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Old 03-07-2020, 03:25   #76
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Re: AIS through satellites.

You are back via Sat! One hour ago... 2054 SA time... abeam the old Ballast Head jetty
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Old 03-07-2020, 04:29   #77
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Re: AIS through satellites.

Meanwhile back in the west a few minutes ago...
Tantabiddi via Albany Base Station on the left... the small icon.... 17 minutes old
Tantabiddi via satellite on the right... big icon....8 minutes old...
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Old 03-07-2020, 05:27   #78
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Re: AIS through satellites.

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Originally Posted by El Pinguino View Post
You are back via Sat! One hour ago... 2054 SA time... abeam the old Ballast Head jetty
Thank you for spottong that, I would have missed it and I would have remained worried!
It can't be coincidence. We appeared on satellite within minutes of leaving American River. It must be Ballast Head obscuring the signal.
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Old 03-07-2020, 05:35   #79
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Re: AIS through satellites.

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Originally Posted by El Pinguino View Post
Meanwhile back in the west a few minutes ago...

Tantabiddi via Albany Base Station on the left... the small icon.... 17 minutes old

Tantabiddi via satellite on the right... big icon....8 minutes old...


Well, we wonít do the same. We stopped to sleep for two hours, playing a juggling act on the tides. I didnít want to do the channel at low tide, and I wanted cross Backstairs at slack water, thanks to a reminder from VMR American River. So we turned to starboard within moments of that satellite fix and anchored off Baudlin Beach for a snooze.

Takes a bit of resolve to climb out from under the doona in this sort of weather, as I am sure youíd know better than most.
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Old 03-07-2020, 14:45   #80
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Re: AIS through satellites.

At 0643 local time this morning, I sent you an e-mail. You had a 2 min. old position that I saw, too. I figured it was a shore station that had you, rather than via satellite, but I really don't know how to tell.

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Old 03-07-2020, 15:07   #81
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Re: AIS through satellites.

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At 0643 local time this morning, I sent you an e-mail. You had a 2 min. old position that I saw, too. I figured it was a shore station that had you, rather than via satellite, but I really don't know how to tell.

Ann
Good morning Ann,
Unless you are paying about $US3500 a year in subs the sat derived positions only show ship type, age of position, and no other details.

Land based go into the details ( click on the ship of interest ) and second line from the bottom it will show what shore station the report is coming through. Click on that and you get all the station details.... in this case 3635 WirrinaSRS.

Position is now a bit old... could be the range or the shore station may be offline.
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Old 03-07-2020, 15:36   #82
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Re: AIS through satellites.

Weíve sailed out of range of Wirrina and are now covered by Hallet Cove. Only 23 miles to go.Click image for larger version

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Old 03-07-2020, 15:37   #83
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Re: AIS through satellites.

Iím going to finish my tea then launch the asym, the wind has dropped.
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Old 05-07-2020, 16:29   #84
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Re: AIS through satellites.

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Now to antennas. go to this page

Quadrifilar helicoidal antenna - Javascript on-line calculator
and work on 162 Mhz


This will get your signal up there and to ships. The radiation diagram will almost be spherical.
If your antenna is mounted on your stern rail, you just bend it a good 45-90 degrees and you hit the birds with your 3dB amplified signal. It should put you on the chart, but you have to bend it back.

My strategy is to stay on a cheapish CSTDMA unit as SOTDMA (B+) doesn't help sailing boats much (same transmit frequency as CSTDMA below 14kts) and invest in a good coax and fittings(!): RG58 will quickly halve your output compared to the good old rg213.
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Old 05-07-2020, 16:51   #85
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Re: AIS through satellites.

One good thing about AIS data being received by satellites is that this is how Search and Rescue co-ordination stations identify vessels in the area of a search. Thus they can redirect mership traffic to a SAR situation in their area of operations. Luckily they are willing to pay the subscription fees. At least in the case of Australia. Which does have a rather large area of responsibility, particularly considering their population.
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Old 08-07-2020, 12:24   #86
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Re: AIS through satellites.

Watching a friend ours transit the BC inner passage via AIS..some what interesting that AIS via sat. sees much more coverage up there than along the US East Coast..
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Old 09-07-2020, 14:01   #87
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Re: AIS through satellites.

David,
This isn't really accurate....
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One good thing about AIS data being received by satellites is that this is how Search and Rescue co-ordination stations identify vessels in the area of a search. Thus they can redirect mership traffic to a SAR situation in their area of operations. Luckily they are willing to pay the subscription fees. At least in the case of Australia. Which does have a rather large area of responsibility, particularly considering their population.
No worries about the confusion, most sailors have never heard of AMVER, as it is one of those little talked-of services that is oh so very important to the lives of those that ply the oceans of our planet!
Perhaps I can clarify things for you, and everyone here?

So, David, et al,
Please understand that I'm not intending for this to be a drifting / off-topic post, nor a long-winded explanation of Search And Rescue (SAR), AMVER, etc., but thought some here might want to have some further info?

Maybe? Maybe not? Oh well, here goes anyway!


{Fyi, my first use of AIS on-board was in 2006 with standalone receive-only AIS....followed a few years later with an Emtrak Class B AIS transponder and Vesper Watchmate display (and also AIS NMEA0183 38400baud data to both my chartplotters/MFD's)...so, I've used both receive-only and Class B transponders, offshore, across the Atlantic, as well as coastally...but have never had a need to be "tracked", nor have I cared if I was....although, if I was transiting areas of high piracy, I would care, and be sure to switch my transponder to "silent" mode...}



While, I of course do see Satellite-AIS to be a nice advancement that has come over the past few years, and there may be some RCC's that use this data to better direct their messages to vessels when implementing a SAR response, just remember this is not SOP for most....as it's AMVER that's been the way this has worked for decades...



