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Old 07-03-2014, 12:57   #46
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Re: Ham Radio vs Marine SSB

There are several issues with the "spectral purity" of ham transceivers. These include occupying or splattering outside the normal 2.7kHz width of a normal SSB signal, as well as suppression of harmonics.

In these respects, it is counter intuitive that some of the newer transceivers are the worst, i.e., they have a "dirtier" signal than some older ones. I believe the TS480SAT is an exception....it's reported to be pretty good. The extremely popular Icom IC-706 is one of the worst, though Icom has improved this in the later Mark II and, expecially, the MKIIG models.

Newer isn't necessarily better. And, there are plenty of ham radios which have both the frequency stability and well-suppressed spurious emissions to be judged as "clean".

To me, spectral purity is only one of several concerns in the ham radio vs. marine radio comparison. Of particular importance, IMHO, are:

  • ability to operate at lower voltages without FM-ing or cutting out
  • ease of operation for unpracticed crew members
  • legality (if anyone cares)
Bill
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Old 07-03-2014, 13:01   #47
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Re: Ham Radio vs Marine SSB

Sorry about the thread drift here!!!


socal,
I think you're missing the point here about BOTH MF/HF-DSC signaling, and MF/HF propagation....
Quote:
Originally Posted by socaldmax View Post
I understand that HF DSC sends a precoded distress message on multiple frequencies. The problem I have is with HF propagation.

Since HF bounces off of the ionosphere, there are going to be "rings" of areas where the signal bounced back down, and rings where the signal is not being received. So a vessel 75 mi away might not receive the signal, while a vessel 1,000 mi away might receive it.

I don't really think a vessel 200, 500 or 1,000 mi away is going to be able to render aid in a timely fashion. How far off course would a freighter go to render aid? That's assuming the vessel in distress is somewhere in front of the receiving vessel.
1) The 8mhz (8414.5khz) DSC signal will almost always have NO skip-zone daylight hours...so it will be received by all vessels and shore stations from 0 to as much as 1000 miles away daytime....(in actual real-world practice, taking into account your VHF range of 25-30 miles and the upper-usable range of 8mhz daytime of 600-800 miles, the 8414.5 DSC signal would most often be received by all vessels / shore stations from 25 - 600 miles away....

2) Nighttime there might be a "skip-zone" on 8mhz, from 100-300 miles or so...but that is why you can send a DSC call on any of the six int'l GMDSS DSC Distress and safety freqs.....and this is where a "six-freq" DSC call is very useful!!!

3) If you read the actual reports of Distress calls at sea, EPIRB activations, etc. as well as comments/recommends from the USCG and reps from COSPAS-SARSAT, you'll find that there is a GREAT advantage in signaling vessels in your area/region directly....
Even in the BEST possible scenarios, this can save 3 - 6 hours of waiting for help....and in most cases more....and in the worst cases, it will actually get you assistance when your EPIRB activation might NOT!!!

PLEASE read over these threads and PLEASE read over the links provided (especially the COSPAS-SARSAT and Cruising World links) and you'll learn a LOT about how these things work (and how they don't), how the GMDSS works, and real-world examples of what happens when the s*** hits the fan!!

SSCA Forum • View topic - EPIRB Activation? What happens/How to improve rescue odds

SSCA Forum • View topic - Icom M-802 DSC-Distress Signaling, what really happens!


After you read these threads and the links, you'll see that YES, a vessel a few hundred miles away from you may be the one to render assistance to you....and depending on WHERE you are at, that vessel 1000 miles away may be your only hope!!!


4) DSC-signaling is designed as a quasi-ALE system, which means it removes the "human element" and allows the radios to find the best overall freq for communications....
So, using a "six-freq" DSC-Distress message WILL get thru to just about everyone....including the vessels in your area/region (within 500 miles or so...)

And, don't forget that a container ship steaming at 20 - 24 kts, can make 500 - 600 miles in a day...




5) I'm going to look for a Youtube video that shows some amazing things from space!!!
But, until then, enjoy this one...






I hope this helps clarify things a bit...


