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Marine HF-DSC-SSB, the GMDSS, "communications stool legs"

Radio/Satellite/Phone/E-mail

Marine HF-DSC-SSB, the GMDSS, "communications stool legs"

by ka4wja » Mon Aug 04, 2014 11:29 pm

Hello to all....
I attempted to post detailed answers to some queries on HF radio ("SSB") and sat phones, on another forum, but was unable to get the forum to accept them completely, nor format them correctly....
So, I'm going to post it all here and hopefully it'll all work okay...

And, up front....please have a look at this thread for some VERY important details about EPIRB's and what happens when you activate them....(and PLEASE read the links provided, especially those to SARSAT-COSPAS and to Beth Leonard's articles)...
EPIRB Activation? What happens/How to improve rescue odds
viewtopic.php?f=5&t=15457


1) Before I address the ease-of-use of HF radio ("Marine SSB" and/or "ham"), I think it would be good to make sure everyone understands the extreme ease, robustness, and reliability of the MF/HF-DSC signaling, which has been a part of the GMDSS for 20+ years now!!

(the GMDSS was established by the IMO under the SOLAS conventions in 1988, and became fully effective/operational in Feb 1992....and became mandatory for all SOLAS vessels and signatory nations in Jan 1999...)

So, this is nothing new....and we should all have been fully aware of the GMDSS now for at least the past 15 years, and have made every effort to utilize what parts of the GMDSS we can....


Parts of the GMDSS system that most find easy/affordable/useful (all within easy reach / affordable parts of the GMDSS for cruising boats...):

--- 406mhz EPIRB's (relatively inexpensive at $400 - $700, and easy to "sell" to cruising sailors..)

--- Marine VHF-DSC-FM (cheap and almost ubiquitous now-a-days...anyone that doesn't have a Class D VHF-DSC, REALLY needs to spend the few hundred dollars now!!!)

--- Marine MF/HF-DSC-SSB (HF-DSC is a VERY robust/reliable means of signaling.....and with reasonable costs of ~ $1800 new, ~ $1000 used, for an Icom M-802 MF/HF-DSC-SSB Radiotelephone....and simple-to-use, robust and reliable...it is an easy "sell", almost a no-brainer!!)

--- NAVTEX (inexpensive and very useful for most coastal sailors and/or those plying the Med, etc., with typical forecasts for waters out to 150 - 200 miles....but in some areas the forecasts are only for the next 24 hours, so other weather sources, such as HF-WeFax are recommended...) (and in US waters, the VHF-based NOAA Weather Radio system is widely used, so NAVTEX hasn't caught on in the US, as it has in Europe and the Far East...)
- WeFax....And while HF WeFax was not adopted officially as part of the GMDSS, according to a 2012 survey by the Joint WMO/JComm group, HF comms, DSC, voice, and data are used daily by a majority of ocean going vessels, and HF wefax being reportedly used daily by > 85% of them....so, for offshore/hi-seas weather info/forecasts beyond the "text" weather info provided via INMARSAT-C and some HF coast stations, HF WeFax still rules as the predominate "1st choice" when offshore, even in 2012, even for large ships / SOLAS vessels....)


Parts of the GMDSS that are a bit more expensive:

--- INMARSAT-C,
While INMARSAT-C might seem to some to be a bit pricey, at ~ $3000 - $3500, is a VERY viable communications tool to have on-board long-range cruising boats...as it gives, thru its FREE "SafetyNet" service, offshore/hi-seas weather info/forecasts (in plain text), position reporting and weather reporting thru NOAA and AMVER, and Distress Signaling....ALL FOR FREE....
NO monthly/annual subscription, NO Fees at all, until/unless you use it to send regular e-mails, and then you're just billed by the character/letter....
(and it is very robust/reliable....many orders of magnitude better than a handheld sat phone!!)


--- INMARSAT Fleet systems (such as F77) are pricey at $15,000 - $20,000 and are big/heavy, and use significant amounts of electrical power....
So, here if cruiser's desire hi-speed data / broadband internet access / etc., Iridium Pilot or INMARSAT Fleet Broadband systems (at ~ $4500 - $5000) are usually the typical choices....


--- SART's (X-band radar Search And Rescue Transponders) are reasonably priced at $600 - $800.....but are often over looked by many cruising boats, as they figure a working EPIRB in their liferaft will do them better...
And, if deciding between a second 406mhz EPIRB and a SART, I'd choose the second EPIRB!!! (but, if you're cruising in heavily-trafficked areas, with poor visibility, such as UK/North Sea, etc. then a SART would be a GREAT idea, and I'd recommend one before a second EPIRB...)


