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Old 04-08-2015, 12:53   #16
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

travellerw,
I don't want to drift this thread into a debate regarding low-loss cable necessity...
(that's already been discussed to death...and have a look at these recent threads for some hard facts...
AIS Antenna on Spreaders

VHF and AIS Radiowave Propagation and VHF and AIS Radio Range )

But, if you're not using a "UF" suffix cable, you are causing yourself way too much frustration / hassle....(not to mention you're using a cable with copper-clad, solid aluminum wire center-conductor....rather than a stranded, copper center-conductor...)
Quote:
Originally Posted by colemj View Post
There is a flexible version of LMR400 that is more user-friendly. But it is still big cable.
Mark is correct here...

If you feel the need to use an ultra-low-loss cable, then please use the "UF" suffix versions....such as LMR-240UF, or LMR-400UF, or Bury-FlexUF, etc...


Have a look at the spec sheets for LMR-400 versus LMR-400UF....and you'll see the differences...

http://www.timesmicrowave.com/docume...es/LMR-400.pdf

http://www.timesmicrowave.com/docume...LMR-400-UF.pdf


I hope this helps some of you...

Fair winds...

John
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Old 04-08-2015, 20:23   #17
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

I'm using the UF suffix and it still sucks to pull. I've pulled a lot of cable in my life and this one just sucks. Although its flexible, its very thick and the outer coating is high friction. Trying to pull it in tight locations is very trying!

I agree the whole thing has been beat to death. My opinion after going through with it, is I should have just left the original cable in place. My radio reception was fine and I feel like I'm fixing something that wasn't broken. I guess time will tell if it was a worthwhile upgrade or not. We will see if I'm one of those people reporting 75 mile AIS targets (eye roll).
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Old 04-08-2015, 22:21   #18
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Wait.. I need to update this.. I just checked my cable and its NOT UF suffix.. Looks like standard Coper clad aluminum..

Even then, it not the flexibility that is the issue. Its just really thick and very high friction (loads of lube required). I spent some years pulling cable and dish soap works as good as most commercial lubes.

At this point, since I'm in for an OZ, I'm in for a pound. Tomorrow I pull it to the top so I will have %100 400 class cable!
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Old 09-12-2015, 16:31   #19
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

I'm thinking of buying a Standard Horizon GX2000 (~$200) & would appreciate more info about it. Earlier in this thread folks said that it could not receive GPS & AIS info on the same NMEA-0183 cable. Can anyone confirm/deny?
What appeals to me about this radio:
  • Better quality than most
  • AIS display so I don't have to turn on my CP
  • Speaker in mic (so I can hang it outside while we're sailing)
Comments on any of the above much appreciated. The VHF is usually mounted near our entryway, so it's easy to move the mic outside while we're underway, but I don't know about speaker volume or quality.
We have an AMEC class B AIS, but no display (or alarms) except our computer. I'm hoping the GX2000 will provide a (crude) display & alarm so we don't have to leave the computer on so much.
Thoughts? Comments? Better options? TIA!
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Old 09-12-2015, 20:05   #20
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Hi Jon,

Couldn't help it.... how about a WatchMate 750? Although it has an AIS receiver built-in, you can switch it off and feed both AIS and GPS from your existing transponder. Way better display of AIS with larger display, alarms, filtering, anchor watch and low power consumption. We've got a few factory reconditioned ones (perfect as new) on our website if you're interested.
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Old 10-12-2015, 00:30   #21
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Thanks, Jeff. It's not that I need an AIS display - I need a VHF! The squelch circuit on my trusty 15 year old Standard Horizon VHF went sideways & I lost sensitivity.

So I'm primarily looking for a good VHF. The GX2000 seems to be better quality (from their advertising blurbs) & it has the added benefit of a speaker in the mic, so we should be able to hear it outside when we're sailing. The AIS functionality is nice but really only #3 on the list.

But I don't really know the radio & was hoping others would chime in here.

I'd also like to know if Icom sells anything comparable (although I suspect they'll be more than $200).
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Old 10-12-2015, 01:01   #22
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Quote:
Originally Posted by jeffrobbins View Post
...your existing [AIS] transponder...
Jeff, since you're in the AIS business... An AIS is a radio - a transmitter/receiver, commonly shortened to transceiver. Nothing more. It does not respond to anything the way an aircraft transponder responds to a radar pulse. While I realize that "everyone" calls an AIS transceiver a transponder, I can't help thinking everyone's wrong. Since you're in a position to correct this misnomer, you might think about this...
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Old 10-12-2015, 05:46   #23
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Sorry Jon, I misunderstood what you were looking for. As far as I know the GX2000 doesn't accept a combined GPS & AIS data stream. At least that's how it used to work and they are at different baud rates. They changed it in their newer radios. Maybe one of the owners can confirm this.