Fair winds...

John
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Old 07-03-2014, 16:01   #48
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Re: Ham Radio vs Marine SSB

Chris,
Sorry if my "peeve" came off as a "rant"!!
It was NOT intended that way, I do sincerely apologize!!


But, the answers to your questions/concerns are:

Yes, unfortunately it does hold true for all HF ham radios....

And yes, I have seen the test results of the TS-480, both the 100-watt SAT..and the 200-watt HX (which has two of the 100-watt PA's combined), both the test data and scans done by Kenwood themselves and the indep. product review tests...and I'll provide all that data here for you...(see below)


But, First off a few pieces of news / facts...

1- There are NO current production HF ham transceivers, nor any made in the past 25-30 years, that even come close to the FCC Part 80 standard (nor the ITU standard) for transmit spectral purity and transmit IMD products....
(the one "exception" is the 5-watt portable FT-817, equipped with the TCXO-9 Option. Compliant ONLY at 5 watts output or less...)
Sorry, but those are the facts....

See the listing here...
https://comm.capnhq.gov/equipment/hf...ent.cfm?type=a
https://comm.capnhq.gov/equipment/HF_List.cfm
https://comm.capnhq.gov/equipment/hf...cfm?rec_id=170


2- There are a rare few older (Collins, Drake, etc. from the late 60's thru late 70's) ham transceivers that DO pass the Part 80 spectral purity and IMD specs, but fail the freq stability specs...
It is the "modern" HF ham transceivers (those made in the past 25-30 years to present day 2014), that are the worst performers!!
Again, sorry....but those are the facts...


3 - Although, here is some good news....
The Kenwood TS-480 (SAT or HX) is actually fairly good in this regard, when compared to other modern HF ham transceivers, as Kenwood actually designed the radio to really BE pretty good in spectral purity as their goal was to make a 200-watt unit (which they did by combining two of the 100-watt PA's in one chassis), and they needed to make the transmitter pretty clean....
And they also did a good job in designing a non-alc-based speech processor / speech compressor circuit (and in this area, the 480 is an almost singularly unique modern ham transceivers....)


4 - So, taking into account the above facts....IF you had to operate any modern HF ham transceiver on the marine freqs, the TS-480 is one of the better choices....to be clear it does NOT come close to meeting the specs, missing the spectral purity spec by 10db on the SAT/100-watt model and by 16db on the HX/200-watt model), but it does a better job than most other modern ham transceiver (and this is probably why your friends recommended it...) And, it requires the optional SO-3 TCXO, in order to have decent freq stability....

(The 480SAT at 100-watts, is 13 db worse than the M-802 in spectral purity....and 25db worse than the M-700Pro..and these radios have 50 watts/2db more transmit power...at a lower power level the differences are even greater...but operating the HX-200-watt unit at 100-watts would probably get very close to passing, maybe even compliant???
If you look at the other threads I referenced above you'll see more details...)




5) Now, as for the exact specs....remember that these tests (and the specs derived from them) are all done at 13.8vdc at the radio.....something that is NOT likely to happen much on a cruising boat....and certainly not on the early morning nets when batteries have been draining all night, etc...
And, understand that the transmit IMD specs get significantly worse as the PA voltage decreases...
(Further, the "marine transceivers" must meet the spec/standard at all voltages within their voltage spec.....which for the M-802, etc. is 13.6vdc +/- 15%...which is 11.5vdc to 15.6vdc...)



Directly from Kenwood, the TS-480's transmit IMD figures are:
-26 db from PEP = 3rd...
-39 db from PEP = 5th...
-50 db from PEP = 7th...
-50 db from PEP = 9th...
with higher orders down a little bit more...



I can't get the spectral scans to load up (they're old scans)....but the above IMD specs ARE accurate, and the TS-480 scan looks more like the IC-718 or IC-706 scans (although not as bad) than it does the M-802 or M-700Pro scans...
(Again to be clear, the TS-480 is one of the better modern HF ham transceivers in regard to spectral purity and transmit IMD products...but it doesn't come close to what actual Part 80 "type certified" Marine HF transceivers spec out as....)