Anyone talking about "Marine SSB" in the last decade or two, should be talking about MF/HF-DSC-SSB....and those that are talking about 25 year old radios and "Voice radio watchstanding", etc. are unfortunately either ignorant of the changes in the past 25 years or are laboring under some serious misconceptions???

While it is not a requirement for our pleasure craft, the GMDSS has been a mandatory system for all SOLAS vessels, and all signatory nations, since Jan 1999....over 15 years ago...and regarding "SSB", please remember that nobody (except the USCG, Aus and NZ, etc.) does any "SSB Voice" monitoring or watchstanding anymore...and haven't for decades....
(as most "radio watchstanding" in the 1970's, 1980's and early 90's, before the GMDSS was fully implemented, was via "2182 watch receivers", which were silent until they received a two-tome alarm signal from another like-equipped merchant vessel, etc....so, understand that for most of the past 40 years, aside from the USCG, Bermuda Radio, Portishead Radio, Olympia Radio, Aus, NZ maritime shore stations, etc. and the old HF Hi-seas public coast stations, nobody has maintained a SSB Voice radio watch for many decades....and now in the recent 20 years, since the GMDSS has been implemented, and most HF Hi-seas public coast stations have closed, they are all monitoring MF/HF-DSC, 24/7....NOT an "SSB" Voice watch...)

{When I write "they", I'm speaking about the > 80 HF-DSC shore stations worldwide monitoring for HF-DSC signals 24/7, from all over the world....and the > 450 MF-DSC shore stations worldwide, that are monitoring MF-DSC 24/7, from vessels within 150 - 250 miles offshore....and the many hundreds of SOLAS grade vessels plying the seas/oceans worldwide 24/7 (many of them could be within a few hundred miles of you, < one day away...remember 500 miles can be covered by a container ship in less than 24 hours).... but again, except for the USCG, and a couple of others, nobody has a Voice radio watch anymore, and haven't for 15-20 years....all initial contact/signaling is done by DSC, and then further contact/coordination is done via "SSB Voice", only after signaled by DSC (or INMARSAT-C)....}



Here are the USCG Distress calling info....for vessels within range of the USCG stations....

http://www.navcen.uscg.gov/?pageName=cgcommsCall

http://www.navcen.uscg.gov/pdf/marcomms ... yAlert.pdf

http://www.navcen.uscg.gov/?pageName=AboutDSC

Please remember that while they were one of the last holdouts, the USCG no longer has MF/2Mhz voice or DSC capability and no longer monitor 2182 SSB, nor 2187.5DSC...
Effective 01 August, 2013, the U. S. Coast Guard will terminate its radio guard of the international voice distress, safety and calling frequency 2182 kHz and the international digital selective calling (DSC) distress and safety frequency 2187.5 kHz. Additionally, marine information and weather broadcasts transmitted on 2670 kHz will terminate concurrently.
The Coast Guard will continue to maintain a continuous watch on VHF FM channel 16 (156.8 MHz) and on existing voice and DSC frequencies in the 4/6/8/12 MHz bands as described in the Coast Guard.


Use MF/HF-DSC and then after initial contact via DSC, use the GMDSS SSB Voice calling / safety channels....


Here is a short video that shows real worldwide shipping, and their routes...have a look, and you'll see that most of our cruising routes pass near to, or in/thru, these ships paths....and we end up being close to, within a few hundred miles of, SOLAS vessels and/or within range of shore stations, along most of our typical cruising routes....
(but, unless we have MF/HF-DSC and/or INMARSAT-C we have no way of signaling these other vessels....and remember it is MF/HF-DSC that would allow you to signal another vessel for some non-distress assistance as well, such as if needing navigational or weather info, medical advice/info/supplies, fresh water, food, diesel fuel, etc...unless you are lucky enough to find a vessel within VHF-DSC range, it's going to be MF/HF-DSC or nothing...)

http://www.youtube.com/watch?v=xV0iRkAATCY



And, here is another video, that I've been hesitant to post, as it is 22 years OLD (from 1992), and has some errors and some unfortunate misinformation....But, it does give a decent overview of the GMDSS (as it was originally designed, and implemented in 1992..), so I think some might find it useful....just remember it is OLD and dated, with some errors...

http://www.youtube.com/watch?v=eRB7dUEUsDs

{Please understand that this is an OLD GMDSS explanation video (from 1992), and some things have changed! Please ignore the errors from19m 23s to 19m 36s, showing MF/HF and VHF radios that do NOT have DSC capabilities and note the old external DSC controller shown from 20m 17s to 20m 24s.
Also ignore the references to the old defunct INMARSAT-E beacons (now completely replaced by 406mhz SARSAT-SOSPAS EPIRB's).
Further take note of the old "2182khz Watch Receiver", which haven't been used in almost 20 years (at 20m 54s), shown listening to static (which they didn't do, as they were typically squelched and listening for a two-tone alarm generator alert (NOBODY monitors 2182khz anymore!)}


So, when terms like "SSB" are bandied about in our discussions on-line, I think we should all understand that this is not the 1980's anymore....and having a MF/HF-DSC-SSB Radio on-board is what we are talking about...
(those advocating using a 25 year old, non-DSC radio and a handheld sat phone, for communications when sailing offshore, would do well to understand the severe limitations such an approach has, and heed the words/comments from those who have found this to be a unfortunate choice...)

