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Post by georgia on Mar 11, 2019 12:49:13 GMT
Just an interesting bit of AIS technical trival.
After installing a vesper watchmate 2 transponder on my boat, my Garmin chartplotters show my boat and it’s ais “ghost” due to the fact that my VHF radio (an ICOM 506 VHF w/AIS receiver) is receiving my AIS transponder signals over the air.
The reason for this is that your transponder will track behind you, as the interval between updates from your AIS transponder will vary based on the speed of your boat. The faster you are moving the quicker the AIS transponder updates your position and data.
Therefore, the slower you go the more your boat's AIS "ghost" will appear further behind you if you have both an AIS transponder and a separate VHF or other AIS receiver.
I've dug through the ICOM 506 VHF AIS receiver options and can't find a way to simply "turn AIS receiving off".
I've dug through the Garmin Chartplotter manual and can't find a way to "ignore or remove MY boat's target data"
I've dug through the Vesper Watchmate 2 manual and can't find a way to "turn off sending MY boat's target data to the NMEA2000 onboard network."
Just curious if anyone else has this issue or a resolution to it.
I'm chatting with both gramin and vesper to find a resolution for this moderately annoying issue.
cheers
geo
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Post by Caxton on Mar 11, 2019 16:27:27 GMT
My guess is you have to disconnect the NMEA output wire from your ICOM. The ICOM doesn't know you are transmitting a AIS signal and thinks your signal is another boat. Your Garmin is plotting AIS data it receives (excluding its own transmitted signal) and transmits your data.
Originally I had my Standard Horizon GX6500 VHF provide NMEA AIS data to my Raymarine Chartplotter. When I installed a Raymarine AIS 650 transponder, I disconnected the output from the GX6500 and used only the AIS650 for input to the chartplotter.
Caxton
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Post by sitara on Mar 11, 2019 20:46:11 GMT
Not relevant to this discussion but I once had an AIS ghost that I assume was caused by reflections from some nearby hills. Never happened again.
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Post by zaphod on Mar 11, 2019 21:07:01 GMT
My guess is you have to disconnect the NMEA output wire from your ICOM. The ICOM doesn't know you are transmitting a AIS signal and thinks your signal is another boat. Your Garmin is plotting AIS data it receives (excluding its own transmitted signal) and transmits your data. Originally I had my Standard Horizon GX6500 VHF provide NMEA AIS data to my Raymarine Chartplotter. When I installed a Raymarine AIS 650 transponder, I disconnected the output from the GX6500 and used only the AIS650 for input to the chartplotter. Caxton The only problem with that is that you may disable DSC communication between the VHF and the chart plotter. My Standard Horizon VHF combines the DSC with the AIS data on the NMEA HS (high speed) port. If you disconnect that, you may need to connect the DSC connections of your VHF to one of your standard 4800 baud ports on your chart plotter. That way your VHF will still have position information from the GPS, and will be able to plot DSC data from the vhf. Again, this is based on what I learned about my standard horizon radio, your Icom may be different. Read your manual before you start cutting wires. |
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Post by georgia on Mar 11, 2019 22:42:57 GMT
found the answer after chatting with ICOM engineers and VESPER engineers... The Vesper Watchmate 2 does not send "own" vessel data as a target, but the ICOM is picking up the AIS's transmitted data and displaying it. The engineers at ICOM showed me where , on a deep dive, the solution was located.
press Menu on front panel.
select AIS set
go to ID blocking and enter
Press ADD
enter "Own boat's" MMSI number
press enter
this will allow the secondary receiver of the ICOM 506 to ignore your own MMSI number and it eliminates the AIS "Ghost"....
