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Old 10-04-2013, 19:58   #76
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Now Jedi,

I did say from 400 to 600.

Now with the splitter you must have, according to jeff, an ais compatible VHF antenna. Now since starting to outfit the boat for offshore I have discovered that God does not like me, so I can categorically state that my 15 year old vhf antenna is not AIS compatible. Now that means 80ft of cable. Hows the math looking now! I also did state that cost into my hands. Us Canadians gladly pay a further 14% tax. If it has to be shipped by FED or UPS another wallop for "border" handling, even when no duty payable.

I like the whole idea of the Vesper system and I would love it if someone bought me one for Christmas. It all is a question of cost right now. What to buy what do I leave behind.
If you deem your antenna good enough for your vhf, then it is good enough for ais. I am pretty hardcore VHF to microwave engineer type and disagree with the need for special AIS antennas. AIS is on standard VHF channels and will work 100% on any VHF antenna.

So, get ready to order the AIS and splitter but just wait until you're out of Canada and get it in the US so you save costs.
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Old 10-04-2013, 20:17   #77
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Re: Want the Best, Cheapest Easiest AIS solution:-)

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Now with the splitter you must have, according to jeff, an ais compatible VHF antenna. Now since starting to outfit the boat for offshore I have discovered that God does not like me, so I can categorically state that my 15 year old vhf antenna is not AIS compatible. Now that means 80ft of cable.
I don't believe I would have said you had to have an AIS-tuned antenna. However, I would say you need a well functioning VHF antenna system. The vast majority of problems and poor performance with AIS systems is due to poor antenna systems (antennas/cables/connectors).

My own personal advice for what it's worth, having nothing to do with AIS, is if your masthead antenna isn't working or giving good performance for your VHF radio, then that ought to be a high priority regardless.
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Old 10-04-2013, 20:21   #78
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Re: Want the Best, Cheapest Easiest AIS solution:-)

If you don't need a transponder, or NMEA2000, or WiFi, then the Standard Horizon AIS+ 2150 is cheap and easy.

Just replace your existing VHF with it, connect a GPS feed and you're done.

No new antenna, no splitter, has a display and alarm built in.

$300 on sale (with mail in rebate) and free shipping from a Canadian store:

STANDARD VHF MATRIX+ with AIS GX2150S Binnacle.com
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Old 10-04-2013, 20:52   #79
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Re: Want the Best, Cheapest Easiest AIS solution:-)

from jedi If you deem your antenna good enough for your vhf, then it is good enough for ais. I am pretty hardcore VHF to microwave engineer type and disagree with the need for special AIS antennas. AIS is on standard VHF channels and will work 100% on any VHF antenna.

Chi-ching,( money saving advice) Always said a Mazda can run on 3 wheels:-) So un-technically speaking, if my vhf works so should the AIS. Just splitter and a couple of cables.
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Old 10-04-2013, 22:21   #80
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Re: Want the Best, Cheapest Easiest AIS solution:-)

You can probably save money by sailing bare-bones to Seattle and shopping American, too.
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Old 11-04-2013, 06:10   #81
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Quote:
Originally Posted by NorthPacific View Post
from jedi If you deem your antenna good enough for your vhf, then it is good enough for ais. I am pretty hardcore VHF to microwave engineer type and disagree with the need for special AIS antennas. AIS is on standard VHF channels and will work 100% on any VHF antenna.

Chi-ching,( money saving advice) Always said a Mazda can run on 3 wheels:-) So un-technically speaking, if my vhf works so should the AIS. Just splitter and a couple of cables.
Correct. But I also agree with Jeff that your VHF antenna installation is suspect unless professionally installed within the past 5 years or so You can save money on many things, but not all things. Make sure this stuff works good and reliably.
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Old 11-04-2013, 06:28   #82
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Re: Want the Best, Cheapest Easiest AIS solution:-)

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If you deem your antenna good enough for your vhf, then it is good enough for ais. I am pretty hardcore VHF to microwave engineer type and disagree with the need for special AIS antennas. AIS is on standard VHF channels and will work 100% on any VHF antenna.

So, get ready to order the AIS and splitter but just wait until you're out of Canada and get it in the US so you save costs.
I guess 'good enough' is in the eye of the beholder. AIS works on channels 87B (161.975 MHz) and 88B (162.025 MHz), the very upper end of the marine vhf band.

Normal marine vhf antennas are tuned for ~157 MHz.

As advertised by Shakespeare for their marine vhf 5' fiberglass whip with 3db gain - SWR: nominally 1.5:1 at 156.8 MHz; Bandwidth: 5 MHz within 2.0:1 VSWR. So that equates to anything outside of 154.3 to 159.3 to have SWR higher than 2.0:1 (plus coax/connection loss).

Shakespeare's AIS antenna is advertised at: SWR: nominally 1.5:1 at 162 MHz; Bandwidth: 6 MHz within 2.0:1 VSWR (I'm using this antenna and measuring 1.2:1)

A review of other manufacturers marine vhf antennas showed similar specs.

Using the info below, an example of a SWR of 3.0:1, you lose 25% of the effective radiated power.