Please remember, that when out-of-range of VHF-DSC.....there are many shore stations and SOLAS vessels, listening on MF and HF DSC Frequencies 24/7....
And remember too, when you are beyond the range of a USCG helo (or Aus, UK Coast Guards), it is a merchant vessel that is most likely going to be your rescuer...
There are literally hundreds of SOLAS grade vessels out there plying the high seas, many within a few hundred miles of you..
{Again, when I write "many" shore stations and SOLAS vessels, I'm speaking about the > 80 HF-DSC shore stations worldwide monitoring for HF-DSC signals 24/7, from all over the world....and the > 450 MF-DSC shore stations worldwide, that are monitoring MF-DSC 24/7, from vessels within 150 - 250 miles offshore....and the many hundreds / thousands of SOLAS grade vessels plying the seas/oceans worldwide 24/7 (many of them could be within a few hundred miles of you, < one day away...remember 500 miles can be covered by a container ship in less than 24 hours)...}



Getting back to the particulars of MF/HF-DSC signaling...

In addition to the SITOR-FEC (Forward Error Correction) nature of MF/HF-DSC, which is incredibly strong and robust, AND the repetitive sending of the message (over-and-over again), MF/HF-DSC also has a significant signal-to-noise advantage over SSB Voice communications.....
MF/HF-DSC is about 15db better than an SSB Voice circuit over the same path, on the same band/frequency, etc.
This 15db S/N advantage is like going from a 150 watt SSB radio to a 5000 watt SSB radio...


The simple one-button DSC-Distress, sends out a multiple of DSC distress calls on 8mhz, over-and-over, without any further human interface...until a response is sent or until you cancel the call...
And a "two or three button press" DSC-Distress, sends out multiple DSC distress calls, over-and-over, on 8mhz, 12mhz, 16mhz, 2mhz, 4mhz, and 6mhz, and continues over-and-over again, without any further human interface...(and you can also select another freq, should you desire)...until a response is sent or until you cancel the call (or until electrical power runs out)...

Please understand that while the radio is transmitting your DSC-Distress call it is also listening for a response from a shore station/RCC and/or other vessels, and while it is standing-by waiting for this DSC ACK response (approx. 3 minutes of standing-by/waiting between DSC calls), it is ALSO monitoring/listening on the GMDSS VOICE Distress / Calling frequency that corresponds to the band that the DSC call was placed in....all automatically!!

Here is a video that shows what the M-802 does, live, in the real-world, when you press the Distress button...

http://www.youtube.com/watch?v=LgnBiGNbWNU

This means that with just a press of a button or two, your MF/HF-DSC-SSB Radio is sending out very detailed/accurate position information, as well as your MMSI# (which gives the shoreside RCC's all your vessel info, size/type/color, equipment on-board, communications capability, liferaft/survival craft, etc. as well as your shoreside contact information), and if you've selected a "distress type", the exact nature of your distress....AND it is waiting for an acknowledgement of your DSC call on both the GMDSS DSC channel/freq and on the appropriate GMDSS Voice SSB channel/frequency....AND it does this automatically....

And, if you've selected a "six freq DSC Distress call" it is doing this on all six GMDSS DSC calling frequencies from 2mhz thru 16mhz...thereby assuring that your distress call will get thru to shore stations / RCC's (and other vessels), regardless of time-of-day or radiowave propagation of the moment...all automatically....(thereby eliminating the need for a trained radio operator, nor any trained personnel at all!!)
And, even if you selected just the "default" / 8mhz DSC call, during the daytime this would typically get thru to shore stations within 1000 miles of you, and all HF-DSC equipped SOLAS vessels within 600 - 1000 miles of you....and at nighttime this would get to shore stations, and other vessels as far away as 3000 - 4000 miles....
Again, all automatically, without any need for "trained" / "experienced" radio operators....

And, this is/was one of the basic goals / principles of the GMDSS....allowing multiple / redundant (and robust / reliable) ways of signaling shore stations and other vessels, WITHOUT the need of trained radio operators....