Quote:
Originally Posted by Jon Hacking View Post
Jeff, since you're in the AIS business... An AIS is a radio - a transmitter/receiver, commonly shortened to transceiver. Nothing more. It does not respond to anything the way an aircraft transponder responds to a radar pulse. While I realize that "everyone" calls an AIS transceiver a transponder, I can't help thinking everyone's wrong. Since you're in a position to correct this misnomer, you might think about this...
Actually, it is fine to call it a transponder because it does respond directly to messages and queries transmitted by other stations. However, some people call it a transceiver since it's most often thought of the way you've described and most people aren't aware of what goes on behind the scenes. So the two terms for an AIS have become interchangeable but since most people tend to call it a transponder we adopted that nomenclature for our units.
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Old 10-12-2015, 23:18   #24
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Quote:
Originally Posted by jeffrobbins View Post
...Actually, it is fine to call it a transponder because it does respond directly to messages and queries transmitted by other stations...
Under what circumstances does a class-B AIS respond to outside messages or queries? I'm told a DSC VHF will sometimes respond to a position query (a huge security hole when transiting pirate waters, IMHO) but I didn't think AIS transmitted anything in response to an outside signal.
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Old 11-12-2015, 05:08   #25
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Quote:
Originally Posted by Jon Hacking View Post
I'm told a DSC VHF will sometimes respond to a position query (a huge security hole when transiting pirate waters, IMHO)
This can be set to manual response instead of auto response (and can be turned off completely). If so, it will not randomly respond to a request.

However, to get a position query, the person making the query needs the MMSI # of the vessel they want to query. It is difficult to imagine how pirates would have this information.

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Old 12-12-2015, 00:11   #26
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Thanks Mark. I *think* I turned that off with my last VHF, so as long as I turn off the AIS transmit functions as well (for MMSI discovery), we should be OK.

But my real question, in response to Jeff saying that an AIS was a transponder, was: under what conditions will an AIS-B transmit anything in response to an outside signal? AFAIK, they only broadcast on their own schedule (which varies by boat speed) but they don't actually respond to outside signals. Which would make it a transceiver, but not a transponder.
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Old 12-12-2015, 05:50   #27
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Quote:
Originally Posted by Jon Hacking View Post
Thanks Mark. I *think* I turned that off with my last VHF, so as long as I turn off the AIS transmit functions as well (for MMSI discovery), we should be OK.
Ummmm, if you have your AIS transmit turned on, then it would take very stupid pirates that would use that info to get your MMSI to use to make a VHF polling call to get a position report from your radio…

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Old 12-12-2015, 11:10   #28
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Quote:
Originally Posted by Jon Hacking View Post
... under what conditions will an AIS-B transmit anything in response to an outside signal? AFAIK, they only broadcast on their own schedule (which varies by boat speed) but they don't actually respond to outside signals. Which would make it a transceiver, but not a transponder.
C'mon guys. I bolded the real question earlier. Can't anyone tell me?

Under what conditions will an AIS-B transmit anything in response to an outside signal?
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Old 12-12-2015, 14:02   #29
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Well, Jeff made the statement that it does. I don't know, but transponder and transceiver has always been used interchangeably whenever I read anything about them.

Maybe they can respond to requests from harbor control stations? I think Class A can - even to the point of being shut down by harbor control.

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Old 12-12-2015, 20:38   #30
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Re: Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

Jon, and everyone,

Sorry to say, but the correct term here is "transponder"....
Although, I really don't care what you call it, "transponder" or "transceiver", here on a sailing website, we don't have to be 100% politically correct...

{However, if we are trying to provide accurate info, and actually educate our fellow sailors, shouldn't we strive to actually provide accurate info and educate with facts??? }


Now, you DO understand that Jeff runs a company full time, and might not have the time to respond to every minute query.....(especially one that seems a bit argumentative?? or condescending??)
So, if you allow me the "privilege" of answering you....

The answer is found in multiple locations in the ITU (and IMO, and USCG) docs....if you'd care to look...

The one that I find most on-point is, the 148-page ITU doc, ITU-R M.1371-5, titled " Technical characteristics for an automatic identification system using time division multiple access in the VHF maritime mobile frequency band"....

Yes, I know that you haven't read it, and most sailors probably wouldn't understand it, and there is no reason that they should!!!
And, don't worry I will not try to BS anyone with lots of "nomenclature", or buzz words...no....rather I'll just post one simple sentence, quoted from the ITU doc...

Quote:
"this system is autonomous, automatic, continuous and operate primarily in a broadcast, but also in an assigned and in an interrogation mode using time division multiple access (TDMA) techniques;"
{oh, and one thing often overlooked is the fact that "a controlling authority" can not only "interrogate" your transponder, but they can change its transmit timing, and even turn it off...and, yes, this too is explained in the supporting docs....
and, if you're wondering, in the US, the controlling authority is the USCG, DHS, or any agency the executive designates...
and, I suspect this is even more "controlling" in some other countries with more centralized gov't controls....
just saying, there ARE agencies/people, that DO "interrogate" AIS transponders regularly!}


There are a LOT of references to these being "transponders" in USCG docs, USCG websites, IMO docs and IMO sites, as well as the defining authority, the ITU and all their docs....so, if you wish to learn, all of this info is available for free on-line....all you need to do is look....
But, as I wrote, there's little need for most sailors to know all of this minutia!!

So, again....the correct term to use is "transponder".....but, as long as you understand that AIS transponders are transponders, you can call 'em whatever you like....


Fair winds...

John
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