIS to the VHF. Radio functionality is fine.

In another thread I reported that the MFD would lose the name and other information on targets while a different navigation program (OpenCPN) would not. It was determined that the OpenCPN has a cache of mmsi/names file, whereas the Es does not. Feature request was made.

This is a different problem.

I have come to realize that targets are DISAPPEARING from the Es95 but not the OpenCPN program. Last week I was sailing across SF Bay and AGAIN had a target DISAPPEAR from the display, while it did continue to display on the OpenCPN software being fed the same data. This was a large ship leaving from east of us and heading west out the Golden Gate Bridge.Their course was across our path and I was paying attention to the vector I set on the MFD. Then it disappeared. We have had situations where fog sweeps into SF Bay -- it happens. Having a target disappear in the fog would be many times worse than disappearing in good daylight conditions. Both are bad.

Configuration . . . the antennae is at the top of the mast and a cable goes to the base of the mast where it connects to a cable that was already in place in the previous system. That goes to the AIS 250, and a short cable connects from the AIS to the Ray 60. I have two pairs connected to the AIS 250 Nema Out. One to the Raymarine system and another to a "MiniPlex Lite" and then a COM/USB connection to a computer.

It's difficult to document a disappearing target because I can't memorize all targets on display and one then missing, let alone do a screen shot before it disappears. None-the-less, attached are two screenshots from the MFD. The area is the entrance to San Francisco Bay. In Dump006 at 21:36 there is no AIS target in the entrance to SF Bay, but in Dump007 at 21:38 there is . . . two minutes later! My recollection is that I had seen this AIS target before it disappeared. In any case we regularly view AIS targets out in the shipping lanes (and do look for them as they can be on us sooner than one might think). I'm hard pressed to think the second screen shot was the first we had seen of this ship.

I'm finding that the AIS has become more of a troubleshooting problem than a help in navigation. I need find out what's going on soonest.

Robert

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Robert,

Onboard your vessel, is it normal for the AIS250 to be interfaced to both your PC and to the MFD's NMEA 0183 input port? If so, and it has been interfaced as specified within your thread, then please note that paralleling the 38400 BAUD output of the AIS250 may indeed be responsible for the NMEA 0183 signal supplied to the MFD dropping below that which the MFD can support. With regard to the AIS250 and AIS500 products, Raymarine has historically recommended that the 38400 BAUD NMEA 0183 output from these products not be paralleled. In the case of the AIS500, it was further stated that simultaneous use of the product's 38400 BAUD NMEA 0183 output leads and its DB-9 Serial Plug were prohibited. Accordingly, it is recommended that the AIS250 be disconnected from the "MiniPlex Lite" and that the AIS250's 38400 BAUD output port only be interfaced to the MFD's NMEA 0183 input port alone.

Alternatively should AIS data from the equipment specified additionally need to be interface to a PC, then it would typically be recommended that the AIS250 instead be interfaced to a powered and properly terminated SeaTalkng / NMEA 2000 backbone to which the a/c/e/eS/gS-Series MFD had also been interfaced. A NMEA 0183 to NMEA 2000 data bridging device supporting AIS sentences (ex. Actisense NGW-1-ISO-AIS) would be used for such purposes. Any other NMEA 0183 devices would similarly be interfaced to the SeaTalkng / NMEA 2000 backbone. The PC would then be interfaced to the system via a NMEA 2000 to USB gateway (ex. Actisense NGT-1, etc.)

[Jim.Pope]

I am experiencing a similar problem with AIS targets never showing up or potentially disappearing.

System includes (3) e125 displays, each running V19.03 and ICOM M506 with AIS receiver. There is also a RS130 in the mix. All components are interfaced on NMEA 2000 network along with a number of Maretron products. No NMEA 2000 system anomalies except the e125's display of some received AIS targets. No NMEA 0183 connections to any of the equipment.

Similar to Robert's report, i have a PC running Coastal Explorer which is interfaced to the system via an Actisense NGT bridge. Coastal Explorer shows the same AIS targets listed on the ICOM AIS list. On the e125 units, some targets never appear.

