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Old 11-05-2014, 12:51   #16
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Re: Call on HF DSC....maybe.

It should be pointed out that in all this DSC talk, is that GMDSS procedure requires all distress alerts to be followed up by standard voice mayday calls. so you push the button AND you make a Mayday call.


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Old 11-05-2014, 15:40   #17
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Re: Call on HF DSC....maybe.

Dave,
1) Sorry about this but, Huh??
Quote:
Originally Posted by goboatingnow View Post
It should be pointed out that in all this DSC talk, is that GMDSS procedure requires all distress alerts to be followed up by standard voice mayday calls. so you push the button AND you make a Mayday call.
This was NOT part of my GMDSS class, and I have not seen this in the GMDSS rules...(and I've just spent a couple days rereading them!!!)
If this is a GMDSS rule, please post this rule...


I suspect however, that this is again another example of "procedure" that might be taught in the UK/EU, but is not actually part of the GMDSS???

And, I personally just spoke with a USCG radio officer who confirmed that if NO acknowledgment (ACK) is received from your DSC-Distress alerts (assuming they're sent out on multiple freqs), this isn't a bad idea, but certainly NOT part of the GMDSS requirements, as the GMDSS was designed to NOT have vessels "yelling Mayday all over the place" (his words), but rather to use the HF-DSC or EPIRB, and/or INMARSAT (again HIS words)....






2) Further, I re-read / researched on an old subject....
Your postings regarding the use of INMARSAT to fulfill ship-to-shore and shore-to-ship Sea Area A3 requirements and your comment that some vessels may have only an MF-DSC radiotelephone....


The facts are that the GMDSS requires (in addition to all the basic requirements and Sea Area A1 requirements), that all SOLAS vessels be equipped with:

From the SOLAS Reg. IV, 10.1, 10.2 and 10.3:
(and confirmed from the RTCM site this weekend)

For Sea Area A2:
a) --- a MF-DSC radiotelephone capable of transmitting and receiving on the frequencies 2187.5 kHz using DSC and 2182 kHz using SSB Voice.
AND
b) --- a DSC watchkeeping receiveroperating on 2187.5 kHz
AND
c) --- An HF radiotelephone capable of transmitting and receiving on all working frequencies in the maritime mobile service bands, from 1.6mhz - 27.5mhz, either on SSB Voice or SITOR (NBDP).
(This third requirement is normally fulfilled by the above MF radiotelephone, as most (all?) GMDSS MF transceivers also cover HF, and these MF/HF-DSC radiotelephones have DSC watch receivers maintaining a DSC watch on all six GMDSS DSC Freqs....although the "requirement" is for "2187.5 kHz, 8414.5 kHz and on at least one of the distress and safety DSC frequencies, such as 4207.5 kHz, 6312 kHz, 12577 kHz or 16804.5 kHz", in practice these radios usually maintain a DSC watch on all 6 DSC Freqs...)


Further, in addition to all of the above, for Sea Area A3:
EITHER:

a) --- An MF/HF-DSC radiotelephone, in addition to the above MF-DSC radiotelephone for Sea Area A2 requirements, capable of transmitting and receiving on all distress and safety frequencies in the maritime mobile service bands, from 1.6mhz - 27.5mhz, using DSC, SSB Voice and SITOR (NBDP).
AND
b) --- a DSC watchkeeping receiveroperating on 2187.5 kHz, 8414.5 kHz and on at least one of the distress and safety DSC frequencies, such as 4207.5 kHz, 6312 kHz, 12577 kHz or 16804.5 kHz.
AND
c) --- An HF radiotelephone capable of transmitting and receiving on all working frequencies in the maritime mobile service bands, from 1.6mhz - 27.5mhz, either on SSB Voice or SITOR (NBDP).
(Although this last requirement is usually fulfilled by the above mentioned Sea Area A2 required radiotelephone, meaning only two long-range MF/HF radiotelephones are typically used to fulfill this requirement)...

OR:

a) ---An INMRSAT-C station....
AND
b) --- An MF-DSC radiotelephone capable of transmitting and receiving on the frequencies 2187.5 kHz using DSC and 2182 kHz using SSB Voice.(can be the same one as required for Sea Area A2), or a non-DSC MF radiotelephone and a DSC watchkeeping receiver operating on 2187.5 kHz DSC.
AND
c) --- An HF radiotelephone capable of transmitting and receiving on all working frequencies in the maritime mobile service bands, from 1.6mhz - 27.5mhz, either on SSB Voice or SITOR (NBDP).
(usually this "HF radiotelephone" for SSB Voice and SITOR, is also an MF/HF-DSC radiotelephone, unless the vessel is an older one, whose owners are reusing old equipment in order to fulfill the minimum requirements...but these are typically NOT the ones spending the $$$ on INMARSAT terminals, etc...)