SWR LOSS
1.0:1 0.0%
1.1:1 0.2%
1.2:1 0.8%
1.3:1 1.7%
1.4:1 2.8%
1.5:1 4.0%
1.6:1 5.3%
1.7:1 6.7%
1.8:1 8.2%
2.0:1 11.1%
2.2:1 14.1%
2.4:1 17.0%
2.6:1 19.8%
3.0:1 25.0%
4.0:1 36.0%
5.0:1 44.4%
6.0:1 51.0%
7.0:1 56.3%
8.0:1 60.5%
9.0:1 64.0%
10.0:1 66.9%

The question left to answer is how much distance is lost transmitting at 2W (AIS class B) with an ERP of 75%?

If other factors ($$, mounting location, etc.) are added to the mix, yes, your normal marine vhf antenna with an antenna splitter will be 'good enough', but certainly not optimal (not 100%).
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Old 11-04-2013, 09:14   #83
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Re: Want the Best, Cheapest Easiest AIS solution:-)

An installer told me he has seen problems with the splitter degrading or interfering with VHF functionality. Don't know if this was just to sell an entire separate AIS antenna, wiring and install, but has anyone else seen or heard of this?
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Old 11-04-2013, 11:01   #84
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Re: Want the Best, Cheapest Easiest AIS solution:-)

Bloody Hell!

I am just going to strap the Mrs to the mast head!!!!

How many people who use AIS now, replaced their VHF antenna or setup a sep. AIS antenna.
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Old 11-04-2013, 11:10   #85
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Re: Want the Best, Cheapest Easiest AIS solution:-)

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An installer told me he has seen problems with the splitter degrading or interfering with VHF functionality. Don't know if this was just to sell an entire separate AIS antenna, wiring and install, but has anyone else seen or heard of this?
Yes. The same thing can happen when you split a VHF antenna for a VHF and an FM car radio receiver.

All things being equal, and as my SSB installation knowledge improves, there is a strong case to be made for separate AIS and VHF antennas, with the AIS one optimized for its rather specific frequencies.

But half a loaf is better than none with AIS. It's skipper's choice.
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Old 11-04-2013, 11:14   #86
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Re: Want the Best, Cheapest Easiest AIS solution:-)

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Bloody Hell!

I am just going to strap the Mrs to the mast head!!!!

How many people who use AIS now, replaced their VHF antenna or setup a sep. AIS antenna.
I'm sure she'll want a bracing rum beverage before that task!

NP, yes, this topic is complex, but even if you opt for "simpler, cheaper" over "best", you will at least understand where the goal posts are for the technology.

I have yet to install an AIS, because, like RADAR, it's one of the last things I wish to buy before we push off, so I can have the benefits of the rapid advances and (in some cases) the increased affordability. But I consider myself informed on my options. Panbo.com is a good resource in this regard if you are finding this thread frustrating.
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Old 11-04-2013, 13:15   #87
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Re: Want the Best, Cheapest Easiest AIS solution:-)

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I guess 'good enough' is in the eye of the beholder. AIS works on channels 87B (161.975 MHz) and 88B (162.025 MHz), the very upper end of the marine vhf band.

...

If other factors ($$, mounting location, etc.) are added to the mix, yes, your normal marine vhf antenna with an antenna splitter will be 'good enough', but certainly not optimal (not 100%).
Yes, I completely agree. That's why when people ask me for a recommendation and cost is the driving factor, I tell them an existing well functioning VHF antenna will work. But when performance is a factor, I recommend they consider an AIS-tuned antenna. If the existing masthead antenna is old, or of unknown origin, I recommend changing it, or at least professionally checking it.

So... if you are going to change it, then I recommend considering an AIS-tuned one. AIS-tuned antennas usually have around 6-7MHz of bandwidth so they will still work well with the VHF radio which has much higher power output. But they are optimized for 162MHz to be used with the much lower power output AIS.

Regards the signal loss due to splitters... that's quite true of most splitter designs. Most "designed for AIS" splitters have over 4dB of loss (that takes your 25W VHF and radiates 9W or less). We looked at this and designed a splitter that has virtually no loss on the VHF path and has 12dB of amplification on the AIS receive path. This results in an effective 6dB gain in sensitivity for our AIS units. It more than makes up for the longer cable run up the mast and combined with the antenna height results in significantly increased AIS receive range.
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Old 11-04-2013, 13:20   #88
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Re: Want the Best, Cheapest Easiest AIS solution:-)

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All things being equal, and as my SSB installation knowledge improves, there is a strong case to be made for separate AIS and VHF antennas, with the AIS one optimized for its rather specific frequencies.
I also agree with this. But it requires you have a good mounting location for the AIS antenna. Ideally it needs to be in "free space", as high as possible, and several meters from any other antennas, mast, rigging, etc. Often this has to be compromised and as a result the dedicated antenna may not perform as well and you would be better off using a less well tuned antenna but mounted in a more optimal position.
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Old 11-04-2013, 15:35   #89
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For just receive we love our Standard Horizon Matrix 2150. I almost wish we would have bought a unit with a transmitter, but our Matrix is great and doesn't require another antenna.
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Old 11-04-2013, 16:54   #90
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Re: Want the Best, Cheapest Easiest AIS solution:-)

Having only one mast and limited real estate atop it I am fearful to ask where I should put the new antenna? :-)

MAybe change the point of attack. Does anyone have an AIS system they do not ? Something to stay away from. How important is it to transmit your own position. If you pick up a vessel that is a threat would you not phone and give your position? How important for safety in the open ocean is the transmit facility with Ais?
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