Here is a page that shows some radios 3rd and 5th specs...
http://funkperlen.files.wordpress.co.../11/tx-imd.pdf

Quote:
Originally Posted by witzgall View Post
While I believe that this is true for some radios, especially older designs, I don't think this holds true for all ham radios. Have you tested a Kenwood 480 for these issues? If not, how can you use a blanket statement to describe it's performance? I fully understand what the FCC rule is there for, but a rule does not make a radio bad.

Before I took off cruising, I spoke to several life-long hams, guys who were radio and communication engineers by trade, about this very issue. They both agreed that while they had not done any specific testing on the TS-480 radios (one had one in their shack/repeater/emergency comms center at their place of work), they felt confident that it would not be an issue with that specific radio.
So, Chris as for which HF ham transceiver is the best choice should you find it necessary to violate the rules and use it on the marine bands, I fully understand the recommendation from those "life-long hams" / "guys who were radio and communications engineers" (FYI, BOTH of these describe me as well...), but please understand that does not mean the 480 actually is as good as a real HF marine transceiver (it isn't), nor does it make the use of it on the marine bands a good thing (in my opinion, it is not)...

Now, I won't scold you on this....nor try to convince you to stop violating rules, etc...
I'm not that kind of guy....
rather I'm pretty easy-going and understandable guy....and I suspect that your radio isn't causing much of an issue for anyone...


But the facts are the facts...and the oft repeated myth that "modern ham radios are as good as a marine radio" IS A MYTH....
And, no matter who tells 'ya different, most of the test data and compliance data and specs are public documents and much is available on-line from official sources (such as the US Gov't, etc.), for free....

Now "back-in-the-day" 30+ years ago, when marine HF radios were relatively expensive compared to HF ham radios....and when the spectral purity of the ham transceivers was significantly better than in recent days....and when the transmitter test data was not available at everyone's finger tips (no internet back then, ya' know).....I can understand the myth spreading....
But nowadays, I fear it is just for commercial/economic reasons....(or just too many folks are afraid to stand up and say that "The Emperor Has No Clothes!" ????)

So everyone can believe what they wish...I will not try and convince anyone of anything...
I'll just provide the facts and resources, and some insight into how/why the myths get promoted...
What anyone wants to do with these facts (and insights) is up to them...
No worries here...





EDIT....
Just saw Bill's last post, and I wanted to say I agree with this 100%....
Quote:
Originally Posted by btrayfors View Post
To me, spectral purity is only one of several concerns in the ham radio vs. marine radio comparison. Of particular importance, IMHO, are:

  • ability to operate at lower voltages without FM-ing or cutting out
  • ease of operation for unpracticed crew members
  • legality (if anyone cares)
Bill

WA6CCA






I hope this clears things up....
Fair winds.

John
s/v Annie Laurie
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Old 07-03-2014, 18:34   #49
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Re: Ham Radio vs Marine SSB

Ham radio is designed for land-based applications; if it stops working you might have leave the shack and spend some time with your family.
Marine radio, on the other hand, is designed to work AT SEA, its primary function being preservation of life. If it stops working when it is supposed to work you will not spend any more time with your family.
POINT IS: Darwinism at play here, if you have the money to buy a boat you should install a proper radio system.
Proper radio setup: HF DSC with two antennas, AIS transmitter, VHF DSC, Two dedicated handhelds, Two EPIRBS, 2 SARTs. Will cost you around 6 large, seeing that most readers have 150,000 dollar plus yachts here is it that much to ask? I'd get a Sat-C terminal and sat phone for 2-3 grand extra, Sat C is brilliant for weater reports and really quick with SAR coordination.

Ham gear (with a licence, get a licence it is minimal studying) is a good BACKUP. It is NOT equivalent with pro marine gear, otherwise it 1) would be certified 2) pro gear wold not cost 6x as much.
And please, if you can, have a look at power options for life-saving raidio equipment, HF and VHF gear must be on a totally isolated battery bank with enough juice for at least 72 hours of operation.