OR:

a) ---An INMRSAT-C station....
AND
b) --- An MF-DSC radiotelephone capable of transmitting and receiving on the frequencies 2187.5 kHz using DSC and 2182 kHz using SSB Voice.(can be the same one as required for Sea Area A2), or a non-DSC MF radiotelephone and a DSC watchkeeping receiver operating on 2187.5 kHz DSC.
AND
c) A second, separate/dedicated INMARSAT station, (or a separate/dedicated 406mmhz EPIRB used to initiate transmission of ship-to-shore distress alert from the position where the ship is normally navigated)



So, in the real world this adds up to the fact that even those vessels who have elected to fulfill their Sea Area A3 Shore-to-Ship and Ship-to-Shore communications requirements via INMARSAT, will still have at least an MF-DSC radiotelephone AND an HF-SSB radiotelephone (probably an MF/HF-DSC-SSB radiotelephone), for ship-to-ship communications....or in rare circumstances they'd have to have a second, dedicated INMARSAT system, along with the MF-DSC radiotelephone...


And, of course, for vessels compliant with Sea Area A4 requirements (whether they transit the high-latitude polar regions or not), they DO have full MF/HF-DSC capability....




3) Further "evidence" of the use of HF communications by commercial vessels at sea (both SOLAS and non-SOLAS) is the great majority of survey respondents who report regular/daily use of HF comms at sea....from the 2012 survey by the WMO/jcomm Joint WMO-IOC Technical Commission for Oceanography and Marine Meteorology....





4) Further, according to SOLAS Reg.IV, 15.7 and IMO Resolution A.702(17) and COM/Circ.117.)....
"On ships engaged on voyages in sea areas A3 and A4, availability of equipment shall be ensured by using a combination of at least two methods such as duplication of equipment, shore-based maintenance or at-sea electronic maintenance capability, as may be approved by the Administration, taking into account the recommendations of the Organization."
Not sure how many SOLAS vessels adhere to this rule....but it is interesting...




Sorry if I rambled on, but I spent some time confirming all the above by rereading the SOLAS regs / GMDSS rules, and wanted to be accurate...


Fair winds...

John
s/v Annie Laurie
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Old 11-05-2014, 17:34   #18
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Call on HF DSC....maybe.

John

I draw your attention to ITU -R M.541-9 Operational procedures for the use of digital selective-calling equipment in the maritime mobile service

In particular page 18 " Actions on receipt of a Distress alert in particular section 1.3
" in receipt of a DSC distress acknowledgement the ship in distress should commence the distress traffic by radiotelephony on the distress traffic frequency (2 182 kHz on MF, channel 16 on VHF) as follows:
– “MAYDAY”, etc .........( my etc )

In the CEPT standardised exam, there is no situation other then simple lack of time. Where any DSC alert of any nature is not followed by a voice procedure as is clearly laid out in the aforementioned ITU. Regulation


Furthermore in relation to ships satellite station , you are in full agreement with what I said

SOLAS IV regulations7-10. Allow either a HF solution or a Inmarsat ship satellite station ( which is not just Inmarsat C ) for sea area A3. There is therefore no requirement for mandatory HF installation for most trans-oceanic voyages with the exception of sea area A4.

For reference I draw your attention to IMO circular COMSAR circular 32 HARMONIZATION OF GMDSS REQUIREMENTS FOR RADIO INSTALLATIONS ON BOARD SOLAS SHIPS. In particular the chart on page 11 of the annex. It clearly shows A3 maybe solved by EITHER. A HF station or a INMARSAT Ships satellite station.

As you are aware GMDSS requires " two independant means of contacting the shore " in A1 this is solved by DSC VHF and EPIRB. in A2 this solved by DSC MF and EPIRB and in A3 by EITHER DSC HF or INMARSAT. Satelitte ships station. Only in sea area A4, which is not covered by Inmarsat is HF required.. No HF installation is required for A2. NOTE. National cartage requirements may mandate additional equipment. For example the USA. Has no sea area A2. Hence the discontinuation of MF alerting, hence many vessels have switched to MF/HF as these combined sets are common. However GMDSS can be satisfied by Inmarsat instead in A3.

