ICOM M 802 SSB Install Part 2: GPS connection

[muttskie]

Ahoy,

I didn't want to drift the previous thread ( http://www.cruisersforum.com/forums/...es-160168.html ) from the discussed subjects, so this is a new thread about options for connecting the GPS data to a M-802.

There is an older thread that discusses NMEA0183 connections, etc., but it is very confusing to this NMEA2000 person.

And, the GPS input on the receiver uses a BNC connection.

Is there a simple plug and play GPS antenna that will function properly?
Something like this? If so, how is it powered?

Active external GPS Antenna for Garmin GPSMap 640 546 545 541 540 536 535 531 526 525 441 440 431 421 420 498 496 495 492 478 378 376 Streetpilot III, GPS II/III/V (comparable to Garmin GA 26C remote antenna, part #010-10052-04)

What is recommended?

Thank you,
Bill

[wrwakefield]

Originally Posted by muttskie

Ahoy,

I didn't want to drift the previous thread ( http://www.cruisersforum.com/forums/...es-160168.html ) from the discussed subjects, so this is a new thread about options for connecting the GPS data to a M-802.

There is an older thread that discusses NMEA0183 connections, etc., but it is very confusing to this NMEA2000 person.

And, the GPS input on the receiver uses a BNC connection.

Is there a simple plug and play GPS antenna that will function properly?
Something like this? If so, how is it powered?

Active external GPS Antenna for Garmin GPSMap 640 546 545 541 540 536 535 531 526 525 441 440 431 421 420 498 496 495 492 478 378 376 Streetpilot III, GPS II/III/V (comparable to Garmin GA 26C remote antenna, part #010-10052-04)

What is recommended?

Thank you,
Bill

Bill,

I used this pre-made cable (with ferrite) from Dockside Radio. [Cable is about half way down the linked page...]

Only from DockSide Radio

GPS Data Cable Kit
GPSK-802
The GPS-802 Data Cable solves the problem of getting GPS data into your M802. Simply cut the 12-foot cable to the length you need, connect the cable's center conductor to the GPS data out, the shield to GPS signal ground, snap-on the FairRite and you're "good-to-go".

The GPSK-802 consists of twelve feet of RG-174 mini-coax with a factory-installed BNC connector that fits your M802 on one end, & bare wire for connecting to the GPS on other end, one snap-on Type-31 FairRite, & an instruction sheet.

US$24.95* + Shipping**

I know we can also make these up ourselves, but I was ordering the DSC antenna anyway and felt lazy at the time.

Now you just need the answer to the other half of your question: where to tap the GPS input...

In case this helps...

Cheers!

Bill

[Paul L]

Do you already have a nmea0183 GPS input to your VHF? If so you can share it.

[muttskie]

Originally Posted by Paul L

Do you already have a nmea0183 GPS input to your VHF? If so you can share it.

My VHF is NMEA2000 and gets GPS data from the many GPS sensors (3 individual sensors, and the various ones built into MFDs, Vesper AIS, etc. ) on the N2K backbone.

It is an ICOM M506 AIS, and after checking the specs right now, it can output GPS data via NMEA0183!

So, I guess I have some NMEA0183 wiring to do!! Something I swore I would never do...

I guess I can make up a cable like Bill has described above. I have the technology!

[Paul L]

Yep, just take it as output from the 506. The 802 is picky on what position sentence it needs, if I remember correctly you need the GGA sentence for the 802.

[ka4wja]

Bill,
You've gotten the answers you needed....so, not much to add here....but...


But, for more than a decade I have personally recommended a separate, dedicated GPS receiver feeding DSC radios!
(although having a GPS receiver built-in to the radios would also be nice....but not available on an HF-DSC rig, yet...)

In addition to solving the NMEA0183 issues, position sentence issues, etc., this allows your DSC radios (which are part of the GMDSS, and an integral part of a cruiser's on-board distress signaling system) to always have current GPS position data, no matter the status of any other system on-board!!

