VHF Radios

[ratherbefishing]

Hey all,
With the endless selection of VHF currently available on the market I am curious what others are using. Specifically, I am debating about the merits of a Class D vs 'regular' DSC equipped radios. Yes, I like the AIS enabled Standard Horizon but am not going to fork out the extra money for it (plus I can't link it to my current Lowr 527 plotter). I relaize I should stop squeaking and buck up the extra $50 for the Class D but...thoughts commments?
Cheers

 

[beemer]

Hey RBF , my experience is that if you are going to DSC other boats using their MMSI numbers you probably want a class D. If you are using your VHF for just basic communication etc you are probably ok without. My 2 bits. beemer

 

[Charlie]

You might want to take a look at the specifications of what you are getting ready to buy? All DSC and DSC Class “D” radios – are “NOT” created equal!

Unless things have changed in the last few years? An IEC class “D” which I have – will have a dedicated receiver that monitors channel 70. A normal DSC w/o Class D scans the channels. Many of the VHF/DSC radios have a single receiver that scans for calls on channel 70 along with all they other scanned channels. Reception of a signal on any other channel will prevent the radio from receiving a hailing call on 70… that would be your main difference! Both can have NMEA in and out and show on your plotter!

Class “D” radios that have the additional receiver is constantly tuned to channel 70 “generally” (see next paragraph). They do normally provide addition DSC functions. The Class "D" is defined differently in two separate international specifications, IEC 62238 and ITU-R M.493-10. The IEC specification requires that the radio be equipped with a watch-standing receiver for channel 70 that must always be available to receive calls—it cannot be used to scan or listen to signals on other channels. Virtually every country (other than the U.S.) requires Class "D" VHF/DSC radio comply with the IEC specification.

In the U.S., a radio can be identified as a Class "D" even if it complies “only” with the ITU specification. This specification spells out the types of DSC calls the radio must be able to transmit, but it does “not” require a dedicated channel 70 watch-standing receiver—a single receiver that scans channel 70 is sufficient.

So, if you do go with the Class "D" you might want to check on that, as I don’t know which is allowed in Canada?

IMHO the Class “D” is worth the additional cost!

 

[ratherbefishing]

Thanks fellas,
Every Class D I have seen here on VI has a separate Channel 70 receiver allowing constant monitoring of DSC calls while still allowing 'normal' VHF radio use. I've decided to go with the Class D for the extra $50 as I believe we'll see increased DSC use is the future and having a separate 'monitor' will only be a good thing. If I can afford a boat and all the gear that goes with IMO

 

[ratherbefishing]

Thank again guys. Any real world experience with Class D vs regular DSC?

A request tho please Charlie, I know you quote a lot of articles in your responses and I think we all appreciate your efforts but when doing so could you please reference the article? For example, the info you provided to my info request was almost verbatim from http://www.yachtingmagazine.com/article.jsp?ID=21014386 (which I had already reviewed). There is lots of good stuff other than that which you copied and I think the authors deserve credit.
Cheers

 

[searun]

Anyone had any success connecting two DSC radios to one GPS output? It may be my wiring prowess (rather lack of) but I can only get one radio to display GPS data. Any suggestions from those who are not electrically challenged like me! []

Searun

 

[Charlie]

quote:Originally posted by ratherbefishing

Thank again guys. Any real world experience with Class D vs regular DSC?

A request tho please Charlie, I know you quote a lot of articles in your responses and I think we all appreciate your efforts but when doing so could you please reference the article? For example, the info you provided to my info request was almost verbatim from http://www.yachtingmagazine.com/article.jsp?ID=21014386 (which I had already reviewed). There is lots of good stuff other than that which you copied and I think the authors deserve credit.
Cheers

rbf... I quote a "lot" from different articles and try “very hard” to give credit where credit is due and provide the references, especially on copyright material! That is why you will see all those “links” in my posts! Just for that reason! For reasons you do not know I am actually sensitive to that issue! I agree, one should get credit for their work! Some are just the proper thing to do - and depending on the circumstances, some are legally required!