So, maybe I should just spend a couple minutes reminding us all about AMVER (and VOS)...


AMVER was established by the USCG in 1958, for use by all / everyone worldwide, for free, all nations are welcome, and all merchant, fishing, towing, etc. vessels are welcome (even pleasure boats can participate!)....and while there are a few entities that don't like providing their ships' voyaging data to the United States, most do!
This is a worldwide system, that works! And, has worked for many decades, helping save the lives of 10's of thousands of mariners, crew and passengers, over the years....and costs my fellow US taxpayers less than one penny (less than $0.01) each, per year!

https://www.amver.com/

https://www.amver.com/Content/Docs/Facts/UscgCgMixAmverFactSheet.pdf

http://www.professionalmariner.com/May-2019/Six-decades-later-AMVER-still-lifesaver-for-mariners-in-distress/

https://www.marineinsight.com/marine-navigation/what-is-automated-mutual-assistance-vessel-rescue-system-amver/



FYI, AMVER is required for all US-flagged SOLAS vessels, and all US-flagged merchant and towing vessels making voyages of more than 24 hours....but, of course is voluntary for everyone else.
Although the IMO does have AMVER included in their rules and procedures, here is a quote from the IMO: “AMVER provides important vessel position information to rescue coordination centers in the form of search-and-rescue surface plot pictures to aid in the rescue or assistance of mariners in distress,” said Heike Deggim, director of the IMO’s Maritime Safety Division. “Over the years, AMVER-participating merchant ships have rescued or otherwise assisted more than 15,000 persons, so this is very much appreciated by IMO and the entire seafarers’ community.”



There are 121 nations, with approx. 20,000 registered vessels, now participating in AMVER....and with > 7000 ships at sea being tracked by AMVER at any particular moment (in 2018, the daily average was 7260 ships tracked at sea each day), this is what allows most rescues at sea to actually occur....


{remember that once outside of USCG helo range, and/or beyond the coast guard range of even many first world nations, most rescues at sea are undertook by merchant vessels (mostly SOLAS-grade vessels), and these are the ones tracked by AMVER...}


AMVER participating vessels send their sail plan, as well as departure and arrival reports, to AMVER, so they know their route before leaving port, and although they are required to update their position at least every 48hrs (and the AMVER computers DR every vessels' position between position fix updates), most update their position every 6 hours automatically (some every 3 hours), thru their GMDSS consoles / equipment, and/or their VOS weather reporting software...


[remember the "A" in AMVER stands for "Automated"]


So, an AMVER surpic (Surface Picture) knows where everyone of these ships are, at all times....and all this data is instantly provided to all RCC's 24/7/365, whenever a SAR is needed!


And, AMVER also has the direct satellite phone number of the ship's bridge, their INMARSAT-C terminal number, direct email, (as well as their MMSI # and radio callsign), etc., so direct instant contact can be established between the RCC and the AMVER vessels in closest proximity to the vessel in distress....AMVER also has a detailed list of these ships' on-board capabilities for rescue and/or ability to provide specialized assistance (such as any medical staff, trained engineers, specialized fire-fighting personnel, etc.)...



Of course, there are some countries that have their own system, for their own flagged vessels and for their own waters....Japan, Australia, New Zealand, India, and Denmark....and we now have more than a few vessel tracking / container tracking companies (Marinetraffic being a popular one for us non-commercial pleasure boat sailors) that can also provide position data...


But, lest we forget that AMVER has pointed search and rescue authorities / RCC's, to the vessels that can assist / complete rescues....which just in the past 20 years has saved the lives of a few thousand mariners!!

Oh, and while it is free to all RCC's and mariners, just an FYI here....AMVER's annual operating budget is just $1.7million USD....now, in my eyes, that's a bargain in our modern world!





As I wrote above, this is not intended to be an off-topic post, nor a long-winded explanation of SAR, AMVER, etc....just wanted to pass on a few things to remember...that while Satellite-AIS is nice....in regards to safety at sea / SAR responses, it's just some additional data that can help, as it's not a replacement for AMVER...

Oh, and I never even got to the NOAA VOS weather / position reports (which are free to send and use, and shared with AMVER) that are so helpful to meteorologists (and computer model technicians) worldwide, in writing forecasts covering our oceans (as well as many great land masses!)....and of course also gives rescuers real-time localized weather info, on-site of any rescue...all for free, worldwide....oh well, maybe in another posting....



Fair winds to all.

John




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


P.S. Here is one minute advert / video from FleetMon, showing just the worldwide ship traffic that are clients of theirs (tracked by both terrestrial AIS and satellite AIS)....there is of course quite a bit more out there, but you get the point that if you're more than a couple hundred miles from the shore of US, UK, France, Aus, New Zealand, Canada, etc., then it's almost certain that it's going to be a merchant vessel along one of these routes/voyages, that will be coming to your assistance / rescue....whether you signal them directly via MF/HF-DSC (or VHF-DSC, if you're close enough to some shipping traffic), or they are directed to you by a RCC (who knew where they were out there, to help you, because of AMVER)...

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Old 09-07-2020, 14:35   #88
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Re: AIS through satellites.

BTW,
If you cannot get that video to play, please just click on the link here, and watch it on Youtube...


Or, look for it here (its the 11th video in this playlist):
HF-DSC Comms
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX


fair winds.

John
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