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Old 13-06-2019, 16:57   #1
kcj
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Ssb dsc quandary

A buddy and I have been reading/YouTubing up on ssb operations. We are about 800nm apart. This afternoon we were testing out the dsc function as per Annie Laurie’s direction. (Many thanks, very helpful) I was able to get one test to MNM on 4m to work... two hours later no go, figured it was time of day.

My buddy and I succeeded in conversing on 16m, with good reception on both ends. On 12m we could just hear each other, and 8m and 4m were a no go.

Our quandary is we could not get the dsc to work . Understandable for 4,6,8, and 12m, but figured it should have worked for 16m, as we could converse on 16m... I believe we successfully transmitted, as we both got to “wait for ack”, while the other was on dsc watch...but neither of us got a receive while on dsc watch. we triple checked the mmsi numbers.... waited several minutes before cancelling....

My only guess is that the dsc watch RX frequency is slightly different than the TX frequency in the call frequency function, and they appear to come in pairs as I can only select the TX row.. no idea how to remedy this if it is the issue...

Any thoughts on what we are missing?

Many thanks in advance.
John
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Old 13-06-2019, 21:19   #2
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Re: Ssb dsc quandary

Did you check the NAVCEN schedule? I can say that there is some activities on 14MHz, but not real strong activities. At 800KM 8MHz to 12MHz would probably have been your best bet depending on time of day.

https://www.navcen.uscg.gov/?pageName=cgcommsCall
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Old 14-06-2019, 04:35   #3
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Re: Ssb dsc quandary

Upon further review....it seems I need to reprogram the scan frequencies...more research to be done on the hows and whys of that....
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Old 14-06-2019, 06:51   #4
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Re: Ssb dsc quandary

If you're using the icom m802, there's also a separate DSC "receive" antenna to install.

If you don't have that, you're not going to receive DSC properly, or possibly not at all.

Cheers.
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Old 14-06-2019, 07:25   #5
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Re: Ssb dsc quandary

Have an 802...

How big does that secondary antenna need to be? The one on my boat is just a 15' wire that terminates in a deck fitting....

Does that apply to routine in addition safety urgency and distress calls?

Thx
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Old 14-06-2019, 07:57   #6
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Re: Ssb dsc quandary

The one that we used, I thought, was a shakespeare antenna. It looked exactly like a vhf antenna, and I'd be surprised if it wasn't. I don't think a straight wire would do the job. It was sold to us by the same folks who sold us the radio.

This one claims to do the job. https://www.sea-tech.com/product/met...icom-m802-ssb/

Having said that. I never had any luck calling a station with DSC. We received all sorts of distress calls over DSC, so it worked, but Icom's software isn't that intuitive, and we tried for a couple of hours, then gave up.

You'd think they'd make it easy like the vhf radios are... This was in 2006, so the software may have changed.

Cheers.
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Old 14-06-2019, 11:09   #7
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Re: Ssb dsc quandary

John (kcj),

I'm tied up working at client's office....so, cannot get on-the-air...
But, is there a way we could talk on the phone today?? I can call you...

The M-802 (and other MF/HF-DSC-SSB Radios) were designed primarily for DSC "Distress" signaling to coast stations and other vessels, and "Routine" DSC signaling to coast stations....and as such most small, private vessels ("cruiser's") have found the use of DSC signaling to/from each other to be problematic at best!
Yes, they do work....but, you really should have a DSC rec antenna, AND know how to use/program the radio...


If we cannot connect via telephone, then please re-watch the videos, as you are misunderstanding these things:

1- The M-802 has a built-in DSC Receiver (with its own dedicated antenna connector) that is ALWAYS monitoring all six int'l GMDSS freqs, listening ONLY for "Safety", "Urgency", and "Distress" DSC messages....all the time the radio is turned on...
It does this in the background, and there is no display showing this is happening, until it decodes a message....but it IS happening!
And, this has nothing at all to do with the "DSC Watch Mode"..
BUT...

2- But, if you (and/or your buddy) do not have a DSC receive antenna connected to the M-802's DSC Receive Antenna connector, you will not receive any DSC "Safety", "Urgency", or "Distress" messages from other vessels (or coast stations)....except in response (ACK message) to your own "Safety" call, or "Test" call....the reception of these ACK messages from your own "Safety" or "test" calls, comes from your main antenna, not the DSC receive antenna...other DSC calls (not acknowledgements/ACK of your own calls), are received via the DSC rec antenna...

It seems like you do not have a DSC antenna connected to your radio?

