VHF with AIS, any recommendations??

[buzzstar]

I do not really wish to change the OP's question, but are there any "nays" re the brands mentioned, and if so, why?

[01kiwijohn]

I'm with O'Reilly on this. My SH (now Yaesu) has been great. Two years of Pacific NW cruising, in the occasional fog. One N Pacific crossing.
The CPA alarm works really great, and we did use the DSC to contact a couple of ships where our CPA was going to be close. We just called to make sure they'd seen us on radar (they had) and whether they planned to change course (they did). Bonus; also got a good weather report.

[toddster8]

Originally Posted by Mike OReilly

It was toddster8, post #7: http://www.cruisersforum.com/forums/...ml#post2340118

I should have known better than to try to paraphrase something that I didn't fully remember. Lets see if I can copy the discussion from a PDF of another device manual, below. The Standard Horizon would be the "single-ended" signal in the discussion, with only a common ground signal for both high speed and low speed ports.


QUOTE:
Although the NMEA 0183 standard specifies the signal names, voltage levels and connection methods very clearly, the reality is far from this ideal world.
The most important property of an NMEA port is that the connections or wires are labelled A and B and that it uses a differential signalling scheme. This means that data is transmitted on both wires, but in “opposite direction”. Both wires are driven between 5V and 0V and opposite of each other. This means when wire A is at 5V, then wire B is at 0V and when wire A is at 0V, then wire B is at 5V. The advantage of this signalling scheme is that it is very insensitive to electrical interference.
NMEA A and B are often labelled as NMEA + and - respectively. When connecting devices, simply connect NMEA A to NMEA A or NMEA + and NMEA B to NMEA B or NMEA -.
Things get complicated when manufacturers don’t follow the NMEA 0183 standard, which is very often the case. Many devices have an NMEA interface, which is actually an RS-232 interface. The only resemblance with the NMEA standard is the format of the data transmitted. Electrically, they are an entirely different world. The used signal names differ wildly and often lead to confusion. When a device has a NMEA input with connections “Data In” and “Data Return” it is often not clear whether this input is galvanically isolated or if “Data Return” is simply another name for “Signal ground”.
Instead of being fully compatible with the NMEA standard, many devices use a single-ended signalling scheme where data is transmitted on one signal wire while the power ground presents the return path for data. Single ended devices often have connection names like TX and Gnd (transmit and ground) on the NMEA output and RX and Gnd (receive and ground) on the NMEA input. Also used are Data Out, Data In and Signal Ground. Mix these with standard NMEA connections and confusion is imminent!
In general it is easy and safe to connect a single-ended output to a differential input. How to connect a differential output to a single ended input however is less obvious. When NMEA B of an output is connected to the signal ground of an input, the B signal is actually short-circuited to ground. A properly designed output can handle this abuse but it will result in fairly high currents in cables, which in turn can lead to severe interference on SSB and VHF radios In the worst case, the output will be damaged.
END QUOTE

(Also, another issue is that, the SH GX2000 almost never displays vessel names and other "fixed" data. It just lists contacts by their MMSI number. It can do so, because names have popped up once or twice, briefly, in the last four or five years. Generally to see the vessel name I have to pop down the nav station and read it from the laptop. If the laptop happens to be running.)

[continuouswave]

Originally Posted by toddster8

I should have known better...

[long quoted text omitted]

I agree.

The GX2000 user manual is available from:

http://www.standardhorizon.com/downl...pplication/pdf

The GX2000 user manual clearly shows that the NMEA-0183 interface is provided on two conductors, and is not single ended. I think you are trying to assert that the NMEA-0183 on the GX2000 is something other than what it actually is.

[toddster8]

Originally Posted by continuouswave

I agree. You should have "know better", by which I mean you were being a bit "lazy" in your research before you decided that there was a defect in the NMEA-0183 interface on the GX2000 radio.

The user manual is available from:

http://www.standardhorizon.com/downl...pplication/pdf

It clearly shows that the NMEA-0183 interface is provided on two conductors, and is not single ended. I thnk you are trying to assert that the NMEA-0183 on the GX2000 is something other than what it actually is.

Thank you for the link to the new manual. It does appear that they have fixed the interface on newer units of this model. It makes me wonder what else they may have changed?

I assure you that the hours I have spent trying to mate this radio up with other NMEA 0183 equipment doesn't feel lazy. I suppose the only relevance to the OP would be, "take care if buying older units from eBay or the like."

[continuouswave]

Originally Posted by toddster8

Also...the SH GX2000 almost never displays vessel names and other "fixed" data. It just lists contacts by their MMSI number. It can do so, because names have popped up once or twice, briefly, in the last four or five years. Generally to see the vessel name I have to pop down the nav station and read it from the laptop. If the laptop happens to be running.)

A vessel sending AIS transmissions only sends its VESSEL NAME every six minutes. If your receiver happens to miss that one transmission that occurs only every six minutes, the vessel name might not show up for 18 minutes or more. Or the vessel could move away and out of radio range before your AIS receiver can pick up the vessel name.

