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Old 21-06-2013, 11:01   #31
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Re: considering an ais transponder, any recommendations?

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Originally Posted by savoir View Post
..... The only one I know of that can is the Raymarine AIS650. The others force you to feed data into the AIS from its own GPS antenna. They cannot communicate with your network antenna so you must thread yet another wire and drill yet another hole. The only possible communication with the network is data out....
I interpret what you wrote as claiming the RM AIS650 will use a network GPS in place of it's internal GPS??

AFAIK, this is against all rules. Transceivers must use their own GPS (to prevent location spoofing).

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Old 21-06-2013, 11:08   #32
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Re: considering an ais transponder, any recommendations?

I wasnt aware that the AIS650 can use seatalkng GPS data, I mean it ships with its own integral GPS unit!!!

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Old 21-06-2013, 11:11   #33
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Re: considering an ais transponder, any recommendations?

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yes but with a transceiver, its always good to try and get your class B signal to travel as far as possible. I mean if you have a fast cat at 40kts closing , wouldnt you want him to see you on HIS AIS as far away as possible.

SO why arbitrarily limit the range, The mast head antenna on most boats spends 99% of its time doing nothing, using a splitter and a high antenna maximises its use and the usability of an AIS transceiver.

Arguing about mast coming down is nonsense. Ive seen failing masts take out the whole radar arch electronics . Anyway you can make a VHF antenna by striping a piece of co-ax and a broom handle.

Those arguing that a day to day benefit shouldn't be utilised becuase a rare failure event will render it inoperable, I mean how do these people get in a car or an aircraft!!!.


dave
Agree, the mast falling down argument is nonsense.

So, what is your suggestion to the 40' power boat with a radar arch 12' off the water. Install a 40' mast?

My point is the system is designed to work in these scenarios.

I certainly agree with what you are saying. I decided to sacrifice range for simplicity. I decided the extra range would cover far less than 1% of instances that *could* result in a TCPA alarm. I traded that .xxx% for simplicity and cost. Complexity adds failure points.

I did think about MarkJ's suggestion as I like it best. And if I could find a reasonable PL258 X-switch, I would probably buy it!
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Old 21-06-2013, 11:16   #34
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Re: considering an ais transponder, any recommendations?

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So, what is your suggestion to the 40' power boat with a radar arch 12' off the water. Install a 40' mast?
of course not, just that any height helps
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Old 21-06-2013, 11:33   #35
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Re: considering an ais transponder, any recommendations?

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Originally Posted by goboatingnow View Post
which cheap splitters do you mean, all the ones Ive seen are around the 200 mark and are designed for AIS.

AIS and N2k, This is a moving dot, because since NMEA have belatedly released the PGN for static data, most AIS system are being updated, so you rcomments dont hold true in general anymore. for example SIMRAD is now N2K compatible.

Also note that Raymarine is only compatible with C/E wide series only and requires the latest software.

as for units with integrated GPS and antenns, like the Vesper 850, they will work in the cabin with only the fibreglass cabin top in the way


Dave
There are so many cheap splitters out there that Idon't know all the brands but most are intended for a commercial radio/VHF split. Chances are they all come from the same factory in China anyway. The ones I know are branded Comar, Shakespeare and Digital Yacht. Even some of the more expensive units such as Furuno and Simrad won't let you use VHF transmit and AIS at the same time. The transmission will block the AIS.

Simrad AIS definitely cannot be fully networked with NMEA 2000. It will work on data out only. For data in you must provide it with its own isolated GPS antenna. The same applies to the Lowrance and B & G units which are identical. If a row of mushrooms on your transom is OK with you then so be it.

The form of chart preferred by Raymarine equipment is not relevant because the GPS antenna on the AIS will never be asked to provide data for chartplotting functions unless you choose to make it the principal antenna for the boat.
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Old 21-06-2013, 11:34   #36
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Re: considering an ais transponder, any recommendations?

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of course not, just that any height helps
To carry this idea a little further.

My stern rail mounted AIS antenna is 8' off the water, tuned for 162mhz (AIS freq), 3db gain, connected with ~30' of RG58.

My mast antenna is 65' off the water, is tuned for 156.8mhz, 3db gain, connected ~85' of RG8X.

My AIS unit's internal diagnostics are reporting a VSWR of 1.0:1 using the stern rail antenna. Without testing it, let's assume that would change to 3.0:1 if I were to connect to the mast head antenna (cable distance, mal-tuned antenna, etc.).

Care to comment about how much range would increase?

I'm asking as I really don't know...and I'm too lazy to cut wire ties, pull slack, etc. to test.
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Old 21-06-2013, 11:38   #37
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Re: considering an ais transponder, any recommendations?

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Originally Posted by savoir View Post
There are so many cheap splitters out there that Idon't know all the brands but most are intended for a commercial radio/VHF split. Chances are they all come from the same factory in China anyway. The ones I know are branded Comar, Shakespeare and Digital Yacht. Even some of the more expensive units such as Furuno and Simrad won't let you use VHF transmit and AIS at the same time. The transmission will block the AIS.

Simrad AIS definitely cannot be fully networked with NMEA 2000. It will work on data out only. For data in you must provide it with its own isolated GPS antenna. The same applies to the Lowrance and B & G units which are identical. If a row of mushrooms on your transom is OK with you then so be it.

The form of chart preferred by Raymarine equipment is not relevant because the GPS antenna on the AIS will never be asked to provide data for chartplotting functions unless you choose to make it the principal antenna for the boat.
I think you have teh wrong end of teh stick here.