I have seen way too many systems set-up with NO GPS data sent to the DSC radios, and still many set-ups that have the damn chartplotter NMEA output driving the DSC radios!!
(Like everyone always has their chartplotter up and running 24/7?)



Taking NMEA 0183 output from your VHF is okay, but then the question comes back to how is the VHF getting its position data (NMEA 2000 network???)
Also, taking your Vesper's NMEA output is also possible...but, again this makes your DSC position data dependent on another "system"...


I know in 2016, it sounds like I'm recommending a big step backwards to set-up a dedicated GPS, feeding NMEA 0183 to your DSC radios....and I know that this technically is another thing that could fail, but in my opinion this is the best over all approach...

And, also with the cost of a Gamin handheld, etc. being so cheap, having a few on-board is always nice (I have THREE of them, 2 newer GPS MAP 76cs and one GPS76)....and having a set-up where one of them is always ON, sending NMEA0183 data to the radios, is a cinch!!


Here is what I have been using for about 12 years now:












fair winds..

John

[muttskie]

Originally Posted by ka4wja

And, also with the cost of a Gamin handheld, etc. being so cheap, having a few on-board is always nice (I have THREE of them, 2 newer GPS MAP 76cs and one GPS76)....and having a set-up where one of them is always ON, sending NMEA0183 data to the radios, is a cinch!!
fair winds..
John

Thanks, John.

I actually would prefer this method. I could stash the GPS receiver/handheld in the same cabinet that the receiver is in and, if needed, pull it out ( still connected, of course ) and have it available without the need for any other electronics to be on.

Good idea.

Bill

[Paul L]

Originally Posted by muttskie

Thanks, John.

I actually would prefer this method. I could stash the GPS receiver/handheld in the same cabinet that the receiver is in and, if needed, pull it out ( still connected, of course ) and have it available without the need for any other electronics to be on.

Good idea.

Bill

You want to hide the GPS inside a cabinet? Not a great place for satellite reception.

[muttskie]

Paul,

I thought about that, too, but the cabinet is a very short distance below the cabin ceiling. I have an older Garmin handheld that I keep in there that has no trouble keeping a fix. And, there is no significant metal structure in the vicinity, other than the boom approximately 4-5 feet above. All of my GPS sensors are below deck mounted. All of them work perfectly.

Bill

[Paul L]

Originally Posted by muttskie

Paul,

I thought about that, too, but the cabinet is a very short distance below the cabin ceiling. I have an older Garmin handheld that I keep in there that has no trouble keeping a fix. And, there is no significant metal structure in the vicinity, other than the boom approximately 4-5 feet above. All of my GPS sensors are below deck mounted. All of them work perfectly.

Bill

Just a couple of comments. GPS antennas that work great at 38*N may not be as strong in a different area, like at 40*S.
I'd look at your system and see what systems are normally going to be left on and can deliver the nmea data you need. If there aren',t any then adding the extra GPS and wiring it in is fine. I'd also have a spare GPS not wired in and in the oven for lightening protection. In my case I use the ais transceiver output for my shared GPS nmea data. It is left on at anchor as it feeds the anchor alarm, vhf and ssb radios. It is low current draw and doesn't need the chartplotter to be on.

[muttskie]

Originally Posted by Paul L

Just a couple of comments. GPS antennas that work great at 38*N may not be as strong in a different area, like at 40*S.
I'd look at your system and see what systems are normally going to be left on and can deliver the nmea data you need. If there aren',t any then adding the extra GPS and wiring it in is fine. I'd also have a spare GPS not wired in and in the oven for lightening protection. In my case I use the ais transceiver output for my shared GPS nmea data. It is left on at anchor as it feeds the anchor alarm, vhf and ssb radios. It is low current draw and doesn't need the chartplotter to be on.

Thanks, Paul.

