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Discussion Starter #1
OK guys, especially the ellectronics gurus here...I really need your help with a question, please.

I have a Garmmin 185C GPS on my boat, that has it's dedicated antenna, that was embedded in the deck for low profile.

Now, as most know I have a radar I am installing, and that has GPS feature.

My question is, do I need a dedicated antenna for the raymarine or I can "tap" off the Garmin's antenna??

If I can what wire and connectors should I use.

I hate having to drill holes on my boat for a second GPS antenna..that's why I ask.

Thank you for your responses

Alex
 

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Yes, you probably need to have Raymarine's GPS antenna. I doubt that the two brands are interchangeable. :)
 

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Giu,


Most GPS devices have an output connector, which allows you to connect other devices which can make use of the positioning information. This usually takes place via standard NMEA connections.

The Garmin GPSMAP 185C Sounder supports up to 3 NMEA devices. The following is from Appendix A of the Garmin manual,

"NMEA Formats
The following formats are supported for connection to up to 3 NMEA devices:
. NMEA 0180/NMEA0182
. NMEA 0183 version 1.5
. NMEA 0183 version 2.0"

So, you hook the output of the 185C to your Raymarine, and you should be good to go.

By the way, apropos of your other recent post, you'll want to be sure that the AWG18/2 wire connecting the Garmin to the radar is approved by Garmin, Raymarine, the NMEA, the ABYC, the EU, and other appropriate regulatory bodies :) In my experience, this should not take longer than about six months. No doubt Dog will also want a piece of the action!

Bill
 

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Giu,


Most GPS devices have an output connector, which allows you to connect other devices which can make use of the positioning information. This usually takes place via standard NMEA connections.

The Garmin GPSMAP 185C Sounder supports up to 3 NMEA devices. The following is from Appendix A of the Garmin manual,

"NMEA Formats
The following formats are supported for connection to up to 3 NMEA devices:
. NMEA 0180/NMEA0182
. NMEA 0183 version 1.5
. NMEA 0183 version 2.0"

So, you hook the output of the 185C to your Raymarine, and you should be good to go.

By the way, apropos of your other recent post, you'll want to be sure that the AWG18/2 wire connecting the Garmin to the radar is approved by Garmin, Raymarine, the NMEA, the ABYC, the EU, and other appropriate regulatory bodies :) In my experience, this should not take longer than about six months. No doubt Dog will also want a piece of the action!

Bill
This is what I was thinking although the Raymarine might not accept NMEA input from another device since I think it's equipped with its own receiver correct?

I think the actual question was whether the Raymarine and the Garmin can share the same antenna. I can't speak for the specific devices but my answer would probably be no or at least not out of the box. In order for 2 devices to use the same antenna you would have to isolate them from each other using some sort of duplexor. Whether one exists for this application, I don't know. Now if you want to use the Raymarine INSTEAD of the Garmin then you might be able to find an adapter for the antenna connections.
 

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Again, I’m posting from work so I don’t have all my technical notes before me so I can’t get into specifics, but here goes. I also was faced with a similar situation as you and was able to make it work with a single GPS. The Raymarine E system allows for either a Raymarine protocol “talker” (in this case the GPS) or one that uses NMEA protocol. The difference is Raymarine puts an extra letter (“R”?) in front of each message sentence that supposedly makes their network run better. You can hook the NMEA device into the proper connector in back of the “E” unit. The problem is the “E” unit processes the sentence and then puts the “R” in front of it, making it useless for any NMEA reading devices downstream (In my case my DSC radio). What I did to fix this was splice a junction block in the GPS cable before it connects to the “E” unit and run a cable from the junction to the NMEA reading device. You may need a multiplexer (highly unlikely) if the junction block solution doesn’t work. You can “bench test’ all of this on your boat before you start drilling and cutting cable.

I did this a couple of years ago on Freya and it took a little bit to all the devices to talk to each other – Just wait until you add an AIS unit to the mix! The good news is your oldest is just the right size for pulling cable. I was lucky, I used my nephew right before he had a major growth spurt. Now, I have to look around for another “little guy”. I think that your GPS mounting is perfect where it is and I see no reason to mount another (you can use a handheld unit as a back-up on your ocean trip.) Good luck on your installation.

One other thing. The coating Raymarine uses on their display screen isn’t very durable, making it subject to marring and scratching. There is a company that makes protective film coverings for palm Pilots and such that makes one for the E system. I highly recommend it. (I have that name down at the boat so I won’t be able to tell you before next week.)<O:p</O:p
 

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Discussion Starter #8
THANK YOU...