{trying not to add more confusion, but when specifically waiting for a response to a DSC "Distress" Call, the radio is using the DSC Rec antenna waiting for a DSC response (ACK), and at-the-same-time the radio is using the Main antenna to listen for an SSB Voice response on the designated SSB Voice Traffic freq/channel...again, this is confusing to those new to HF maritime comms....which is why I made the videos...}





3- If, in your example of the tests you ran with your buddy, you were sending an individual "SAFETY" DSC call, on one of the six int'l GMDSS DSC freqs (which I assume you were doing?), and your buddy did not have a DSC rec antenna, he would not receive your DSC call...so, your lack of success is not surprising...

4- If you were trying a "Routine" call, even if he did have a DSC receive antenna, the dedicated DSC receiver inside the M-802 would not alert him that it was receiving a call...as it will only alert for "Safety", "Urgency", and "Distress" messages...


Be sure to watch the whole HF-DSC Playlist
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX



Please note That the "DSC Watch Mode" is complete different....and is covered in a different video....and is almost completely unused by most M-802 users....(and while I can explain all of this as well, I don't wish to confuse further)



I hope this helps...
If you wish me to assist via telephone, please send me your number via PM (Private Message) here....and I will call you...

Fair winds.

John

P.S. The fact that you were able to talk via SSB Voice on 16mhz, from a distance of 800 nm, is a bit unusual....but not too surprising...
But, the fact that you were NOT able to do so on 12mhz is surprising...and I suspect local noise (receive noise) as the reason...

But, in any case, I have videos on that too...
Have a look at the first two videos in this playlist:
https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y
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Old 14-06-2019, 14:37   #8
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Re: Ssb dsc quandary

Very nicely explained. The software seems more complicated than necessary, but you've done a great job explaining how to get the job done. When I get my next radio, I'm sure I'll have a handle on it, with the aid of your video. Thank you.

When I took my restricted radio course, we used marine commercial units. They were very easy to use, and send/receive dsc calls. Then when I got my own unit, M802, I was stymied as to why it was so difficult.

Thanks.
Paul.
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Old 14-06-2019, 16:00   #9
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Re: Ssb dsc quandary

Paul, et al,
You're welcome!!

This is the inherent problem with classroom simulators (whether DSC, RADAR, etc.)....the real world is different!
Since they try to get you through the class successfully, they almost always just do a simulated / classroom demo of a MF-DSC call, and not even bothering to mention the added complexity of the HF-DSC system...further they assume that the radios will be properly, and professionally, installed!!



And, this is why I made these videos, LIVE, as-it-happens, in the real-world, with the real radios, with the real ionosphere, with real noise / real interference, LIVE, without a script, without pre-planning, etc., LIVE on a real offshore cruising boat floating in the sea water (tied to a dock), saying/showing the year, time-of-year and time-of-day, etc....
All, just like all of my fellow sailors / cruisers face on any random day!!
Not in a classroom!!


If I might add something further??

The M-802 operates the same way other MF/HF-DSC-SSB Radiotelephones do...except for some ancillary/auxiliary functions of "Class A" GMDSS radios, versus the features/functions of Class E radios, the M-802 and its DSC functions are the same....under IMO/GMDSS rules, it must be this way...
I know, I know....many people want to blame Icom...and to be clear the Icom M-802 manual is CRAP!!! But, the radio works exactly the way the IMO/GMDSS rules say it should for a Class E MF/HF-DSC-SSB Radiotelephone!! It's just that few actually teach that...


Bottom line:
Install the system properly (and that includes an effective DSC receive antenna), watch the videos, and it will work!!
And, it will work seamlessly....especially if you watch the videos before you read the Icom manual...(or maybe not even read the manual??)


So, why is there such confusion / discrepancy??

Mostly for 3 to 4 reasons...
a) Even if taking a class/passing a test....this uses "simulators"....so, there is a lack of actual real-world training / understanding of how the HF-DSC system works....and this applies to those teaching the darn GMDSS classes, too!! Most of them are not experience radio ops!!! (I mean, why not actually hire radio operators / radio engineers to teach these classes, rather than someone that "passed the test" / has got some "sea time", etc., but has little, to none, real-world experience in actually operating an HF-DSC-SSB Radio, let alone troubleshooting an HF-DSC-SSB system??)