I noticed one member posting an image of "this is my comms station" type, congratulations, you've just put all your eggs in one basket. Get a fire in the vicinity and all your gear is GONE. Ooops. Let me guess: connections and cabling is not fireproof, items are not separated, and you have no smoke alarm dedicated to electronics.

If you have the space, Emergency Comms should be in a totally separate location with their own battery banks. Antennas disconnected and grounded in port, so leave the boat and lighting will not fry gear.
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Old 07-03-2014, 19:25   #50
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Re: Ham Radio vs Marine SSB

SDR,

Just as a matter of interest... do you wear a PFD in the bathtub?

That is PROPER bathing attire, for slips and subsequent drownings in the bath are known causes of death.

I agree that your proposed proper radio system is a bonzer setup, but frankly, I can't agree that the degree of sustainability and redundancy is necessary for even us who do cross oceans. Perhaps for extreme high latitude applications, but for normal cruising, well, it seems over the top to me.

And I doubt if Darwin is concerned with me, for I am well past the age for reproduction!

Cheers,

Jim (first ham license in 1950)
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Old 07-03-2014, 19:39   #51
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Re: Ham Radio vs Marine SSB

Quote:
Originally Posted by Jim Cate View Post
SDR,

Just as a matter of interest... do you wear a PFD in the bathtub?
Wetsuit in the pool, SO loves it

No offence, but the lax attitude towards safety is generally really bad with cruisers. Thought the above setup described should be compulsory, I cannot fathom the reason why most can not afford it?
It is in your interest to be found - ask the couple who spent 6 months in a liferaft.
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Old 07-03-2014, 19:43   #52
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Re: Ham Radio vs Marine SSB

Quote:
Originally Posted by sdrformariners View Post
Wetsuit in the pool, SO loves it



No offence, but the lax attitude towards safety is generally really bad with cruisers. Thought the above setup described should be compulsory, I cannot fathom the reason why most can not afford it?

It is in your interest to be found - ask the couple who spent 6 months in a liferaft.

The simple reason is the vast vast majority of cruisers don't get into trouble and don't need rescuing. Hence the reason none of this is compulsory.

I would further suggest 6 k is way of , 15k more likely , a new ham setup or marine SSB is about 4k on its own.

Your list is a good suggestion. But pure fantasy.

Dave


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Old 07-03-2014, 20:22   #53
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Re: Ham Radio vs Marine SSB

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Originally Posted by goboatingnow View Post
But pure fantasy.
This would be a minimum setup carried by an ocean-crossing merchant vessel.

Prices (off ebay):
Icom IC 802 2000,
EPIRB: 300 each
SART: 300
DSC VHF: 300
AIS: 800
Backup handhelds: 50 each

Even for an ocean-crossing vessel AIS+VHF+Epirb+Sart can be had for around 2 grand, so even if you have no HF link and you go missing, people will know your last approx position (off AIS) so that narrows down the seach and rescue area.

I'll stop being offtopic, or the mods can move this under a new thread, but it is really infuriates me when the attitude is "we know what we're doing, we don't get into trouble and we don't need proper safety ahh no, i buy some new sails so I can go 6.0 instead of 5.8 knots".
Or the new touch-screen plotter instead of an AIS transponder.
This is mostly true to marina queens. I met a single-hander in Veracruz, 30 foot wooden boat, AIS trasponder plus Epirb plus SART handy, " I want to see ships know where I am"

Cheers,

Akos
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Old 07-03-2014, 20:51   #54
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Re: Ham Radio vs Marine SSB

Quote:
Originally Posted by sdrformariners View Post
Ham radio is designed for land-based applications; if it stops working you might have leave the shack and spend some time with your family.
Marine radio, on the other hand, is designed to work AT SEA, its primary function being preservation of life. If it stops working when it is supposed to work you will not spend any more time with your family.
POINT IS: Darwinism at play here, if you have the money to buy a boat you should install a proper radio system.
Proper radio setup: HF DSC with two antennas, AIS transmitter, VHF DSC, Two dedicated handhelds, Two EPIRBS, 2 SARTs. Will cost you around 6 large, seeing that most readers have 150,000 dollar plus yachts here is it that much to ask? I'd get a Sat-C terminal and sat phone for 2-3 grand extra, Sat C is brilliant for weater reports and really quick with SAR coordination.