Damn...you guys made my head spin...what the hell are you talking about???

In a boat I can only sail...are you nuts??? I don't even know half thje stuff you guys talk about..

I m calling Cam on the phone...I am more confused than before...

sorry..my fault not yours
 

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One other thing. The coating Raymarine uses on their display screen isn’t very durable, making it subject to marring and scratching. There is a company that makes protective film coverings for palm Pilots and such that makes one for the E system. I highly recommend it. (I have that name down at the boat so I won’t be able to tell you before next week.)<O:p</O:p
I am interested in hearing about that, George. My outside unit has a scratch on the screen. I quickly learned to be very careful cleaning it.

Brian
 

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THANK YOU...

Damn...you guys made my head spin...what the hell are you talking about???

In a boat I can only sail...are you nuts??? I don't even know half thje stuff you guys talk about..

I m calling Cam on the phone...I am more confused than before...

sorry..my fault not yours
Ok I'll rephrase. I'll make sure to use small words for you :)

take the garmin thingy and get a wire to hook it to the raymarine thingy so they can talk and be friends. If they get along the garmin thingy till tell the raymarine thingy where the boat is and the raymarine thingy will show you. Just be nice to the raymarine thingy..
 

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You can split a NMEA0183 output signal and have it read by up to 4 listeners using a simple junction box. Anything past that you need an actual black box that splits it properly.

Garmin -> junction box -> other devices

Boy that connector on the back of the 185 is a goofy thing. Why couldn't they just put dedicated connectors on the back? One for NMEA, one to the transducer, one for power.
 

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You can split a NMEA0183 output signal and have it read by up to 4 listeners using a simple junction box. Anything past that you need an actual black box that splits it properly.

Garmin -> junction box -> other devices

Boy that connector on the back of the 185 is a goofy thing. Why couldn't they just put dedicated connectors on the back? One for NMEA, one to the transducer, one for power.
Or use something standard like, oh I don't know, RS-232
 

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Discussion Starter #13
OK...this is driving me nuts!!!!!!!!!!!!!!!!!!!!!!!

I called Garmin, and the girl there wasn't or sounded very knowleagable (SP??)

She said I could not split the wire from the Garmin antenna and feed it to the Raymarine. But she also said she wasn't sure..

The Raymarine guy (and Cam) said I could, just cut the antenna wire from the antenna to the Garmin, put new terminals or whatever they are called, split it, and put new wires to the raymarine.

Feeding a wire, from the back of the garmin GPS at the nav station, to the raymarine at the stbd wheel is a nightmare, too far and too many panels to remove...weight of the wire too.

Installing a GPS antenna in the radar pole is bad, becaus the pole may come off most of the time

Installing a GPS antenna on the push pit looks ugly, and is a risk of snag, plus need to make a hole to pass the cable.

Installing the GPS antenna in the deck, flush, means another great big hole on the deck...

What shall I do???

HELP!!!!!!!!!!!!
 

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Regarding splitting the antenna wire, wouldn't it better to have the systems separate as much as possible? If you go the antenna splitter, then if that one antenna fails, both GPSs fail.

I have a (small) GPS antenna mounted on the push pit that does the job well.

Food for thought -- why not mount the GPS antenna below the deck (up against the ceiling)? The GPS signals go through fiberglass, right?
 

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OK...this is driving me nuts!!!!!!!!!!!!!!!!!!!!!!!

I called Garmin, and the girl there wasn't or sounded very knowleagable (SP??)
The Raymarine guy (and Cam) said I could, just cut the antenna wire from the antenna to the Garmin, put new terminals or whatever they are called, split it, and put new wires to the raymarine.
Be careful with this option. It might work but I suspect you'll end up dropping the sensitivity of both units (more likely to lose GPS lock or take longer to get a lock). Not saying it won't work, just might have some adverse effects. I think the best method is to do what George and others have said. Split the NMEA signal.

As for Bene's comment, I suggest you look into a portable antenna to use incase the main antenna dies.
 