The reference to the article you gave was actually a re-write and has been done so, many times. I am not sure “who” is/was the “original” author of that article, but I don’t believe it was they that you referred to? That particular article is a re-write from their own 2005 article, which “that” article was sourced from different articles. Much of it could have even come from Westmarine "West Advisors", which also has no author given. They all have and use the same terminology and wording! Also note there is "no" copyright on any – there is a reason for that! Since you mentioned it, as far as I can tell the original article was published in Boat/US magazine, September 2000 and Copyright 2000 Boat Owners Association & Gale Group. It appears all the rest are just rewrites and updates from there? So I believe, if any - that would be your correct credit?
http://findarticles.com/p/articles/mi_m0BQK/is_5_5/ai_65513074/
http://www.westmarine.com/webapp/wc...sor/10001/-1/10001/VHF-Fixed-Mount-Radios.htm

I will give "Chuck Husick" credit for being (and writing) a lot of things - he seems to have gotten around quite a bit? There are many articles published with his name; however, if he is/was the “original” author of any and Boat/US or BOA does not have a copyright, I would be surprised! Personally, I quit digging that deep. I know if it is commercially published and “not” copyrighted, the information has been taken from “public domain” or compiled from other sources. Just check the newspapers and see how many articles have a copyright?

Now with all that said… again, I am sensitive to work done by others and I actually do have copyrights. I agree whole-heartedly in giving credit where credit is due… Hope all this makes sense?


Now with that out of the way... "real world experience"?? Is that referring to me?? If so, I believe owning and operating VHF radios since 1977, might give me a little "real world experience"? Since in the past have owned DSC with Class "D" and currently own an ICOM-602 Class "D" I guess that would qualify me on both counts??

And may I say again... "you need to read the specifications"? If you think ITU isn't on VI and in Canada, you might want to check a little closer? And, unless something has changed I don't believe ITU is TC authorized on any "commerical" craft - but?? Here is a good example... how many ICOM-602 are in Canada? My ICOM-602 Class "D" clearly states, "Built-in DSC meets ITU Class D requirement"! Notice it does "NOT" say anything about "IEC"? Now if you really want, pull up the following owners manual, go to specifications, under receiver... it states "•Receive system : Double conversion superheterodyne". Look through the whole owners manual for anything referring to IEC... it isn't there! It does not list any dual receiver, nor say anything about dedicated to channel 70 in the specs. But if you go to page 34 you will see how it works!

As stated not all VHF DSC Class "D"... are created equal! I guess this could count for first hand "real world experience" with DSC and Class D, ITU, and IEC? Once more, know what you are buying! [:0][:0]

I will let you research what the "Double conversion superhetrodyne" is, that took me awhile!
http://www.icomamerica.com/en/downloads/DownloadDetails.aspx?Document=96

Oh... forgot! I wrote this, so no other credits required!
Cheers!

 

[Charlie]

quote:Originally posted by searun

Anyone had any success connecting two DSC radios to one GPS output? It may be my wiring prowess (rather lack of) but I can only get one radio to display GPS data. Any suggestions from those who are not electrically challenged like me! []

Searun

I have a GPS antenna going bad as we speak. It currently has enough signal strength to power the GPS display, but not the data on the radio. Are both displaying data when individually connected? If so, I would say your GPS signal is not strong enough to support the second radio? Wiring and connections good and clean? After that, I would be looking at VHF signal booster?

Sorry, I don't have any reference for this!

 

[searun]

Thanks Charlie...yes my old ICOM displays "GPS" on the display indicating it has a signal, but the brand new one will not. All new connections which has me wondering if I goofed up when doing the split. Back to the drawing board..I hate wiring...its kind of like trying to figure out what the hell your wife wants you to say when she asks.."does this dress make me look fat?" No matter what you do, you probably will screw it up!

Searun

 

[Charlie]

Searun, I hear ya about the wife!

If you are wiring another ICOM and wondering about connections, this link might help?
http://www.icomamerica.com/en/support/kb/Default.aspx

 

[GLG]

Searun I do not think you can split the signal coming from your GPS to 2 radios. The signal coming out of your GPS is basically RS232. One wire is TX (transmit), one is RX (receive) and one is Ground. This is a two-way communication system. That’s why you hook one device TX to the other device RX. The grounds tie together and this controls when data is sent between devices. (Buffer full - lift ground)
An analogy in the computer world would be Com1 and Com2 (9pin d-sub) on the back of your computer. In the old days we plugged a mouse in one and a modem in the other. 2 separate RS232 communication ports.
There maybe a device on the market that will accomplish what you are trying to do. I have not looked. Maybe there is another channel (com2) coming out of your GPS that you can tap into I do not know. Hope this helps you understand what is going on.