Ham gear (with a licence, get a licence it is minimal studying) is a good BACKUP. It is NOT equivalent with pro marine gear, otherwise it 1) would be certified 2) pro gear wold not cost 6x as much.
And please, if you can, have a look at power options for life-saving raidio equipment, HF and VHF gear must be on a totally isolated battery bank with enough juice for at least 72 hours of operation.

I noticed one member posting an image of "this is my comms station" type, congratulations, you've just put all your eggs in one basket. Get a fire in the vicinity and all your gear is GONE. Ooops. Let me guess: connections and cabling is not fireproof, items are not separated, and you have no smoke alarm dedicated to electronics.

If you have the space, Emergency Comms should be in a totally separate location with their own battery banks. Antennas disconnected and grounded in port, so leave the boat and lighting will not fry gear.

I agree with your approach to safety, plenty of levels of redundancy and isolation between systems just in case multiple issues come up.

I'm just not on board with all of the assumptions you're making. Just because a guy posted a pic of a very well equipped nav station, you're assuming that is all of his gear. There is a good possibility that he feels exactly as you do, and there's more gear in a different location, on a different battery bank.

Just because someone posts something doesn't mean they revealed everything pertinent or everything they know, they might have kept it short for brevity or to minimize thread drift, which seems to be frowned upon around here.
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Old 07-03-2014, 20:58   #55
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Re: Ham Radio vs Marine SSB

Quote:
Originally Posted by ka4wja View Post
Chris,
Sorry if my "peeve" came off as a "rant"!!
It was NOT intended that way, I do sincerely apologize!!


But, the answers to your questions/concerns are:

Yes, unfortunately it does hold true for all HF ham radios....

And yes, I have seen the test results of the TS-480, both the 100-watt SAT..and the 200-watt HX (which has two of the 100-watt PA's combined), both the test data and scans done by Kenwood themselves and the indep. product review tests...and I'll provide all that data here for you...(see below)


But, First off a few pieces of news / facts...

1- There are NO current production HF ham transceivers, nor any made in the past 25-30 years, that even come close to the FCC Part 80 standard (nor the ITU standard) for transmit spectral purity and transmit IMD products....
(the one "exception" is the 5-watt portable FT-817, equipped with the TCXO-9 Option. Compliant ONLY at 5 watts output or less...)
Sorry, but those are the facts....

See the listing here...
https://comm.capnhq.gov/equipment/hf...ent.cfm?type=a
https://comm.capnhq.gov/equipment/HF_List.cfm
https://comm.capnhq.gov/equipment/hf...cfm?rec_id=170


2- There are a rare few older (Collins, Drake, etc. from the late 60's thru late 70's) ham transceivers that DO pass the Part 80 spectral purity and IMD specs, but fail the freq stability specs...
It is the "modern" HF ham transceivers (those made in the past 25-30 years to present day 2014), that are the worst performers!!
Again, sorry....but those are the facts...


3 - Although, here is some good news....
The Kenwood TS-480 (SAT or HX) is actually fairly good in this regard, when compared to other modern HF ham transceivers, as Kenwood actually designed the radio to really BE pretty good in spectral purity as their goal was to make a 200-watt unit (which they did by combining two of the 100-watt PA's in one chassis), and they needed to make the transmitter pretty clean....
And they also did a good job in designing a non-alc-based speech processor / speech compressor circuit (and in this area, the 480 is an almost singularly unique modern ham transceivers....)


4 - So, taking into account the above facts....IF you had to operate any modern HF ham transceiver on the marine freqs, the TS-480 is one of the better choices....to be clear it does NOT come close to meeting the specs, missing the spectral purity spec by 10db on the SAT/100-watt model and by 16db on the HX/200-watt model), but it does a better job than most other modern ham transceiver (and this is probably why your friends recommended it...) And, it requires the optional SO-3 TCXO, in order to have decent freq stability....