How the GX2000 displays AIS targets on its small display is not a function of its NMEA-0183 interface.

Your laptop is probably running some sort of chart plotter application. Perhaps the chart plotter application maintains a large cache of data about MMSI numbers and vessel names. That is a reasonable thing for a chart plotter to do.

The GX2000 is not a chart plotter; it is a radio with a small LCD display that provides a very limited mini-chart plotter function to show targets.

I don't think it is a fair comparison to complain that a radio's mini-chart plotter does not provide all the features of a chart plotter; if that were a reasonable argument, one could then equally complain that the laptop chart plotter is a "lazy" implementation of a radio.

[continuouswave]

Thanks for the image of an old manual page. I have never seen that before. Your comment about single-ended appear to be applicable to some legacy model of the GX2000 that predates what was later offered. And, I agree, single-ended interfaces are a bit of a nuisance.

I realize now that were was some confusion on both our parts about the nature of the NMEA-0183 interface, and apparently it changed during the manufacturing of the radio. My apologies for not being aware of that earlier version.

By the way, conformance to NMEA-0183 signal standards has gotten much better in radios made in the past few years. Many are now using standard wire color codes and providing balanced signals. But the makers still seem reluctant to use the standard names of TALKER A/B and LISTENER A/B. They keep giving polarity indications to the signals, which are really not appropriate.

ASIDE: I have put some effort into designing a universal wiring method to connect NMEA-0183 devices. It uses a five-pole connector. All devices are wired the same way. I have wired all sorts of NMEA-0183 devices with this method, and they all interconnect perfectly. Of course, the baud rate must be the same. I describe the method, if you are interested, at

NMEA-0183 INTERFACE DATA COLLECTION
NMEA-0183 Interface Data Collection - CONTINUOUSWAVE

I have also collected a fair amount of data about many radios and chart plotters, and describe how to use the method to interconnect them.

I also show a more elaborate interconnection in another article, using a backplane or daughter board to make the interconnections. See

http://continuouswave.com/whaler/ref...lNMEA0183.html

I have invested some time and thinking about NMEA-0183, and I have developed a very simple and easy to use method to interconnect devices. So it's not a problem for me to accomplish this, but I realize for many boaters who are not particularly devoted to serial data communication, NMEA-0183 is not a simple process.

[mitiempo]

Originally Posted by S/V Alchemy

I installed a GX-2200 last year and even on AIS......

A point of interest is that I just purchased a Standard Horizon VHF handheld, the HX 870. This unit has a USB data cable and internal GPS; I believe I can plug it directly into a computer running OpenCPN and receive AIS targets, which addresses your NMEA observation. My blog post is here: The world encompassed: Handy dandy

The HX 870 does not have AIS.

[gazzas_uk]

Originally Posted by Mike OReilly

The SH 2200 has served me well these past few years. Radio is great, and AIS receiver works fine. GPS picks up from inside the cabin with no external antenna needed (although sometimes it takes a few extra minutes to get a position, resulting in an alarm). With the RAM I can have the data and basic display in the cockpit, and the NMEA 183 link lets me mirror it on my Garmin chart plotter.

+1

Have had the SH 2200 for 2 years and its great, especially with the Ram mike extension which gives you the basic AIS information at hand in the cockpit, and yes it does give you the vessels name and other information...I would highly recommend it ...the "new" model just released is a transponder unit and looks very nice....but with a heavy price tag to go with it !!

[mrm]

Originally Posted by continuouswave

[...]Although NMEA-2000 might be 16 or 17 years old, it has begun to appear on VHF Marine Band radios only in the last year or two.[...]

I think it is already 8 years since we have had a Garmin VHF 300i AIS installed, and IIRC it was on the market for a while. Not debating other points you made, but just to say that N2K appeared in marine VHF a bit earlier.

[continuouswave]

Originally Posted by mrm

I think it is already 8 years since we have had a Garmin VHF 300i AIS installed, and IIRC it was on the market for a while. Not debating other points you made, but just to say that N2K appeared in marine VHF a bit earlier.

Thanks for that data on the epoch for NMEA-2000 interface in a VHF Marine Band radio being c.2009 and being accomplished by GARMIN. I did not realize the GARMIN VHF 300i had been around for that long. Its rather hefty price ($1,000) probably caused me to not pay close attention to it.

I think the less expensive GARMIN 200 radio ($400) also has NMEA-2000, and (based on some blog site archives) it appears to have come on the market around August 2009--tempus fugit.

I did a bit of research and found some comments about these early versions of Garmin radios with NMEA-2000. The comments reinforce my earlier remarks about buying the first-generation of radio products with NMEA-2000.

Cf: http://www.panbo.com/archives/2009/0...pressions.html

Pull quote:

This VHF has been one of the biggest failure products Garmin ever produced. I won’t get into all the problems I’ve had, but will say my radio has been back to Garmin for repair under warranty three times.

[Sandero]

Another vote the the Standard Horizon... excellent. Lot's of good stuff packed into this baby.