No Splitter allows simultaneous use of VHF and AIS, the VHF overrides the AIS TX. Are you saying Digital yacht is a cheap splitter. Again are you talking about semi-automatic VHF1-2 switches or something.

Quote:
"Simrad AIS definitely cannot be fully networked with NMEA 2000. It will work on data out only"
Thats the way its supposed to work, the spec says it must be powered by its own GPS. Thats why I believe you are wrong with Ray AIS650, it cannot use seatalkng GPS signals. certainly Ive installed and setup two and they always use the internal GPS.

Quote:
The form of chart preferred by Raymarine equipment is not relevant because the GPS antenna on the AIS will never be asked to provide data for chartplotting functions unless you choose to make it the principal antenna for the boat
I never mentioned this, so what, you can have 6,8,10 GPS units on board, there as cheap as chips.

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Old 21-06-2013, 11:39   #38
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Re: considering an ais transponder, any recommendations?

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Originally Posted by DotDun View Post
I interpret what you wrote as claiming the RM AIS650 will use a network GPS in place of it's internal GPS??

AFAIK, this is against all rules. Transceivers must use their own GPS (to prevent location spoofing).


The operative word is " antenna " not " GPS ". A RM650 will accept data in from a network antenna that is connected to the backbone cable. Simrad/ B & G/ Lowrance/ Furuno ( and probably a few others ) will not.
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Old 21-06-2013, 11:40   #39
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Re: considering an ais transponder, any recommendations?

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Originally Posted by DotDun View Post
To carry this idea a little further.

My stern rail mounted AIS antenna is 8' off the water, tuned for 162mhz (AIS freq), 3db gain, connected with ~30' of RG58.

My mast antenna is 65' off the water, is tuned for 156.8mhz, 3db gain, connected ~85' of RG8X.

My AIS unit's internal diagnostics are reporting a VSWR of 1.0:1 using the stern rail antenna. Without testing it, let's assume that would change to 3.0:1 if I were to connect to the mast head antenna (cable distance, mal-tuned antenna, etc.).

Care to comment about how much range would increase?

I'm asking as I really don't know...and I'm too lazy to cut wire ties, pull slack, etc. to test.
I cant give you a quantitative answer, but the experience related here and from others is that mast head AIS , i.e. sharing the antenna gives the best range, VHF range is highly sensitive to height rather then power.

dave
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Old 21-06-2013, 11:41   #40
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Re: considering an ais transponder, any recommendations?

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Originally Posted by savoir View Post
The operative word is " antenna " not " GPS ". A RM650 will accept data in from a network antenna that is connected to the backbone cable. Simrad/ B & G/ Lowrance/ Furuno ( and probably a few others ) will not.

whats a networked "antenna"

sorry savoir, I do believe genuinely you have the wrong end of the stick

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Old 21-06-2013, 11:43   #41
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Re: considering an ais transponder, any recommendations?

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Originally Posted by Dockhead View Post
If your VHF signal can only be heard 12 miles out from an antenna 65 feet above the water, then I think you have antenna, or more likely, cable/connector problems. Even with my old antenna, I was getting excellent signal reports from 60 miles away, provided the other antenna was high enough (Solent Coast Guard from Cherbourg). Talk to ships 30 to 40 miles away. I presume you have a normal, 25 watt transceiver?
Dockhead...

I wasn't talking about my VHF radio, I was talking about the distances my Class B AIS Unit transmits using the boat's VHF masthead antenna...

My VHF Radio transmits just fine thank you
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Old 21-06-2013, 11:46   #42
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Re: considering an ais transponder, any recommendations?

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Originally Posted by goboatingnow View Post
I cant give you a quantitative answer, but the experience related here and from others is that mast head AIS , i.e. sharing the antenna gives the best range, VHF range is highly sensitive to height rather then power.

dave
fair enough!
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Old 21-06-2013, 11:51   #43
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Re: considering an ais transponder, any recommendations?

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Dockhead...

I wasn't talking about my VHF radio, I was talking about the distances my Class B AIS Unit transmits using the boat's VHF masthead antenna...

My VHF Radio transmits just fine thank you
OK, thanks for clearing that up
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Old 21-06-2013, 11:56   #44
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Re: considering an ais transponder, any recommendations?

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I also assumed that jerimiahson was describing his 3-Watt Class-B AIS transmit range. But this is ambiguous. And even an A/B test of VHF range will be questionable, since there are so many other uncontrolled variables.
Just FYI - AIS Class B transmits at 2 watts, not 3...

Yes, you are correct that many things effect VHF transmissions, but what I was trying to relate was that testing my AIS Class B Unit on two different antennas got very different results, with higher antenna producing a significantly longer range.

No, it wasn't a scientific test, it was me calling a couple buddies of mine who were operating tourist ferries on San Francisco Bay while I was parked at the dock. They were able to see my AIS signal on there receivers while they drove towards the GG Bridge.

The distances were easy since they were displayed when they lost my signal, but since they were traveling at 15 knots and my stationary boat was transmitting every 30 seconds I added a fudge factor of a mile. They reported losing my signal at 11 miles on the taller antenna.
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Old 21-06-2013, 11:57   #45
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Re: considering an ais transponder, any recommendations?

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Originally Posted by goboatingnow View Post
whats a networked "antenna"

sorry savoir, I do believe genuinely you have the wrong end of the stick

dave
A networked antenna is one that acts as the antenna for and provides data to every component in the network. The Simrad NAIS 400 and the identical Lowrance/ B & G units cannot accept signal from any such antenna.

As for " I never mentioned this " try your post 24

" Also note that Raymarine is only compatible with C/E wide series only and requires the latest software. "
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