(The 480SAT at 100-watts, is 13 db worse than the M-802 in spectral purity....and 25db worse than the M-700Pro..and these radios have 50 watts/2db more transmit power...at a lower power level the differences are even greater...but operating the HX-200-watt unit at 100-watts would probably get very close to passing, maybe even compliant???
If you look at the other threads I referenced above you'll see more details...)




5) Now, as for the exact specs....remember that these tests (and the specs derived from them) are all done at 13.8vdc at the radio.....something that is NOT likely to happen much on a cruising boat....and certainly not on the early morning nets when batteries have been draining all night, etc...
And, understand that the transmit IMD specs get significantly worse as the PA voltage decreases...
(Further, the "marine transceivers" must meet the spec/standard at all voltages within their voltage spec.....which for the M-802, etc. is 13.6vdc +/- 15%...which is 11.5vdc to 15.6vdc...)



Directly from Kenwood, the TS-480's transmit IMD figures are:
-26 db from PEP = 3rd...
-39 db from PEP = 5th...
-50 db from PEP = 7th...
-50 db from PEP = 9th...
with higher orders down a little bit more...



I can't get the spectral scans to load up (they're old scans)....but the above IMD specs ARE accurate, and the TS-480 scan looks more like the IC-718 or IC-706 scans (although not as bad) than it does the M-802 or M-700Pro scans...
(Again to be clear, the TS-480 is one of the better modern HF ham transceivers in regard to spectral purity and transmit IMD products...but it doesn't come close to what actual Part 80 "type certified" Marine HF transceivers spec out as....)

Here is a page that shows some radios 3rd and 5th specs...
http://funkperlen.files.wordpress.co.../11/tx-imd.pdf

So, Chris as for which HF ham transceiver is the best choice should you find it necessary to violate the rules and use it on the marine bands, I fully understand the recommendation from those "life-long hams" / "guys who were radio and communications engineers" (FYI, BOTH of these describe me as well...), but please understand that does not mean the 480 actually is as good as a real HF marine transceiver (it isn't), nor does it make the use of it on the marine bands a good thing (in my opinion, it is not)...

Now, I won't scold you on this....nor try to convince you to stop violating rules, etc...
I'm not that kind of guy....
rather I'm pretty easy-going and understandable guy....and I suspect that your radio isn't causing much of an issue for anyone...


But the facts are the facts...and the oft repeated myth that "modern ham radios are as good as a marine radio" IS A MYTH....
And, no matter who tells 'ya different, most of the test data and compliance data and specs are public documents and much is available on-line from official sources (such as the US Gov't, etc.), for free....

Now "back-in-the-day" 30+ years ago, when marine HF radios were relatively expensive compared to HF ham radios....and when the spectral purity of the ham transceivers was significantly better than in recent days....and when the transmitter test data was not available at everyone's finger tips (no internet back then, ya' know).....I can understand the myth spreading....
But nowadays, I fear it is just for commercial/economic reasons....(or just too many folks are afraid to stand up and say that "The Emperor Has No Clothes!" ????)

So everyone can believe what they wish...I will not try and convince anyone of anything...
I'll just provide the facts and resources, and some insight into how/why the myths get promoted...
What anyone wants to do with these facts (and insights) is up to them...
No worries here...





EDIT....
Just saw Bill's last post, and I wanted to say I agree with this 100%....








I hope this clears things up....
Fair winds.

John
s/v Annie Laurie


John, thanks for all of the great info! I learned a lot today! I really had no idea how bad the harmonics were on the ham radios!