We have been cruising with friends for the last couple of months and they have never shown up on our e125 while always showing up on the Coastal Explorer display. This is true whether we are next to each other or separated by several miles.

There are other examples of targets not showing up on the e125 while being present on Coastal Explorer. I simply highlight the one example as it is an example that is consistent and... easily reproduced.

I also suspect that there are cases of "disappearing" targets - although I am less confident of this observation given potential differences in how targets may be prioritized in high traffic areas, in / out of a cache, etc.

If it would be of any help to you, I believe it is possible to record a NMEA 2000 data stream with an Actisense pc tool. That might help determine if there is something in the AIS data that is causing this issue.

Of course, the best answer is that it is operator error and a configuration change on my end would solve the problem!

Many thanks for any help.

[Chuck - Raymarine - Moderator]

Jim,

It is recommended that ICOM support be contacted to you verify that your ICOM AIS receiver has been updated with the latest available Raymarine product software updates. If so and should the problem persist with an a/c/e/eS/gS-Series MFD operating with the Should the problem be occurring, then it would be recommended that the problem be duplicated and the Data Master MFD's NMEA 2000 logging feature be exercised when the problem occurs. Screen snapshots of the target lists of Coastal Explorer and the MFD would also be advised. It would also be worth querying Coastal Explorer's support team to determine how long targets persist after the targets's last position report is received.

[[email protected]]

Jim,

FYI I did remove the parallel connection of the AIS data from the PC system. It (tentatively) seems that the eS95 is now functioning as it should. While I did find one target where the name didn't show up, I recorded the MMSI and will contact them to see if they have programmed in their name. I think I know who they might be anyway. Otherwise, I've found several targets without names, checked the time, and within six minutes the name populated.

I'll keep looking at this, although will sometime add whatever is needed to allow the AIS250 to communicate with both the eS95 and the PC.

Robert

[Chuck - Raymarine - Moderator]

Noted.

[Jim.Pope]

After more careful review, I do not have problems with AIS targets disappearing inappropriately. My problem is that AIS Class B targets are not being displayed on my e125 connected to N2K network. Class A targets display as expected. Both Class A & B targets are displayed on a PC running Coastal Explorer.

To verify that the N2K messages were being received by the e125, I reviewed the attached log file in which I see 3 Class B Vessels that have transmitted the three Class B PGN's I would think would be sufficient to display the target. They are 129809 (Static B, Part A), 129810 (Static B, Part B) and 129039 (Class B Position). I have the entire log file, but it is 1.8 MB. The attached file is only the lines I believe are the messages for these PGN's & particular AIS targets.

For the three vessels, I believe the messages & times at which the messages appear in the log file are as follows: Since AIS messages are long, the complete message takes several lines in the log file and can be a few msecs from these time references below.

mmsi # 338006000
216.218 Part A
216.299 Part B
279.711 Position

mmsi # 338133193
252.516 Part A
254.383 Part B
343.208 Position

mmsi # 338151319
246.702 Part A
248.517 Part B
338.515 Position

These boats were transients in the same marina with my boat and continued to transmit their AIS data. Checking the ICOM 605 AIS list and Coastal Explorer over time showed the signal to be present, so it isn't a matter of signal loss. I also took photos of the e125 & Coastal Explorer displays showing the targets (or absence thereof). In a nearby harbor several Class A ships were present. I have photos showing how Coastal Explorer and the e125 both display the Class A targets correctly.

Hopefully this will provide some insight as to how to remedy my problem.

Thank you for the help.

[Chuck - Raymarine - Moderator]

Jim,

Within my earlier response, I had recommended that ICOM support be contacted to you verify that your ICOM AIS receiver has been updated with the latest available product software. As we have not been receiving problem reports from customers of other AIS receivers, it is strongly recommended that troubleshooting begin with the AIS receiver's software. Should the software within the AIS receiver be current, the SeaTalkng buffer should be configured to log only received PGNs. In the interim, the Forum's log file size will be increased to 5MB.