 

[Kisinana]

Searun
GLG has made a mistake. RS232 is just the type of plug (9 pin cable)used for interfacing to a computer or other equipment.
I would be more inclined to check your wiring. As you say your old system worked fine.
Most boaters have just one GPS unit and antenna tied to both their fishfinder and radios.

I have mine tied to my laptop for charts and position and my radio for DSC.

 

[GLG]

Kisinana I don't think I am wrong about the RS232. It's not the plug that maters. It could be 9 pin, 25 pin or bare wires. It matters not. It is an engineering specification. (http://en.wikipedia.org/wiki/RS-232 )

If you look at the post Charlie provided (thanks) on another thread it has a link to a PDF from Lowrance.
http://www.lowrance.com/upload/Lowr.../LMS480-cable-connect-dwg_0154-181_050504.pdf

Look on the right hand side and you will see the cable is marked as a NMEA 0183 Data Cable. RS-232 COMM
http://en.wikipedia.org/wiki/RS-232#Related_standards


I was trying to explain how it works. Maybe a little too confusing. Here is a link on how to use it in a 3 wire setup like on the Lowrance ( http://en.wikipedia.org/wiki/RS-232#3-wire_and_5-wire_RS-232 )

My whole point is .. I don't think you can splice the wires together and get it to work.

Searun try this. Turn on your GPS and radio 1. Does it work? Turn off that radio and turn on radio 2. Does that work. Note make sure all your equipment is set at the same Baud rate. You don't need high speed, as there is not much data being passed between devices.
This should work unless you have some wires crossed.

Hope I have not confused too many out there, It is not easy to explain.
GLG


Kisinana how do you have your laptop, GPS and Radio hooked up all at once. Are you using USB and RS-232?

GLG

 

[GLG]

For those geeks out there here is a link in regards to the other communications that are on the modern FF, GPS, Radar, Radio
http://en.wikipedia.org/wiki/NMEA_2000

Personally I think there is a ton of room for improvement in the hardware.

 

[Charlie]

GLC… I believe what you are stating is correct, but I beleive we would be dealing with RCA plugs here? I also, beleive you can mix connectors and wiring... as long as they are NMEA compliant! I am wondering if one is NMEA 2000 (IEC 61162-3) and the other NMEA 0183 (IEC 61162-1)? I would very much question if splitting a port between the two with different NMEA formats will work? I have never tried that!

While I also think wiring is the issue - you are right, there is more to consider! And, they do make splitters for the different types of plugs! If dealing with an ICOM 402 or 502… you will have RCA plug or plugs! Depending on which and the type of radio defines the type of plug (if any) it uses. Some ICOM radios have one “RCA” plug, others have two, while others have ”9 pin”. I have not looked, but believe the ICOM use the same NMEA signal, just wired different, but the NMEA 2000 and 0183 on the same port?? If the GPS is providing a strong enough signal and wired right - even from the same port… it “should” work, provided each radio is using the same type and baud rate signal - If they use different signals you can (and probably will) get one that overrides, interferes, or cancel the other?

The first thing I would to, is check the GPS to see how many NMEA units it is designed to drive? If trying to attach more than designed for… your final results will be questionable, with or without a split or booster? Then I agree… wire each radio and get each working by itself - separately. And also agree, If it does have separate port available – use different ports! Once each radio works – wire’em together! YOU GOT to have them all wired and matched correctly and - if using the same port, with a splitter – has to have the same signal and baud rate! The link attached earlier shows the wiring of the different ICOM units.

BTW… this is only important if you are using your VHF for “commercial” applications, but “Every Class D I have seen here on VI has a separate Channel 70 receiver…” is NOT correct! They do “NOT” have a separate receiver, the receiver used can receive a separate signal… there is a difference, but for pleasure use (NOT COMMERCIAL)… it is a mute point and they are fine!