I'm pretty sure other high end VHD units that pick up AIS can do the same.
cheers
geo
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Post by Mistroma on Mar 11, 2019 22:50:51 GMT
This rings a very faint bell. I have a COMAR AIS which uses the same PC software as the Raymarine AIS650 and I believe both units use the same basic hardware. I remember seeing a Raymarine software update notification to resolve something similar to this situation (probably at least 5 years ago). The ship's own MMSI was being received back from AIS repeater base stations. The plotter was then showing your own vessel as a target following itself on a Raymarine MFD or a third party chartplotter. The fact that it wasn't restricted to Raymarine plotters made me think that there must be a NMEA sentence saying "ignore MMSI nnnnnn as it's me". I remember thinking that the AIS wouldn't receive my own MMSI, just transmit it. I'll do a little digging if I have time. EDIT: I stumbled across the information more quickly than expected. Link hereV1.6, 2012
Own MMSI received back from AIS repeater base stations, this manifests itself as own vessel target following itself on a Raymarine MFD or third party chartplotter.I doubt it's relevant unless you have a very old AIS as it must have been fixed on all modern sets. |
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Post by NZL50505 on Mar 11, 2019 23:33:44 GMT
Just an interesting bit of AIS technical trival. After installing a vesper watchmate 2 transponder on my boat, my Garmin chartplotters show my boat and it’s ais “ghost” due to the fact that my VHF radio (an ICOM 506 VHF w/AIS receiver) is receiving my AIS transponder signals over the air. The reason for this is that your transponder will track behind you, as the interval between updates from your AIS transponder will vary based on the speed of your boat. The faster you are moving the quicker the AIS transponder updates your position and data. Therefore, the slower you go the more your boat's AIS "ghost" will appear further behind you if you have both an AIS transponder and a separate VHF or other AIS receiver. I've dug through the ICOM 506 VHF AIS receiver options and can't find a way to simply "turn AIS receiving off". I've dug through the Garmin Chartplotter manual and can't find a way to "ignore or remove MY boat's target data" I've dug through the Vesper Watchmate 2 manual and can't find a way to "turn off sending MY boat's target data to the NMEA2000 onboard network." Just curious if anyone else has this issue or a resolution to it. I'm chatting with both gramin and vesper to find a resolution for this moderately annoying issue. cheers geo
Co-incidentally I've literally just started getting this exact same problem after my system had been running fine for over a year since it was installed (Vesper connected to Raymarine MFD & VHF). So something has changed in the settings of one of the devices and I can't work it out - will have to get my marine electronics guys who installed it last year to take a look and show me how to fix myself in case it happens again.
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Post by NZL50505 on Mar 12, 2019 8:04:47 GMT
Looks like I might have fixed it. Turns out my guys did some routine maintenance last week including upgrading software on all my gear - and it caused my Raymarine VHF to switch AIS on which I don’t want because I have full send & receive being handled by Vesper. Which led to duplicate ‘ghost’ AIS image. Will test more thoroughly over weekend but provisionally promising.
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Post by chuckr on Mar 17, 2019 11:09:06 GMT
Are you using a splitter? We have been using AIS for the past 11 years and never had this issue. BUT we have a separate gps and ais antenna - I am not a believer in splitters. sorry just an old guy who believes each unit should function for it self and not share.
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Post by NZL50505 on Mar 19, 2019 9:19:33 GMT
Are you using a splitter? We have been using AIS for the past 11 years and never had this issue. BUT we have a separate gps and ais antenna - I am not a believer in splitters. sorry just an old guy who believes each unit should function for it self and not share. Separate. Here in NZ it’s not permitted to install AIS and GPS on same anteanna. |
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Post by Don Reaves on Mar 19, 2019 19:00:08 GMT
Typically, AIS and VHF share an antenna using a splitter. Not AIS and GPS.
Did you mean to say that NZ prohibits installing AIS and VHF on the same antenna?
Don
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Post by Caxton on Mar 19, 2019 19:15:14 GMT
To pile on, its definitely required in the US to have an independent GPS antenna for AIS. Using a splitter for VHF/AIS transmit works fine but you can increase your range if you buy a hybrid antenna. I use a Vesper VA159 AIS/VHF Antenna
with my Raymarine AIS 100 and AIS650.
Caxton
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