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Old 20-05-2013, 16:40   #466
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by s/v Jedi View Post
That's the point, only class-A units get those...
Negative, I can and do get safety and nav messages on the vesper. It sounds like the difference to class A is that I cannot send any text messages.
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Old 20-05-2013, 16:44   #467
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Originally Posted by s/v Jedi View Post

That's the point, only class-A units get those...
No class B can receive safety text messages if the unit says it can display them

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Old 20-05-2013, 16:44   #468
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by estarzinger View Post
Negative, I can get safety and nav messages on the vesper.
You can?! that is good news. But you can't send messages? I think there are more differences among the offered units than are apparent to us or at least to me. We should compare the popular ones. I would also like to know which CPU is used as I have sen units that just got overloaded on their CPU for plotting many targets; they slowed down until stand still.
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Old 20-05-2013, 16:45   #469
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by estarzinger View Post
One would suppose wrongly

I have a wireless remote for the autopilot. I can change course, or even 'directly hand steer' from anywhere.

I would most often be near the front end of the cockpit where the mainsail sheet is, and I do have a remote vhf mic plugged in there also. But I could really be anywhere - from the helm to the bow (say freeing the anchor).
Ah, that sounds nice, but Michele and I would have steering wars if we both had control of the boat...

Is the front of the cockpit near a dodger? The iPad should do good in shade.

Uhhh, freeing the anchor shouldn't be an AIS situation...

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Old 20-05-2013, 16:50   #470
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Navstat is used a little bit. The reporting intervals are mostly determined by speed, and rate of turn.

Class-B:
SOG > 2kts -- 30 seconds
SOG <= 2 kts -- 3 minutes

Class-A:
Navstat anchored or moored, SOG <= 3 kts -- 3 minutes
Navstat anchored or moored, SOG > 3 kts -- 10 seconds
SOG 0-14 kts -- 10 seconds
SOG 0-14 kts and changing course -- 3.333 seconds
SOG 14-23 kts -- 6 seconds
SOG 14-23 kts and changing course -- 6 seconds
SOG > 23 kts -- 6 seconds
SOG > 23 kts and changing course -- 6 seconds
Also need to add the ship data feilds every 6 mins. They take an additional 2 slots. All class b even stationary ones still try to transmit these as. I understand it. So a moving class b uses 14 slots every 6 mins and a stationary uses 4 every 6 mins.
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Old 20-05-2013, 16:52   #471
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Class B can receive text messages but cannot send then


Equally class b can respond to interrogations not not generate then , so I wonder Nick how your system is doing that. ( or is it a local thing )

The tech specs addendum on class B CSTDMA gives a useful comparison between A and b functionality by message type.

I should add that while TDMA telecommands are built into class B, DSC telecommands are optional.

As I said B must process message 22 and 23 which allows the rate reporting interval to be changed


Rate intervals can be changed between 5s to 10 mins and quiet times intervals upto 15 minutes can be sent.

Note that message 22 gets the geographic boundary areas , which class B has to handle. Interesting cause I thought that was only a class B feature. , this means Evans system could have been automatically controlled on entering a geographic area.

Does the vesper indicate any of this stuff ?



It would be really nice to get someone like vesper on the thread

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Old 20-05-2013, 17:04   #472
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by goboatingnow View Post
Equally class b can respond to interrogations not not generate then , so I wonder Nick how your system is doing that. ( or is it a local thing )
I have class-A. Actually, I have a development unit and can load either class-A, class-B or class-A+class-B software. I helped during development and this is a left-over (SmartRadio, which produces the internals for many brands AIS gear)
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Old 20-05-2013, 17:09   #473
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Originally Posted by s/v Jedi View Post

I have class-A. Actually, I have a development unit and can load either class-A, class-B or class-A+class-B software. I helped during development and this is a left-over (SmartRadio, which produces the internals for many brands AIS gear)
Ah hah

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Old 20-05-2013, 17:16   #474
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Originally Posted by s/v Jedi View Post

I have class-A. Actually, I have a development unit and can load either class-A, class-B or class-A+class-B software. I helped during development and this is a left-over (SmartRadio, which produces the internals for many brands AIS gear)
That wouldn't be the SR 261 would it , ahem certification ahem

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Old 20-05-2013, 17:23   #475
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Re: Please turn your AIS off when docked/moored/anchored

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ahem certification ahem
Run Nick, Run!

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Old 20-05-2013, 17:26   #476
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Re: Please turn your AIS off when docked/moored/anchored

(AIS safety and nav messages)
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Originally Posted by s/v Jedi View Post
That's the point, only class-A units get those...
Well, anyone can receive them, and the receiver in a Class-B transponder does that just fine. The trick is that whatever you're using to display your AIS data, be it a chartplotter, computer, stand-alone unit, etc, has to decode and display the messages. I don't know many / any that do...

But some might, and they all could.
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Old 20-05-2013, 17:26   #477
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by goboatingnow View Post
Rate intervals can be changed between 5s to 10 mins and quiet times intervals upto 15 minutes can be sent.
Ah, this might answer the question I have been waiting to see answered. Evans asked about the situation when his unit is externally shut down and he had no control over it. Seemed quite alarming (no pun intended) to me if one then sailed out of that area without it coming back on, or the controller simply forgets.

But if I understand this correctly, "quiet" can only last 15min without further action by someone for another 15min?

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Old 20-05-2013, 17:46   #478
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Ah, this might answer the question I have been waiting to see answered. Evans asked about the situation when his unit is externally shut down and he had no control over it. Seemed quite alarming (no pun intended) to me if one then sailed out of that area without it coming back on, or the controller simply forgets.

But if I understand this correctly, "quiet" can only last 15min without further action by someone for another 15min?

Mark
Yes a further message type 23 has to be sent. To continue the quiet period.

Note also that all AIS devices when they start operating in autonomous mode , ie with no other Tx in range either reset to default or actually start reporting faster.

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Old 20-05-2013, 17:52   #479
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Re: Please turn your AIS off when docked/moored/anchored

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That wouldn't be the SR 261 would it , ahem certification ahem

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Old 20-05-2013, 18:00   #480
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Re: Please turn your AIS off when docked/moored/anchored

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That wouldn't be the SR 261 would it , ahem certification ahem

Dave
Kidding aside, mine is a development (pre) version of the SR261. With programmer to change software etc. I spent 4 months with these guys to get all the bugs out and test it in real conditions, until it worked. There were some AIS anomalies around the ABC's during those months

Also, right after that, I worked with Y-tronics to support the SmartRadio transponders in their Yacht-AIS software. This is why it can program all the static data incl. class-A for SmartRadio, send/receive messages etc. It's a shame he discontinued selling the software.
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