Most Class “D“… and "ALL” Standard Horizon radios are “ITU” and do “NOT” have separate receivers for Channel 70, only the GSX5000 and GSX5500 have an “IEC/EN” compliant approval for “commercial” use. Meaning “ALL” Standard Horizon have “ONE” receiver. Depending on the type of receiver, they have the ability to receive the separate signal for Channel 70! If the radio says ITU, I can pretty much guarantee it has a “Dual receiver” or "Double conversion superhetrodyne"!

And... also, I don't have to give any credits as, I wrote this "whole" thing!!!! Maybe I should copyright it? Oh wait... it already is! Not authorized for commercial use without written permission! [}][}]

 

[Kisinana]

GLG
RS-232 is commom for 9 and 25 pin layouts to carry DTE and DCE signals.
I have a 9 pin plug which I split and soldered my wiring to the pins.
The layout can be found at
http://pinouts.ru/SerialPorts/SerialMsx_pinout.shtml

Quick explanation is
Data out from GPS goes to Data in to radio as well the laptop and
Data into GPS is also Data out to radio

Here is the link with an explanation
http://www.boat-angling.co.uk/Hints_and_Tips/ConnectingGPStoDSC.htm
and this showed how this person worked out his connections
http://www.navagear.com/2008/05/crazy-nmea-wiring-ais-2-way-dsc/

Then I found my wiring diagrams for my radio and laptop and GPS then worked it out much the same way.

Another method if you have more equipment is to install a multiplexer

 

[GLG]

Kisinana nicely done. I get it. For others that are reading we are talking about NMEA 0183 not the NMEA 2000, that is a whole different kettle of fish and as far as I know cannot be mixed. So for clarity this is how Kisinana has his system wired.

GPS data out (transmit) to the Radio data in (receive)
Radio out (transmit) to the GPS data in (receive)
Here is the trick part
GPS data out (transmit) to the Laptop data in (receive)

The Laptop is eavesdropping to what your GPS is transmitting to the Radio.
That is where the splice comes in.
Notice that the laptop is not transmitting anything back to the GPS.

So for Searun he would wire his units like this
GPS data out (transmit) to the New Radio data in (receive)
New Radio out (transmit) to the GPS data in (receive)
GPS data out (transmit) to the Old Radio data in (receive)

His Old Radio would be listening to the GPS data but not be able to send data back to the GPS. Therefore it would not cause any data issues.

Kisinana did you tie the ground / shield wires together for all three?

This is what I like about this website. Guy’s sharing information and helping others.
On a side note I helped hook up a Lowrance to a Radio this afternoon and to my friends surprise it work right away. [8D]
GLG

 

[Charlie]

quote:Originally posted by GLG

On a side note I helped hook up a Lowrance to a Radio this afternoon and to my friends surprise it work right away. [8D]
GLG

No wonder you said thanks for that link.. that Lowrance diagram made your day on that one!

quote:Originally posted by Kisinana

Nicely done! Good explanation!

Now, unless someone knows something I don’t using that standard - the NMEA 2000 radio should also work? Knowing the difference between NMEA 2000 (a network) and NMEA 0183 (an interface) is transfer rate and that NMEA 2000 communicates with all NMEA formats, it should be fine hooking the “new” radio (NMEA 2000?) to the GPS and splicing in the “old” NMEA as indicated.

Here is a couple of good articles on NMEA if interested. The first is a real good explanation of NMEA and the second is good at explaining the difference in the two and what NMEA 2000 really is!
http://www.gpsinformation.org/dale/nmea.htm
http://www.nmea.org/Assets/nmea-2000-digital-interface-white-paper.pdf

 

[GLG]

Thanks Charlie, those links explain it well. If your Radio is NMEA 2000 than setup would be easy. So far I have only worked on budget radios that are not very capable. The one I worked on yesterday only had data in, no data out. So no way to send data back to the GPS. My friend wanted to be able to chart locations of other boats on his GPS. That will have to wait for the next radio, with data out.

Someone asked me why we need to have plugs on the ends of unused NMEA 2000 cables. Without getting into the electronic reasons, the best answer I heard was if you don’t plug the end, data will spill out the cable and fill the boat till it sinks. [:0]
GLG

 

[Kisinana]

GLG
Yes shields are grounded,but only on one end. If you ground both ends then you stand a chance of getting transient noise looping into the system.
Grounds are isolated at GPS and radio and tied together at ground pin on laptop.