b) Improper installation of the HF-DSC-SSB radio / system....this means that few small, private boats / cruising boats have actually installed an effective, dedicated HF-DSC Receive antenna!!!
The radios (MF/HF-DSC-SSB Radios) are designed to have this separate, dedicated DSC Receive antenna....and when installed/connected properly, the radios do operate seamlessly (at least as well as the GMDSS / DSC design rules allow)!!
But, if there is not an effective separate DSC Receive antenna, the radio's functions are stymied to actually do what they are designed to do...hence people get frustrated and say things like "this DSC stuff is a joke"....(I've actually read those words from someone that had completed a LRC course and couldn't get his M-802 to work properly....he didn't have a DSC Receive antenna!)

c) The fact that the original DSC system was designed >20 years ago....and as time / technology moved on, the DSC system stayed the same....
What I'm getting at is: Aside from the DSC Distress signaling (going to all coast stations and all vessels), the HF-DSC system was primarily designed as a way to "signal" to/from a vessel and a coast station, for telex and telephone traffic handling....So, most of the DSC Functions (again, aside from DSC Distress, Urgency, Safety, signaling) are designed for use in "duplex mode" for use between public coast stations and commercial vessels...and not designed for us "cruisers"....

d) And, in most GMDSS instruction classes (and radio classes, such as LRC classes) they use "simulations"....mostly real radios, but only sending to/from those radios there in the classroom / lab....not communicating with others out in the real world....
AND...
And, since most class demonstrations use MF-DSC, rather than HF-DSC....where MF-DSC is the one part that is designed as "simplex"...


If you add up those 3 - 4 things, you can easily see why most cruisers who have M-802's haven't had much success in using the DSC functions...



If you watch these playlists....you'll see how to actually use / operate your HF radio (especially the M-802)...do not think that watching just one video will give you all the info you need, it will not!! Please watch they playlists!! (you can fast-forward or skip the parts that are duplicate / redundant, but please try to watch the playlists, as the videos are laid out in a logical order, so that all the info makes sense...)

HF-DSC Comms
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX


Maritime HF Comms (in general)
https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y


Icom M-802 Instruction
https://www.youtube.com/playlist?lis...rC-8QKVyMb4tVr


Offshore Weather
https://www.youtube.com/playlist?lis...zdjTJjHlChruyY


Offshore Sailing
https://www.youtube.com/playlist?lis...KgTCj15iyl6qoY


VHF-DSC
https://www.youtube.com/playlist?lis...J6QugtO2epizxF



And, if you read the stickies right at the top of the Marine Electronics page, and read at least some of the links there in those stickies, you'll see how easy-peasy this is...

HF-SSB Radio, Proper Installation Tips/Techniques, etc.

Marine SSB Stuff (how-to better use / proeprly-install SSB, & troubleshoot RFI, etc.)



I hope this helps.

fair winds.

John
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Old 14-06-2019, 21:09   #10
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Re: Ssb dsc quandary

Quote:
Originally Posted by kcj View Post
A buddy and I have been reading/YouTubing up on ssb operations. We are about 800nm apart. This afternoon we were testing out the dsc function as per Annie Laurie’s direction. (Many thanks, very helpful) I was able to get one test to MNM on 4m to work... two hours later no go, figured it was time of day.

Any thoughts on what we are missing?

Many thanks in advance.
John

Individual HF DSC is always painful due to the regulations and the software design. There are two alternatives that are widely used.

ALE (Automatic Link Establishment) is a standard that allows alerting other HF stations and also exchanging link quality information. It is way smarter than DSC and it is all done in software. You need a program called PC-ALE, running on a PC connected to your radio and a ham license. It is a great system.

SelCall is another alert system. There are many iPhone/Android apps that generate and understand SelCall tones. All you need to do is to agree on a set of frequencies and SelCall IDs with your friend, configure the radio to scan these frequencies than set the phone to monitor the signal. When ready to call, the other station sends the IDs on each frequency until contact is made. A little clunky but very easy to setup and use among friends.

Good luck.
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Old 16-06-2019, 03:38   #11
kcj
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Re: Ssb dsc quandary

Update...

Making progress!
We both reprogrammed the scan and call frequencies on our m802s...

After reprogramming we can now both call each other using dsc, reply (with the units switching to traffic) BUT neither originating unit responds to the reply.

I have a dsc antenna, a 15’ wire that terminates at a thru deck fitting. My test dsc call to uscg on 4m works. My buddy does not have a secondary/dsc antenna.

Thoughts on why originating units do not reply to acknowledgement?

And thanks to all for the insights! ESP John for the kind offer😁 this is very helpful in moving us along the ssb learning curve...

Cheers
John
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