As to usage. From talking in Europe certainly all shore comms are now sat based to my knowledge LYngby has no public correspondence facilities on HF. ( actually I forgot it no longer receives HF at all since 09 ) Hence simply listening to marine HF bands here will usually result in silence

Dave


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Old 11-05-2014, 20:34   #19
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Re: Call on HF DSC....maybe.

Yes, Dave I'm completely aware of the procedures to follow upon RECEIPT of a Distress Alert....
But that is NOT what we are talking about here....(we are talking about sending out an alert....and yes, it goes without saying that upon receipt of an ACK, you'd proceed with your distress traffic on the comparable Voice traffic frequency, and yes you would use the word MayDay....but that is NOT what we were discussing.....so, that's why I was puzzled by your posting)
Nor was this what you wrote earlier...

(And, I thought about what you wrote BEFORE I posted anything....thinking maybe you were just referring to the procedure after you're in receipt of a distress alert....but figured it was that 'ole UK/EU difference???)

Over here "in my neck of the woods", we just say "Sorry Buddy, I remembered wrong", or "oopss, I see where we were talking about 2 different things"...and there is no worries...
Perhaps you'd like to do that?? (you know, simply admit defeat...no worries here mate...)


And as for there not being anymore HF stations in NAVAREA III???
Huh???
As of the list I have from July 2013, there are 12 operational HF-DSC Coast Stations there, covering the Med / NAVAREA III....
Now, I admit that I do not have a list any more current than last July...but your mentioning of this "no more HF stations" seems quite odd to me...
(not to mention the great many MF-DSC coast stations)


Sorry gotta' go....just broke away to check my e-mail (more family things tonight)


John
s/v Annie Laurie

P.S. as for the rest....I think we are in agreement about the regs...but I think we disagree about what is actually installed / being used???
In EU/Med, you are saying vessels forgo an HF system altogether, and apparently have no concern about not having HF ship-ship voice / sitor comms???....(contrary to the regs over here)
But what I see here is that they DO have an HF system, and most have the full HF-DSC-SSB....
Perhaps there ARE variations in interpretations after all??
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Old 12-05-2014, 16:44   #20
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Call on HF DSC....maybe.

I'm not sure john what you are trying to prove.

I said that a DSC distress alert does not stand on its own , it's ITU procedure that it is followed up by a voice procedure. A DSC distress alert is in itself a procedure. You insist on counting angels on a pin. The point is that the ITU never saw DSC signalling as a system that stood alone. ( in fact there has been several discussions about removing DSC from HF, in the IMO,given all the issues that have generated., but the systems too far gone

Furthermore as to carriage requirements I do not believe there is any regional differences. I merely said that sea area 1,2,3 can be served by not installing HF. This is factually the case with the SOLAS 78 ( as amended) chapter IV regulations.

I didn't say per-say that HF isnt actually installed. One of the reasons HF is often installed is the redundancy of equipment requirements. For A3 this actually requires two complete independant Inmarsat satellite ships stations. A cost few boats want to bear. So the alternative is One Ships sat station and a HF unit.

What is clear in my experience is that ships are increasing using sat comms and not HF. Certainly in the sea areas. ( Northern Europe ) I'm involved. MF is still extensively used especially amongst the European fishing fleet.

Fundamentally with the dropping of HF public correspondence in Europe. Ship to HF station traffic dramatically fell, as ships have little or no reason to contact HF MRCC stations. ( and vice versa ) Ships business is know virtually exclusively carried out by sat comms. A scan of HF in Northern European waters brings up little traffic.

I used to be till recently a GOC GMDSS instructor and GMDSS examiner ( not at the same time )

In my view the next SOLAS and or ITU/WRCC amendments will give increasing importance to sat comms.

I'm not running down HF. After all I am a ham radio enthusiast. ( though little use lately ) nor am I saying that HF is not more popular elsewhere. But to me it's clear talking to ships captains, it's increasing regarded as unnecessary. Were the GMDSS regs modified to reduce the importance of HF. ( or allow a single sat station to suffice) , I would wager you would see a lot of installations being removed from ships.

Equally I can't see any form of TOR surviving the next review either.

Dave

Ps. When I meant no HF stations I should have been more specific. I meant no HF with public correspondence facilities. ( which is the reason ships sat stations are common now )


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