Using 406mhz EPIRB's, VHF-DSC, MF/HF-DSC, INMARSAT-C, allows for all of these goals to be realized!!!
(although many/most cruiser's feel not having INMARSAT-C is not too much of a detriment, and some compliment the other GMDSS equipment with a consumer sat phone, such as Iridium, and feel this adequate for them..)

But, remember that while "SSB Voice" is used for further contact/coordination (after initial contact by DSC, or INMARSAT-C), SSB Voice" is NOT monitored (except by USCG, etc.), and as such when we use the term "SSB", we should all understand that this is MF/HF-DSC-SSB, NOT 'SSB Voice".....




2) Dan's perception here is understandable...and I'm sorry that this has resulted in some misconceptions...
It may sound weird but when you state "40 years of experience"....[and someone else] states, "doing this since I was 12." It indicates that you need 30 years of practice to make this work - I know it doesn't but it is a perception that this stuff takes "years" to understand and master hence the idea that it is complicated.
To be clear, this perception doesn't sound weird at all....it is completely understandable....(but, hopefully I can show how this perception can be reversed....or at least understood to be inaccurate...)

Sorry-to-say, that statements about experience have actually become an unfortunate "common internet discussion procedure", used to actually get accurate/believable information (as opposed to misunderstood Wikipedia-sourced info and/or info regurgitated from magazines, boat-shows, etc.), through to those that inquire on-line....

I used to just give some facts....but that just started arguments...and even had some guys say that there is no such thing as "facts" in on-line discussions, as it is all opinion!!
Then I would briefly answer the query, and list many links to detailed facts/further info....but have found that few actually follow the links and read them....

So now, it is getting difficult to actually get the facts out there... :)

In my opinion this is unfortunate....as scientific facts are just that, facts....


Okay, I'm rambling a bit here...
The point is, you do NOT need years of experience to make proper use of HF communications....and it is an unfortunate fact-of-life that this misconception continues...

Hopefully, I can alleviate his tentativeness a bit...
I am a tentative SSB fan - I am waiting for someone to post a thread that says - "Bought Radio Model XYZ, plugged it in and it works."
My late father had NO electronics knowledge nor training, and was not a "high tech" guy at all...you know the type, WWII vet (10th Mountain Div), construction worker, and then a self-made, small businessman....
Way back in the mid-1960's, I remember him using our old 2mhz AM marine radio in the Bahamas and down-island....and having little success when more than 150 miles from Miami and/or San Juan (I learned why this was "typical", in the early 70's)....and in the early/mid-70's, I taught him how to use his new Marine "SSB" Radio (an SG-714 "SGC Intercontinental One", 12 - 24 channel, crystal-controlled HF-SSB radio), and from '76/'77 thru late 80's (when I installed a new Icom for him), he used that radio almost everyday when at sea and even in port...and in the late 70's, I remember placing telephone calls on-board from all over, even the eastern Med (via WOM and WOO, 6000-7000 miles away), after spending hours waiting for an "international line" at some telephone office in Turkey, Greece, Egypt, etc. (remember that back then, there were no direct dial international phones in many cities in these countries...and even if you did find one, the connection was terrible, and the cost was about the same as making a call from the boat, which at that time was $5 - $10/minute!)

My Dad was NOT a radio guy at all....and he mastered the Marine SSB in a few attempts over a few days...


Fast forward a few decades and now it was my sister (10 years my senior, and while intelligent, she is also a "non-tech" person, having degrees in journalism/poly-sci).....
I was able to teach my sister how to use my Icom M-802, to listen to weather, to call a distress, call USCG, call WLO, place phone calls, etc....al in just an hour or two....and have written a couple basic steps on a laminated 3 x 5 card, to assist anyone unfamiliar...

And, I used her and my 93 yr old ocean sailor of a mother (a VERY non-tech person) as my 2 person "focus group" to critique my videos....figuring if they understood them, anyone else should be able to do so...

Icom M-802 Instr Videos(basic-adv) & LIVE DSC-Distress Call
viewtopic.php?f=5&t=16779



3) While I have posted links to my videos before, if you wish to read things and/or desire further details / info...here are some pages that will help...

