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NMEA183 connection between Garmin GPS and Uniden VHF


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My trusty old VHF has died so I have replaced it with a Uniden UM380. I also have Garmin 421 GPSMAP and reading the handbooks it appears in can create a NMEA 183 connection between the two so the VHF gets the GPS data an can transmit it in a distress situation etc.

 

The Garmin manual says; Black ground to NMEA ground on the device and Blue( out) to NMEA Rx/A(+) on the device.

 

Uniden manual says; Bare wire to Ground on GPS, Green GPS data IN +

 

Sounds easy only two wires involved, so I have done this and no GPS data appears on the radio and after 30 mins it complains about no GPS data.

 

Should I have also connected the NMEA out as well on the radio to the GPS in ?

 

The GPS is configured for NMEA on serial port 1, standard, not high speed.

 

Anyone been in this dark space care to advise?

 

Thanks

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Hi eruptn, should not be to difficult to sort. If the connection is correct (and it sounds like it is), then I would suspect it is the NMEA sentences the GPS is producing are not the ones the radio expects. On my unit, a furuno, there are 3 possible sentence sets that can be sent to the radio. The radio only likes 1 of them. Check the manuals of both for abilities and or requirements.

Let us know how you get on - it is possible to connect a laptop to the GPS and see what's actually being sent, but that's really a little more complex, so we'll go there if we have to....

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Sometimes the manuals leave out the bit that although the units are "capable" of transmitting and receiving NMEA sentences, they hide the bit that "YOU" are required to go into the "SETUP" menus / options and turn "ON" the sentence to be transmitted or received. (Yes/No or tick box / radio button options).

 

This is after the units are powered up, of course.

 

Also some VHFs with DSC functions still need the MSMI number loaded BEFORE they will receive and NMEA sentence. Coastguard Boating Education Services at Westhaven allocate the MSMI numbers to VHF radios sets.

 

Hope that helps.

 

Google will find a lot of good info about NMEA sentences, structure and content.

Oh, there's so much to learn :crazy: :crazy: :crazy:

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Thanks for the comments. I've not found many places to deal withe the sentences , will keep looking.

The MSNI number may be signiificant, I've emailed Coastguard twice re this but they still haven't replied after 10 days.

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My trusty old VHF has died so I have replaced it with a Uniden UM380. I also have Garmin 421 GPSMAP and reading the handbooks it appears in can create a NMEA 183 connection between the two so the VHF gets the GPS data an can transmit it in a distress situation etc.

 

are you aware that this function is not officially monitored in NZ?

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Grant, that does not mean you should not use it, it just means the authorities don't monitor it. Many commercial vessels, as well as offshore yachts have it connected. There are an awful lot of vhf sets in use in NZ that will hear a dsc distress signal, including mine...

I certainly would NOT rely on it primarily though....

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Grant, that does not mean you should not use it, it just means the authorities don't monitor it. Many commercial vessels, as well as offshore yachts have it connected. There are an awful lot of vhf sets in use in NZ that will hear a dsc distress signal, including mine...

I certainly would NOT rely on it primarily though....

 

IT, yes agreed, if it turns bad any option is good, just pointing out that it not guaranteed to be heard or responded to

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See "Solution 1" at the bottom of the page. Just did this last year.

 

http://www.kiwiboatowner.com/2013/07/el ... oject.html

 

Your GPS antenna will be transmitting NMEA 0183 sentences to your chartplotter. Intercepting these sentences at a junction box (terminal strip) is as easy as splicing a couple of wires once you find which one has the signal.

 

Because NMEA signals are so fast, a multimeter won't help, so if you don't have a manual that tells you, you will need an electronic specialist with a meter that can detect the signal.

 

You simply intercept this signal and split it, one to your chartplotter and one to your VHF (get an appropriate pin for the VHF plug). Where to stick it in the VHF? Again, a manual is required, you are looking for NMEA IN.

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John, not so easy - I'm pretty sure he has the connection, that's why it says "no GPS data" The data it's receiving is not what the VHF expects, so it's either Garmin specific data, or the wrong NMEA sentences.It's a pretty easy process to connect the GPS output to a PC serial port and read what is actually coming out... The problem is very likely config of the GPS unit.

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Garmin has only ever produced NMEA 0183 and NMEA 2000 data-producing equipment. Raymarine used "Seatalk" at one point, but not Garmin. It stands to reason then that the Garmin and uniden are entirely compatible. Garmin units transmit all the sentences beginning with PGR...that the Uniden should understand.

