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Standard GX2150 AIS Limitation

Old 09-22-2011, 11:49 PM
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Default Standard GX2150 AIS Limitation

Recently discovered that the GX2150 has a built-in limitation where it will only search and display AIS targets within a 15 mile range.
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Old 09-23-2011, 08:13 AM
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That's about the physical limit of the receive capabilities anyway, isn't it? And, who cares what's beyond 15 miles, unless your going 200 MPH?
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Old 09-23-2011, 08:28 AM
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Originally Posted by Birdman View Post
That's about the physical limit of the receive capabilities anyway, isn't it? And, who cares what's beyond 15 miles, unless your going 200 MPH?
Not by a long shot. I've seen vessels list out to 100 miles. Now realistically, I don't care since I use it for collision avoidance, but if I were using it to find specific boats while fishing, I might. I might also care if I ran at 40-50 knots. As it is 15 miles gives me a lot of warning.

In any case, my ACR unit doesn't do that. As long as the vhf signal can reach me somehow, it will display it.
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Old 09-23-2011, 08:33 AM
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k7, you sure it's nto a software setting?
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Old 09-23-2011, 08:58 AM
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According to the manual, 15nm is the max range setting for the display and the max activation range is 20nm (default is 10nm). RTFM

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Old 09-23-2011, 09:30 AM
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Hmm, I wonder if it has the same limitation when feeding a CP instead of it's own display?

I can see why they would limit the display, not much real estate to work with. But do they do it when sending data out nmea to a chartplotter?
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Old 09-23-2011, 09:58 AM
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While I have a 2100 instead of a 2150, I can tell you that targets as far as 100 miles are displayed on my chart plotter, which sets it's own alarms. But at 8 knots, I'm not amused by 3 hour TCPA alarms.
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Old 09-23-2011, 10:00 AM
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I was wondering the same thing. Would like to get my hands on one for some testing. The manual states: Activation Range, the range the receiver searches for targets. Max setting is 20nm but I see a graphic in the manual showing the AIS screen that conflicts with wording in the manual. It shows display range as 50nm and the selected target at 26.8nm

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Old 09-23-2011, 10:22 AM
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I see no reason they would limit reception in the hardware, so I suspect they are talking about firmware or software treatment of the available data, likely in the display only.

I have a question: who would buy this radio and not connect it to a chart plotter, and why? You have to do that for DSC and Rescue 21 anyway.
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Old 09-23-2011, 10:34 AM
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Originally Posted by sandyda View Post
I see no reason they would limit reception in the hardware, so I suspect they are talking about firmware or software treatment of the available data, likely in the display only.

I have a question: who would buy this radio and not connect it to a chart plotter, and why? You have to do that for DSC and Rescue 21 anyway.
I'd be willing to bet that a very high percentage of DSC capable radios aren't connected to a CP. Heck, I'd be willing to say most aren't even connected to a GPS.
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Old 09-23-2011, 10:38 AM
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I'm afraid you're right, Gerg. I've been running around wiring up the boats in my club, for free, and some of these guys won't bother at even that price! I didn't realize how many old farts are just as bullet-proof as a teenager! You should hear some of the excuses....
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Old 09-23-2011, 10:49 AM
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Formula is LOS = 1.23*(sqrt(H1)+sqrt(H2))

LOS is nm....H1 and H2 are in feet. So........H1 is a commercial vessel with an AIS antenna at 100 feet off the deck. Us kids are recreational with antenna say 10 feet off the deck.

LOS is 16.2 nm. And that's under perfect conditions.
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Old 09-23-2011, 12:03 PM
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Originally Posted by gerg View Post
I'd be willing to bet that a very high percentage of DSC capable radios aren't connected to a CP. Heck, I'd be willing to say most aren't even connected to a GPS.




Mine is and works great! Connected to both my Standard Horizon gps's, cp500 & cp180. I get a programmed pop up alarm on both gps's when the target ship approaches my preset distance.
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Old 09-23-2011, 02:00 PM
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Originally Posted by capecuddy View Post
Formula is LOS = 1.23*(sqrt(H1)+sqrt(H2))

LOS is nm....H1 and H2 are in feet. So........H1 is a commercial vessel with an AIS antenna at 100 feet off the deck. Us kids are recreational with antenna say 10 feet off the deck.

LOS is 16.2 nm. And that's under perfect conditions.

That's what I was trying to point out.

Sure, gerg and others can say "I get targets a 100 miles away all the time!!". BUT, what they DON'T know is, there are 100's of targets, 100 miles away, that they are NOT getting.

As with VHF transmissions, sometimes in certain conditions, you get some long range comm's, but it's not something to rely on. I'm guessing, but that's probably what the manual is trying to say: "The realistic working range of this unit is about 15 miles".
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Old 09-23-2011, 03:38 PM
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I already said that realistically speaking it wouldn't matter if I didn't see vessels that were more than 20 miles away. Generally speaking, I don't have my CP zoomed out that far unless I'm well offshore.

But some of the 100 foot tall vhf xmitters are attached to 300 foot plus ships moving at 25-30 knots. I do want to know where they are, which direction they are heading, and how far out they are if I am offshore. If we are heading towards each other at full cruise, that's less than 30 minutes of warning, and probably less than 15.

If I need to get an anchor in, or get lines in and start engines, I'd like warning.

I'm not saying 20 miles is a show stopper, but if the data is there I'd want to see it.
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Old 09-23-2011, 05:54 PM
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Read the GX-2150 manual carefully. The 15 mile limit appears to be applicable to the display on the radio. There is something in the setup called activation range and it goes out to 50 miles. With all respect to a great GX-2150 product (which I own), I'm not about to look at more than 15 miles worth of AIS targets on a postage stamp size display. That's what the NMEA0183 interface to my HDS-10 is for.
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Old 09-24-2011, 08:53 AM
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The coast Guard released an update on DSC that's pretty dismal. See new thread.
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