EPIRB Activation? What happens/How to improve rescue odds
viewtopic.php?f=5&t=15457

Offshore / Hi-Seas Weather data / forecasts
viewtopic.php?f=5&t=13712

Tips for using an HF-SSB Radio (mostly for newcomers) (mainly for those with OLD radios..)
viewtopic.php?f=5&t=13306

HF Radio Freqs, summertime Atlantic crossing, offshore Net.. (lots of detailed info/background....explained well though...:)
viewtopic.php?f=5&t=13270

Icom M-802 DSC-Distress Signaling, what really happens!
viewtopic.php?f=5&t=16705


And, here are links to the HF radio videos and detailed discussions...

http://www.cruisersforum.com/forums/f13 ... 14734.html

Icom M-802 Instr Videos(basic-adv) & LIVE DSC-Distress Call
viewtopic.php?f=5&t=16779



4) As far as the various legs of your "communications stool"....the SOLAS conventions and the GMDSS have already dealt with that and have adapted as needed over the recent years (see all the info above)...and reinventing the wheel is not necessary here, just learning about the 20+ year old GMDSS, and utilizing as many parts of it that you can afford, both in $$$ and in electrical power and space on-board!!

And, see photos of my Nav Station just for some ideas/examples....
Image
http://www.c470.jerodisys.com/470pix/4714801f.jpg

Image
http://www.c470.jerodisys.com/470pix/4700307f.jpg

Image
http://www.c470.jerodisys.com/470pix/4700319f.jpg


And, FYI, everyone should read this thread and follow the links there (especially those to SARSAT-COSPAS and Beth Leonard's articles)
EPIRB Activation? What happens/How to improve rescue odds
viewtopic.php?f=5&t=15457



See details above....
I view HF/SSB as one leg of the communications stool that now includes satphone. satphone is "on the rise" in terms of lowering cost, variety of products and utility of use.

As you can see, on-board my boat, for sailing the N. Atlantic, Caribbean, Med, etc....

I think of HF-DSC-SSB as one part of the "communications stool", 406mhz EPIRB as another part....and then either my spare HF-DSC-SSB radio, my two VHF-DSC-FM radios, and/or "ham radio", and/or marine SSB voice (USCG and WLO), as my third / fourth part (and I DO have a spare Icom M-802 on-board, so it can be used the third leg of my tripod...)
And, if heading farther off the beaten path (such as a circumnav, etc.), I'd equip with INMARSAT-C in a heartbeat....

And, as long as you (and others) understand that it is DSC that is important here....MF/HF-DSC is what we are all talking about, when speaking of "SSB", not a 25 yr old non-DSC HF radio!!!

And, while I understand that some will chose a "sat phone" as part of their "communications stool", I caution them to remember that a handheld sat phone is NOT the easiest thing to use, even in calm conditions....and when the weather is rough, they are damned near impossible to use...(and remember they don't work below decks)...
Shouting your coordinates into a handheld sat phone while hanging on for dear life in the cockpit, isn't my idea of a useful part of my communications stool... :)
Installing an external antenna and below-decks docking station is going to be an almost necessity for anyone deciding to use a "sat phone" as part of their communications stool...




SSB is not going to get any easier and at some point may no longer be a "necessary" leg in the communications stool.
Actually Dan, "SSB" IS getting easier to use and more reliable!!!
(see info and videos, above)
I'm still amazed that somehow this "myth" seems to propagate....

(I'm not saying that everyone needs an "SSB"....but it IS getting easier to use them, and they are certainly NOT going to be "unnecessary" for a long time to come...at least another decade or two...)

I'm not sure why that myth pervades, but with Maritime HF communications (DSC, data, and Voice) being used daily by a majority of ships at sea (an actual fact, from the WMO/Jcomm survey in 2012), and with > 80 HF-DSC shore stations, and > 450 MF-DSC shore stations, and many 1000's of SOLAS ships at sea....it is clear that "SSB" (MF/HF-DSC-SSB) is still a necessary part of the communications stool for those venturing offshore and/or across oceans, and will be for many years to come...




I will readily admit that I have not gone deep into your videos and instructional posts - I am not at the point where this decision needs to be made. But in the meantime I try not to be a detractor of HF. Just educating myself slowly and observing the dialog.

No need to wait 'til decision time....just read the above, follow the links, and watch some of the videos (the ones here in this thread, at least), and you'll be well on your way to nirvana :) :) :)
Seriously, if you do this, you'll be ahead of 95% of the cruiser's (and wannabe cruisers) out there...




The comms plan needs to be redundant and reliable.

This is one of the PRIMARY functions of the GMDSS....(see above)



Currently SSB is a separate system from VHF and satphone and that makes it a level of redundancy that is useful to have on board, if one can afford it.
I personally would choose satphone over HF if my funds limited the types of equipment I could afford.

If you read the above info, follow the links and read them, and watch the videos, you may change your mind on what is a higher priority....

But, even if you do not change your mind, you will be come MUCH better informed / educated on these matters.....and THAT is really what my goal here is....(not to change anyone's mind, but rather to just honestly inform them as best I can...)