 

The blue wire from the Garmin connects to the yellow wire on the Uniden, and the black (earth) from the Garmin connects to the bare wire on the Uniden. The Uniden UM380 manual clearly states that NMEA IN (+) is yellow, not green (which is NMEA IN (-)). If this doesn't work, the Garmin isn't transmitting.

 

Use the yellow wire and report back. You have to understand that there is an NMEA IN + and - Use the NMEA In +....which is yellow. :thumbup:

 

 

http://www.uniden.com/content/ebiz/uniden/resources/ownersmanuals/UM380om.pdf

 

PAGE #29

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BTW, did you know that after you solve this minor hiccup, you can also connect a few more wires that means that if anyone else out there (like me) is using the GPS-VHF set-up, when I call you my position will show up on your chartplotter?

 

Brown (NMEA OUT -) to NMEA IN- on chartplotter

White (NMEA OUT +) to NMEA IN + on charplotter.

 

Remember....NMEA IN has a + and -

NMEA OUT has a + and -

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John, that is somewhat misleading. Yes, garmin produce NMEA 0183 and NMEA 2000 devices, however, they also have Garmin - Garmin modes where they speak a proprietory language.

 

Here are the relevant extracts from the Garmin Manual;

Garmin GPS 400 Connection Setup.jpg

garmin GPS 400 Connection Setup Part 2.jpg

 

As you can see, there are three possible modes of output, Garmin Data transfer, NMEA standard, and NMEA high speed.

 

It appears that the NMEA standard (probably 4800) is only DPT,MTW,and VHW sentences.

More promising is Port 2, which has a configurable NMEA output where you can select the sentences required. I'll quickly check now what sentences the Radio requires....

 

If this part is not done correctly, there is no chance that a connection between will work, regardless of your wiring.

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OK, the radio supports RMC, GLL, GNS, GGA and ZDA sentences, as per the manual John provided the link to. SO, the standard sentences provided on port one of the GPS/Plotter won't work. Connect the cable to port two, as per the wiring instructions given, and select at LEAST RMC and GLL (but also GNS,GGA,ZDA if available, and you'll be away.

These two devices certainly can be connected and provide full functionality, incl DSC alerts displayed on the plotter, and the ability to make a DSC VHF call to a vessel displayed on the plotter (either by DSC position, OR AIS position.)

All Good.

Feel free to ask if you have any problems.

 

Matt

Neptune's Gear Ltd

Boating Equipment fit for the King!

http://www.neptunes-gear.com

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Here is an article here on what happens and more importantly what doesn't happen if you push the DSC button on your VHF. Based on this article it suggests all VHFs within the coverage area automatically turn to channel 16 and emit a warble sound. This may be an advantage if you follow up the distress with a Mayday.

 

http://baymarineelectronics.co.nz/latest_news/dsc/

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That article is pretty lightweight, and tells you what happens when a dsc distress message is received by a handheld. If it is received by the system this thread is about, or any other dsc capable and connected plotter, a distress icon will appear on the plotter at the location of the transmitter. Alarms will sound, the vhf, as mentioned, will switch to check 16. The big issue is the automated location of the distress on the plotter. Many plotters can do this, as can open cpn and many other PC apps, and some tablet/pH apps, if the right WiFi connections are made.

Its a pretty good system.

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I would appear to be in the presence of an actual expert I missed the proprietary Garmin language altogether. My mis-information was well-intended. :)

 

I hope at least I'm proven right about the yellow wire.

 

Going through this on my system was made easier by my B&G not having options for data transfer, just sentence selection.

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Thanks for all the conversation on this, some is making lots of sense. Now that I have finally escaped Wellington I'll be able to test this on the boat.

I have also received the MMSI number from Coastguard so will be able to test that option as well.

The port 2 info sounds very promising as I just went with port 1 in the first instance.

I understand the background to DSC not being supported, but if the handbook says they will talk to each other then I see a challenge.

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Interesting thread - I gave up on a Lowrance GPS-Raymarine VHF connection a couple of years ago but am watching with new hope :wink:

 

Always knew about the limitations of DSC but the value of having the position off the GPS (which is out in the cockpit) displayed on the VHF screen in the event of ever needing to make a distress call, seems to speak for itself.

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