Good comments and ideas. I do have a Vesper Vision on a separate breaker, as are the VHF and SSB. Without too much work, I could do the same as you have described, in addition to having a dedicated GPS ready. After all, it is a BNC connection to the SSB. Easy to switch in seconds.

Thanks,

Bill

[ka4wja]

Hang on a second, Bill...
For such an easy subject, this discussion is getting pretty deep into the weeds....
Just make it simple, and don't worry about all the BS...


Two important points to clarify...


1) Not sure if I understand your set-up....but be aware that just because the M-802's NMEA input uses a BNC connector (for NMEA 0183 position data input), this is NOT the same as an AIS transponder's GPS input / BNC connector!!!

Originally Posted by muttskie

I do have a Vesper Vision on a separate breaker, as are the VHF and SSB. Without too much work, I could do the same as you have described, in addition to having a dedicated GPS ready. After all, it is a BNC connection to the SSB. Easy to switch in seconds.

The M-802, like just about all other consumer marine electronics these days, uses NMEA data (NMEA 1083, in the case of the M-802), but your AIS transponder has a GPS receiver built-in to it, and it's "GPS input" is NOT NMEA data, but is the external GPS antenna connection!!!

AIS transponders require (under int'l law/agreement) their own, direct GPS position fixing receiver, and as such have this built-in....and the GPS antenna is just that an "antenna"....
But, what is used by almost all other consumer marine electronics, what most everyone thinks of a GPS antenna, is actually the entire GPS receiver built-into the antenna, and NMEA data (or SeaTalk data) is what comes out of it...

So, be aware that you cannot just plug your Vesper's ext. GPS antenna into the M-802's BNC connector / GPS input....it will NOT work!!
The M-802 requires NMEA 0183 position data (GAA, I think), which you could certainly get from the Vesper Vision, but NOT from the GPS antenna...


I realize this seems complicated, sorry about that...
But, here again is where just using a separate, dedicated GPS receiver for NMEA input to the DSC radios makes things easy-peasy!



2) Make sure you have the "power/data" cable (about $12 - $15), and preferably also a secure mounting arrangement for the separate, dedicated GPS receiver....
Otherwise you're just adding lots of unreliability as well as more complexity to your system, rather than less!



I hope this helps...

fair winds..

John

[Paul L]

John
I'm pretty sure he knows he can't use the BNC on a GPS unit. Many AIS units can have a low speed (4800 bsud) 0183 output enabled that passes the position sentences, not the AIS sentences, such as the em-trak units.

[SoonerSailor]

I use an old Garmin GPSMap 60 handheld. It is in a RAM mount in a visible corner of the nav station and I feed it 12V power from ship supply. Its NMEA output feeds the M802 and VHF, also goes to a MUX which uses its data as backup to the netbook and chartplotter if primary gps fails. Its also sometimes the only GPS running on a long passage when other electronics are shut down to save power.

It reliably feeds all three devices which are in parallel to the little Garmin's NMEA output.

This has worked well for me.


Sent from my iPhone using Cruisers Sailing Forum

[muttskie]

Thank you all for your helpful comments.

I have purchased the Dockside Radio GPS data cable and will connect it to the Vesper Vision's NMEA0183 GPS data output.

The Vesper specs are very clear about it's ability to output, via NMEA0183, NMEA2000, WiFi, and USB, GPS position data. As I am allergic to NMEA0183, it will be my ability to figure out the proper connections that will be the weak link.

I would normally have the Vesper Vision on all of the time and it has it's own dedicated Vesper external antenna, so I wouldn't rely on the other GPS receivers on my NMEA 2000 network for position data. The Vision always displays position data, regardless of the mode it's in.

Also, I might include the ICOM 506 VHF into the Vision's NMEA0183 GPS connection. This would negate the need for powering up the NMEA2000 network to provide the VHF with position data.

If this doesn't work ( though I don't see how it couldn't ), I'll buy another Garmin handheld.

Bill