I do hope this helps!!!
Fair winds to all...

John
s/v Annie Laurie
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110

(currently lying, Sewall's Point, FL)

~~~~

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ka4wja
Posts: 1137
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Location: Florida
Vessel Name: Annie Laurie
Vessel Make and Model: Catalina 470 monohull sloop

Re: Marine HF-DSC-SSB, the GMDSS, "communications stool legs

by Tomkaat » Tue Aug 12, 2014 6:08 pm

John,
Thank you, thank you, thank you, for putting this stuff out there. I am just getting comfortable with my marine station. I have airmail up and now am trying to the WeFax to work. After reading this i am back to confirm the DSC configuration of the station and look at a GPS connection. Katface has a series of ever newer GPS antennas onthe top of the hard bimini. I want to check for a possible networked one first as i seem to remember a reference to NMEA 0183 in the 802 manual. There was a broken whip antenna back there as well - perhap this was for DSC. I am pretty sure i only have a single VHF whip on top of the mast. Will the DSC whip work at an elevation of 10 feet rather than 75?

Regards,
TV
OFFLINE
Tomkaat
Posts: 11
Joined: Sun Jul 22, 2012 9:40 am

Re: Marine HF-DSC-SSB, the GMDSS, "communications stool legs

by ka4wja » Tue Aug 12, 2014 9:14 pm

TV,
You're very welcome...
But, before you go any further, I have two important things to note....

1) Most of the above info on the GMDSS, etc. is not intended as "instruction" for operating, nor installing the M-802....

2) The videos noted/linked to above ARE intended for the new M-802 owner (or any sailor new to HF comms), to learn how to use the radio effectively....

So, my best advice, up front is to watch the videos....then ask specific questions in this thread...
Icom M-802 Instr Videos(basic-adv) & LIVE DSC-Distress Call
viewtopic.php?f=5&t=16779



3) Please also have a look at the videos and these other threads...
Especially these first two!!!

Tips for using an HF-SSB Radio (mostly for newcomers)
viewtopic.php?f=5&t=13306

Offshore / Hi-Seas Weather data / forecasts
viewtopic.php?f=5&t=13712


USCG Discontinued ONLY 2mhz Distress Watchkeeping 8-1-2013
viewtopic.php?f=5&t=15726

Icom M-802 Instr Videos(basic-adv) & LIVE DSC-Distress Call
viewtopic.php?f=5&t=16779

EPIRB Activation? What happens/How to improve rescue odds
viewtopic.php?f=5&t=15457

Icom M-802 use on the Ham Radio Bands
viewtopic.php?f=5&t=16707

HF Radio Freqs, summertime Atlantic crossing, offshore Net..
viewtopic.php?f=5&t=13270

Icom M-802 DSC-Distress Signaling, what really happens!
viewtopic.php?f=5&t=16705



Icom M-802 "Clipping Issue" - Revisited....
viewtopic.php?f=5&t=12547

IC-M802 Compression
viewtopic.php?f=5&t=4791

Re: KISS-SSB Counterpoise
viewtopic.php?f=5&t=13490&start=75




4) A few specifics here, just for clarification...
Tomkaat wrote: I have airmail up and now am trying to the WeFax to work.
This is an unfortunate common occurrence....getting computers / data comms working before actually getting the Voice and DSC features working....and many times, not fully understanding how they work (hence the reason I made the videos...)
Fact is, "Voice" communications with the M-802 is cinch....and the DSC signaling is just pushing a few buttons....all of that is far easier than using a PACTOR modem/laptop, etc....
And, WeFax....well, that's also easier than PATOR modems/laptops, etc....see above referenced threads for the details...




After reading this i am back to confirm the DSC configuration of the station and look at a GPS connection. Katface has a series of ever newer GPS antennas onthe top of the hard bimini. I want to check for a possible networked one first as i seem to remember a reference to NMEA 0183 in the 802 manual.
You MUST have a MMSI# in order for the DSC functions to work (which is included with your FCC Ship Station License).....and of course you must also a FCC Ship Station License (and radio operators lic/permit), in order to use you M-802 on any marine HF frequency (Voice, DSC, data, Sailmail, etc.)....

I recommend a separate dedicated GPS for your DSC radios (one GPS for both the M-802 and your VHF-DSC Radio)....I use a Garmin GPS 76, mounted at the Nav Station (no external antenna needed!)...
But, should you already have an extra NMEA 0183 output GPS, then connecting this to your M-802 and VHF-DSC radio would be fine....(although, I still recommend that this is not your main/primary GPS)





There was a broken whip antenna back there as well - perhap this was for DSC. I am pretty sure i only have a single VHF whip on top of the mast. Will the DSC whip work at an elevation of 10 feet rather than 75?
I think you are misunderstanding what the difference is between "MF/HF" and "VHF", whether it be Voice or DSC, there is VHF-Voice (i.e. VHF-FM) and VHF-DSC....and MF/HF-Voice (i.e. "SSB") and MF/HF-DSC...
A "VHF" antenna will NOT work for HF, nor vice-versa....(although some HF-DSC antennas do resemble a marine VHF antenna whip, they are NOT the same antennas and will not work with each other's radio)

