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Search took 0.00 seconds. Search: Posts Made By: Paul Elliott
Forum: Marine Electronics 11-06-2013, 15:08
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Here is a good piece by Ben Ellison on Panbo about the Vesper Watchmate AIS filtering capability: Panbo: The Marine Electronics Hub: Vesper Marine WatchMate, still the leader in AIS collision...
Forum: Marine Electronics 21-05-2013, 08:57
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

For what it's worth, I think the occasional false alarm is a good thing. It tests your equipment and gives you something to practice with. It's when the alarms distract you from something critical...
Forum: Marine Electronics 20-05-2013, 20:52
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Yes, I did mention the static messages in a post several pages back. Both Class-B and Class-A send (or at least try to send) the static ship's data once every six minutes, regardless of speed or...
Forum: Marine Electronics 20-05-2013, 16:26
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

(AIS safety and nav messages)


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...
Forum: Marine Electronics 20-05-2013, 14:55
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

You are probably right, internet AIS sites such as Marinetraffic.com don't pass along navstat. Or they might, I'm not sure.

But I'm not using that. Because I share my raw NMEA AIS data with...
Forum: Marine Electronics 20-05-2013, 13:54
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

From what I heard (and the little I've seen) the Vesper unit is probably the best of the bunch.

On my boat, I have numerous potential AIS displays:

At the helm, a Furuno chartplotter and a...
Forum: Marine Electronics 20-05-2013, 12:56
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Bash, what we are discussing is whether the problem Evans was having was truly related to over-utilization of a scarce resource, or not. I think most of us have implicitly agreed to not argue the...
Forum: Marine Electronics 20-05-2013, 12:31
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Why would you care? Apparently some of us enjoy the topic, and perhaps even the digressions. If it bugs you, see the title "Re: Please turn your AIS off when docked/moored/anchored"? Don't click...
Forum: Marine Electronics 20-05-2013, 12:26
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

As for filtering, if someone wanted to set their alarm filter to exclude Class-B with speed <= 0.1 kts, that wouldn't get me too upset. I would still personally want to see them displayed, just not...
Forum: Marine Electronics 20-05-2013, 12:22
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

How does this possible? Or is it just meant to account for boats that have an incorrect status entered?[/QUOTE]
[/I]

That's my take; in case of incorrect navstat. Or dragging anchor, I suppose.
Forum: Marine Electronics 20-05-2013, 11:43
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

I don't think we're going to arrive at any policy-changing conclusions with the kind of traffic analysis I am doing. We can certainly estimate the slot-utilization by looking at the number of active...
Forum: Marine Electronics 20-05-2013, 11:36
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Here are some NavMonPc screenshots showing Class-A and Class-B target positions in San Francisco bay. I've set the display to show coastline outlines (the screen is centered on Alcatraz Island). To...
Forum: Marine Electronics 20-05-2013, 11:19
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

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...
Forum: Marine Electronics 20-05-2013, 11:03
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Evans, I agree that San Francisco is not a high-traffic area, but we could probably extrapolate using the percentages I recorded.

No promises, but I might turn this into a research project. I...
Forum: Marine Electronics 20-05-2013, 10:44
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

As I mentioned several pages back, the *extremely* slow (3 minute) reporting rate of a stationary Class-B just about removes it from the channel-capacity equation. There is really a very small...
Forum: Marine Electronics 20-05-2013, 10:35
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Hey! That's what I said!
Forum: Marine Electronics 20-05-2013, 09:55
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Here's the data from a quick look at San Francisco area AIS traffic, collected today around 9:00AM PDT:

This data comes from receivers scattered throughout the Bay area. The coverage area picked...
Forum: Marine Electronics 20-05-2013, 09:13
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Good question. I know in Europe the percentage of Class-B is much higher than in the USA, I suppose because it took so long for FCC Class-B approval here. I don't have access to my worldwide AIS...
Forum: Marine Electronics 20-05-2013, 08:21
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

In my neck of the woods they typically sound Asian or perhaps Pakistani (at least to my untrained American ears). But yes, I've heard more than one Russian / Lithuanian / etc, sounding voice, as...
Forum: Marine Electronics 20-05-2013, 01:03
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

The old Iridium satphones only could receive SMS test messages, but the newer ones let you send text messages as well. Not generally useful for communications between vessels though...

AIS/DSC...
Forum: Marine Electronics 20-05-2013, 00:57
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Perhaps that was a pretext? There were U.S. Navy exercises going on in those waters, and as we were leaving there was an announcement of scheduled GPS disruption north of Oahu. I thought is was a...
Forum: Marine Electronics 19-05-2013, 22:26
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

[I realize this is off-topic, but we probably have all the AIS tech-heads following this conversation, so I hope nobody minds.]

About AIS text-messaging:

That' what I was thinking. I've got...
Forum: Marine Electronics 19-05-2013, 20:16
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Class-A systems, yes. I am not aware of a Class-B transponder that will transmit text messages, although some of the display systems can show these messages. If someone knows of a Class-B with this...
Forum: Marine Electronics 19-05-2013, 09:06
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

Here's another AIS position-error story, that I heard from my VTS friend:

One day they were watching their screens, and noticed about a dozen ships drifting away as a fleet, at least as indicated...
Forum: Marine Electronics 19-05-2013, 08:34
Replies: 526
Views: 46,992
Posted By Paul Elliott
Re: Please turn your AIS off when docked/moored/anchored

If you are describing a ship showing up in two places at once, I have no idea, but it almost certainly has to be a display processing bug, not a basic transponder issue. I suppose if the Class-A...
Showing results 1 to 25 of 40
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