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Demystifying Networks

Giu, I think that everybody you talked to is a little bit right. First, how is your Garmin set up? Do you have a GPS display at the Nav station and the GPS antenna is directly linked to it? (please say yes). Then what you do is run a four wire data cable from the display at the Nav station to the NMEA connector on the E-System. The antenna cable is just an RF shielded cable and is not part of your “network” and therefore you can’t split the signal on the antenna cable. What got guys like me lost is Raymarine builds their entire GPS unit inside their antenna housing for guys like me who use their networked displays (E-system in my case). And when I say pictures of your boat I assumed you had the same thing. Now of course, if you want some on-site consultation, please send an airline ticket to… All of our talk about junction boxes etc. is if you want to split the GPS data between a non Raymarine DSC radio and the E unit. If all you want to do is have your GPS “talk” to the E-system then the single data cable is fine.

Have you talked to anybody on how you will disconnect the Radar cable at the boat side when you remove the radar pole? I’d love to hear your thoughts on this.<O:p
 

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Discussion Starter #17
OK...we have a winner..

after discussing with Cam (thank you G.), and with Raymarine, and you guys (thank you all), I was advised to install the second antenna. The RS125. They claim a pinpoint of 3 meters or less. Also have a redundancy. So this is the solution.

BUT what made me chose this was this here bellow.

The Raymarine antenna is divided in two parts, and I can have just the top mounted on the deck (they provide a dedicated gasket), and a small 1/4 in hole on the deck for it!!!!

Which I can deal with..With this system, the antenna will be only 6 feet away from the radar screen..

The downside of it..$300.00 for the antenna, but I can live with it.

THANK you guys!!!

Thank you!!!!

I owe you guys one!!
Alex
 

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Hmmm....$300 is just about the price of an airline ticket plus the $ .49 worth of wire it would have taken to solve the problem.

But, then, redundancy isn't a bad thing at all :)

Bill
 

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Alex-
As the doctors are told, "first do no harm". I think part of the confusion is that you are trying to deal with YnGlitch (technical jargon allegedly spoken in English, usually by folks with no skills in either) and there is mass confusion over what is or isn't an 'antenna'.

There are many "hockey puck" GPSes, which a little plastic lump about the size of a hockey puck or a mouse is actually a complete GPS unit, including the antenna and the circuitry to send data out on an NMEA or other line.

But these look pretty much identical to "active antennas", which are usually a mushroom-shaped GPS Antenna --and only an antenna-- connected by a coaxial cable to the rest of a GPS unit. A lot of people have no idea which unit is which, and you really have to check the printed spec sheet for the model number to be CERTAIN.

If the Raymarine radar has a provision for a GPS *antenna* I would be very surprised, since antennas tend to be matched to specific model GPSes for electrical signal, voltage, power levels. The odds are that the Raymarine has a provision for "GPS input" meaning an NMEA-level input form a GPS unit, and not from a GPS antenna.

"NMEA" is very similar to "RS-232" which was the standard serial connection for computer printers, mice, GPSes, etc. for many years. For sailors, they are almost identical and often are treated as identical.

Assuming your GPS unit has an "NMEA out" or "serial out" or "RS-232 out" port on it, those are all very similatr and any one of them can be connected to the "GPS in" port on the Raymarine. (Which might also say "NMEA in" or "GPS output" depending on who wrote the manual. An "input" and an "output" often confusingly are the same, just depending on which end of the same connection you are referring to.)

So, check your printed specs. If the Raymarine takes an NMEA signal from the GPS, you want to connect the NMEA output from the GPS, to the input on the Raymarine. That's an easy wire run. If your GPS already connects to an autopilot--that's probably the same wire and yes, it usually is OK to just make a "T" in the line and connect the one wire to all three devices.

Cutting into a GPS antenna cable, on the other hand, is not such a good idea. Coaxial cables need special fittings and tools, and the simple act of cutting the cable changes how it will carry signals "forever", no matter how well it is spliced or repaired. That can degrade performance, and if the Raymarine really has a connection for a GPS antenna--I'd be surprised, but then I'd say to install a second antenna, right on top of the radome and just for it, redundantly.
 

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Discussion Starter #20
Have you talked to anybody on how you will disconnect the Radar cable at the boat side when you remove the radar pole? I’d love to hear your thoughts on this.<O:p
George, thank you.

I have to buy these plugs (male female rubber connectors), that will allow that.

Basically when I disconnect the wire, inside the boat, the whole wire comes off with this plug.

Then the hole where the wire comes thru the hull is plugged with another plug I need to aquire. The hole is built into the hinged radar base, which is water proof.

Now, yes, the Garmin antenna goes only and straight to the Garmin.

Passin wires from the Garmin, inside the nav station, on port side, means remova all ceilings, on both aft cabins, and...I don't even put this option...

I go for the flush Raymarine antenna..simple, easy and clean.
 
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