I will definitely get an M802 when the time comes (if it's not already installed) and will probably keep my IC-7200 I just bought for ham use. Just out of curiosity, how bad is the spectral purity of the IC-7200? A few hams at the local HRO steered me toward the unit, citing that it was a good one for the money, but we never specifically discussed that parameter.
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Old 07-03-2014, 21:31   #56
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Re: Ham Radio vs Marine SSB

Gday Akos aka sdrformariners,
I must say you present a more minimalist approach here... Software Defined Radio for Mariners
That is a site I quite enjoy.
El Ping ( first dog licence in 1957)
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Old 08-03-2014, 08:22   #57
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Re: Ham Radio vs Marine SSB

Quote:
Originally Posted by sdrformariners View Post
Wetsuit in the pool, SO loves it

No offence, but the lax attitude towards safety is generally really bad with cruisers. Thought the above setup described should be compulsory, I cannot fathom the reason why most can not afford it?
It is in your interest to be found - ask the couple who spent 6 months in a liferaft.
I would be very interested to read about the couple that spent six months in a life raft. The couple I a familiar with that spent the longest time in a raft was Maurice and Maralyn Bailey who were rescued after 117 days.

Respectfully I have to disagree that the lack of a large suite of electronics demonstrates a lax attitude towards safety. Basic safety on a boat starts with a well found vessel and well prepared crew. After that, proper planning, weather tracking, on board safety gear like harnesses and jack lines, life raft etc.

It is a fact of life that most cruisers have to deal with budget constraints and space limitations on their vessel. There are cruisers sailing boats that cost less than the electronics package you suggest as compulsory which by the way I think would cost a good bit more than you estimate.

There are some on this forum with unlimited resources but for the rest of us it has to come down to a decision on where best to spend our limited dollars (or Euros or Pounds or Rand or whatever) and the electronics you suggest would be out of the budget. Better to spend more on other gear that is more essential than electronics which, with limited exceptions, are useful mainly to get rescued and not helpful at all in keeping the boat and crew safe in the first place.
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Old 08-03-2014, 08:57   #58
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Re: Ham Radio vs Marine SSB

Saw this video yesterday. What struck me was:

100 miles off coast
No one raised VHF
No one raised SSB
Only the HAM radio worked
Abandoned boat in Gulf of Mexico - YouTube
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Old 08-03-2014, 09:57   #59
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Re: Ham Radio vs Marine SSB

Salty,
Yes, there is usually someone on 14.300mhz, as long as the band is open (but that is NOT always the case)...

BUT...
But, the reason that this guy could NOT raise anyone on ch. 16 VHF , nor 2182khz MF, is NOT because the maritime bands are not useful or monitored (they ARE), but is because NOBODY is actually monitoring 2182khz, nor ch. 16....vessels at sea have NOT been required to do so for over 15 years!! (since Jan 1999).

I'm at a client's office and cannot listen to the video, but reading the text on the screen it appears that he never actually attempted to raise anyone on DSC???
Nor, did he attempt to use one of the GMDSS HF VOICE Distress / Calling frequencies??? (4125khz, 6215khz, 8291khz, 12290khz, or 16420khz)
Quote:
Originally Posted by SaltyMonkey View Post
Saw this video yesterday. What struck me was:

100 miles off coast
No one raised VHF
No one raised SSB
Only the HAM radio worked
Abandoned boat in Gulf of Mexico - YouTube
If you actually read the GMDSS rules that have been in effect since Jan 1999 (that's over 15 years now), you'll see that 2182khz is NOT what you need to use...
And, even for years before that, most commercial vessels had a "2182 watch receiver" which did NOT listen for a voice Mayday, but rather sat silent on the bridge of the ship, listening for the two-tone "alarm" (sounds like an old European or UK police siren) that all was produced by the "alarm generator" that commercial vessel's MF transmitters had built-in....
This means that for more than 25 years, using 2182khz to yell for help was of almost NO value at all (unless you just so happen to be within a 100 miles of a USCG station, in years past...but now even they don't monitor 2182!!!)

Please have a look at these threads, where you'll learn a lot....(and watch / listen to THESE videos as well, where you'll learn a LOT)...

USCG to Discontinue ONLY 2mhz Distress Watchkeeping 8-1-2013

Icom M-802 DSC-Distress Signaling, what really happens!