Class D VHF-DSC radios require only one antenna for both Voice (FM) and DSC....
Class E MF/HF-DSC-SSB radios (such as the M-802) require a main antenna and a DSC receive antenna...

I have no idea what you have installed on your boat, nor where you are located, nor who/when these radios were installed, nor by who, nor how they are wired....
These are things you will either need to ask the people that installed them, or find out for yourself by tracing the wiring (yes, that is a PAIN in the ass, but it is the best way to do it....)




I hope this helps you out...please ask any other questions you may have, but be sue to include more info on your installation (as I write above), so we can help further....the more info, and more details...the more help we can be,,,

Fair winds...

John
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110

(currently lying, Sewall's Point, FL)

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Re: Marine HF-DSC-SSB, the GMDSS, "communications stool legs

by Tomkaat » Thu Aug 14, 2014 1:04 pm

Thanks for the reply John,
I have MMSI, radio, and ham licenses.
I am talking about tracing wires and want to spend some time understanding what is currently connected where on the HF radio. I believe i also have a DSC VHF radio too.
I saw your GPS setup on the video. If i don't need to route to an external antenna then that makes sense. Certainly basic GPS has become very inexpensive. I can evaluate with my old hand-held. The fact that i now have 5 hard mounted external GPS antennas makes me a bit leery about a sixth for the DSC.
As far as VHF and HF i was trying to understand what the DSC antenna would look like. I had two whip antennas on the boat about a meter long. The picture I found for a DSC antenna looked like one of these. I don't get how a 1 meter long (VHF like) antenna will receive a HF DSC ACK unless the ACK signal is in the 1 meter range. Seems like that would be a major propagation problem. I can't picture another HF antenna - only have one backstay. Anyway if the DSC receive antenna is really about a 1 meter whip then it is possible that the broken whip on the aft bimini was a DSC and not something else and i can just put a replacement antenna up. Keep your fingers crossed.
Still wading through all your information.
Thanks again for your efforts,
TV
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Re: Marine HF-DSC-SSB, the GMDSS, "communications stool legs

by ka4wja » Fri Aug 15, 2014 6:15 pm

Tomkaat,
Sounds like you're progressing....
Maybe I can add a few thoughts that might help further...

[Please note that you've made no mention of your boat, where you are located, what nation's flag your boat is registered under, what your nationality is, etc....
So, I'm using US and FCC rules/regs....if your vessel is flagged otherwise, please let us know so we can adapt advice better suited to your situation....also telling us WHAT boat you have, HOW it is equipped, WHERE you are at, etc....are also important to providing accurate info and on-point advice, rather than rambling on and on about generalities....:) ]



Tomkaat wrote: I have MMSI, radio, and ham licenses.
I believe i also have a DSC VHF radio too.
Good that you have a ham license....but dealing with the M-802 on the marine bands, you will need an FCC Ship Station Licenses and Operators lic/permit, and I assume you have those as well, as you mention that you DO have a (new?) MMSI#....
Remember when you transferred the vessel to your name, etc. you must change the FCC Ship Station License.....and you'll receive a new callsign and MMSI#....
(although just this past week, I read that if you fill out the Ship Station License Application and include your old MMSI#, this MMSI# may be reassigned to you....not sure if this is currently official FCC Policy, or just some level-headed thinking on part of some FCC folks...)

The reason I'm rambling on about the MMSI# is that if you've followed the correct procedures, you'd need to re-program your new MMSI# into BOTH the M-802 and you VHF-DSC radio (or at least verify the numbers in each are correct, if the FCC reissued the old/original MMSI#'s to you)....as without the MMSI# programmed in, neither radio will send a DSC message...




I am talking about tracing wires and want to spend some time understanding what is currently connected where on the HF radio.
This is probably the best way....as it teaches you a lot about your boat and how it is wired...



I saw your GPS setup on the video. If i don't need to route to an external antenna then that makes sense.
I have no idea what boat you have, but if you have metal decks (or even an alum or steel hull), you're not likely to get good results from GPS units below decks....but for most of us with fiberglass boats/decks, there is no issue at all!!



The fact that i now have 5 hard mounted external GPS antennas makes me a bit leery about a sixth for the DSC.
Wow!! 5 GPS antennas...
I have my primary GPS (Raystar GPS 125+) mounted on the aft rail, at the height of the bimini / solar array...(and I carry a spare in a locker below)
I have my AIS transponder GPS antenna on top of a locker, just below the deck...
And, my Garmin GPS 76 (for my DSC radios) mounted at the Nav Station...
(if I add an INMARSAT-C terminal, its ext antenna also includes its GPS antenna....and it all does need to be mounted securely out in the clear..)
But, I can't imagine anyone needing 5, but maybe you've got a lot of redundancy...




As far as VHF and HF i was trying to understand what the DSC antenna would look like. I had two whip antennas on the boat about a meter long. The picture I found for a DSC antenna looked like one of these.
I don't want to get into a long explanation / discussion of the robustness and signal integrity of HF-DSC, but suffice to say that your M-802's DSC receive antenna is used to receive HF-DSC calls on the six int'l GMDSS DSC freqs (and for most "cruisers", primarily an ACK of their own DSC call), and it can be a relatively small and inefficient antenna (assuming it is wired correctly and mounted in the clear)....
Although I originally used the Metz 54" long (1.4m) whip antenna, I found using one of my lower shrouds (insulated), at about 23' long (7m) to be a much better receive antenna (and I also simultaneously use this as my wefax receive antenna)....

Perhaps one of your antennas is like this Metz unit??

http://www.metzcommunication.com/weatherf.htm



I don't get how a 1 meter long (VHF like) antenna will receive a HF DSC ACK unless the ACK signal is in the 1 meter range. Seems like that would be a major propagation problem.
Again, you would NOT be using a "VHF like" antenna.....just because they "look" alike, they are NOT alike....
And, your concern over using a 'short" antenna for "long" wavelengths is understandable....as I wrote above, HF-DSC is a robust and highly reliable means of signaling, but yes a longer antenna would work better....

It's just all a matter of "how good" you need your HF-DSC receive to be, vs. how much money do you wish to spend, vs. how much room/space do you have, vs. how complex/complicated do you desire your on-board system / set-up to be??
All questions that you'll answer for yourself....




I can't picture another HF antenna - only have one backstay. Anyway if the DSC receive antenna is really about a 1 meter whip then it is possible that the broken whip on the aft bimini was a DSC and not something else and i can just put a replacement antenna up.
Again, please see if this Metz antenna is what you have...
http://www.metzcommunication.com/weatherf.htm
http://www.docksideradio.com/Icom%20SSB%20Radios.htm


Keep your fingers crossed.
Still wading through all your information.
Thanks again for your efforts,
TV



I hope the above helps...
Fair winds...

John
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110

(currently lying, Sewall's Point, FL)

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Re: Marine HF-DSC-SSB, the GMDSS, "communications stool legs

by Tomkaat » Fri Aug 15, 2014 6:52 pm

John,
Redundancy is right. All the old systems are still working and I just added two more to support b and g mfd and ais. One of colleagues worked on the system and confirm that you do not need a long HF antenna to receive the ack as well. The antenna that I took down looked exactly like that but there is nothing currently hooked to the "front" connections to the m802 for the dsc antenna. I also have two VHF radios so it could have been a secondary VHF antenna. Another mystery to solve.
Katface is an older Swan. Lots of fiberglass.
One question for you. Does your garmin gps support the correct 0183 data? Did you need to build your cable? There is already something connected to the gps port on the 802 but the unit does not report position.
Regards,
TV
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Re: Marine HF-DSC-SSB, the GMDSS, "communications stool legs

by ka4wja » Mon Sep 01, 2014 5:21 pm

With the fall outfitting season starting, and with Atlantic-Crossing season / US-to-Caribbean passage season both coming up, I thought some may find this information helpful...


And, TV, sorry I missed your questions until today...
Tomkaat wrote:Does your garmin gps support the correct 0183 data?
Yes....

Did you need to build your cable?
No, I used the Garmin "power/data" cable (~ $15)...

There is already something connected to the gps port on the 802 but the unit does not report position.
Probably either a wiring/connection issue, a GPS/plotter output issue, or just a confused wiring / set-up issue....I'm not there, so I cannot be precise...




Fair winds...

John
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110

(currently lying, Sewall's Point, FL)

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Re: Marine HF-DSC-SSB, the GMDSS, "communications stool legs

by ka4wja » Sat Jan 02, 2016 12:11 pm

With all the discussion about DSC, etc., I thought some may wish to glance at this thread again.

I hope this helps some of you.

Fair winds..

John
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110

(currently lying, Sewall's Point, FL)

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