EPIRB Activation? What happens/How to improve rescue odds


Icom M-802 Instr Videos(basic-adv) & LIVE DSC-Distress Call
http://www.cruisersforum.com/forums/f13/icom-m-802-instr-videos-basic-adv-and-live-dsc-distress-call-114734.html


And, while most commercial vessels at sea will monitor VHF Ch. 13 Voice (for Bridge-to-Bridge comms), they are unlikely to have the volume turned up on Ch. 16, or not be monitoring Ch. 16 at all!!!
BUT...
But, they ARE required to monitor VHF-DSC, as well as MF/HF-DSC, continuously!!!!

Those ARE the facts and have been for the past 15-25 years!!!
Like it or not, that's what DSC is for!!!

So, if the mariner in the video had a VHF-DSC radio, he surely would've raised any vessel in his local vicinity (any within VHF range)....and if he had an HF-DSC radio (such as the M-802), he surely would have raised the USCG as well as many (100's probably) of vessels in his region...ALL within 30 seconds, and all would have his exact GPS location and his radio would be all set to speak with them directly, on the best channel available....all automatically!!!

Now, even if he didn't have either a VHF-DSC radio, nor an HF-DSC radio, he still could've raised the USCG on 8291khz or 12290khz (both of which would have easily gotten him in direct contact with the USCG within a few seconds!)
Quote:
Effective Jan 01, 2005 U.S. Coast Guard long range communications stations NMF, NMN, NMA, NMG, NMC, NMO, NOJ and NRV changed their single sideband voice radio guard to the following simplex frequencies: 4125, 6215, 8291, and 12290 kHz. These frequencies are intended for initial voice contact and distress alerts and working only. Follow-on working frequencies if necessary shall be by mutual agreement after initial contact
It just goes to show you that no matter how much the GMDSS is praised and publicized by commercial mariner worldwide, I can't even get the main stream US-based sailing media to accept that it IS here, and it DOES work, and works VERY well!!!

~~~~~


This incident is further evidence of the lack of understanding of DSC and the GMDSS....which has been a peeve of mine for 10 years now...

Here is a true story...
A peeve of mine, from about 3 years ago, "Cruising World" published an article about a guy's ordeal / rescue ona return trip from Bermuda back to the US....where he also tried 2182khz, in the middle of the day about halfway between Bermuda and the US, and got no response....so he fiddled with his sat phone for a while and finally got thru to the USCG by phone....
he made NO mention in his article about his own failure to understand that 2182khz was the WRONG frequency to use, nor his own failure to know what freqs to actually use (4125khz, 6215khz, 8291khz, 12290khz.....but most likely 8291khz or 12290khz daytime!!!)....
Nor did he even mention anything at all about the GMDSS or HF-DSC!!!
(I suppose the public embarrassment would've been too much for him??)
BUT...
But, the REAL injustice here was that not only did "Cruising World" pay him for hi article, they also included an editor's "sidebar" with information about programming the relevant RCC's phone numbers into your handheld sat phone should you ever be venturing offshore....
And, they made NO mention of DSC, HF-DSC, nor the GMDSS....none at all!!!

I wrote them a stern letter-to-the-editor....but received NO response, nor did my letter ever appear in their glossy magazine....

So, when we have supposed journalists making grave errors in reporting / editing, that can cause someone their lives....I'm not surprised that most of my postings here (and on the SSCA disc boards) regarding HF-DSC signaling and understanding of the GMDSS, all seem to fall on deaf ears!!!


~~~~~~~~~~~~


Here in red is just some opinion...
It just seems to me (my opinion here) that since all the details of this (DSC and the entire GMDSS) was announced OVER 20 YEARS AGO, and it all became effective over 15 years ago, that we sailors/cruisers/voyagers should ALL know about it all by now!!!
Shouldn't we???

~~~~~~~~~~~~~


Gotta' go....

Fair winds..

John
s/v Annie Laurie
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Old 08-03-2014, 10:06   #60
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Re: Ham Radio vs Marine SSB

The primary reason john is the lack of certified radio training in the US. There is simply no route available to get the practical understanding of the GMDSS to us VHF users

Dave
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