ais data feed , ip address?

[flopresti]

Where do I get an internet feed of ais data to feed into opencpn? I see sites that sell a feed? Help, I want to display ais on my opencpn chart. Frank?

[Paul Elliott]

One way is to put up an AIS receiver and send your local data to aishub.net. If you send them your data, they will send you their entire worldwide AIS feed for free (if you ask). But, this will be way too much data for OpenCPN to process without some sort of filtering. I've tried it and it very quickly bogs down and essentially freezes.

Of course if you put up your own AIS receiver then you can send that local data directly to OpenCPN.

If you just want any old AIS data, there are sample files available you can use to feed OpenCPN. There are a couple of them on my NavMonPc website. NavMonPc will send them to OpenCPN via a built-in TCP/IP server or virtual serial port. OpenCPN may be able to play them directly using the Voyage Data Recorder plug-in, but I haven't tried this. My sample files are here: NavMonPc (sample NMEA capture files)

[flopresti]

Thank you Paul for your reply. I'll be playing with your test data and it's good to understand the problems with unfiltered data. So I guess people haven't used this approach, i.e. , not having AIS on my small boat, just using the data over the internet. I've got a first reply from a Bulgarian company which might be able to sell me a feed. (I'll arrange to have internet on my boat as I sail up the coast from NYC to Maine.) I'm a programmer and perhaps I can filter out all data except ships near me. I think I have a good winter project.

Any hints are appreciated. I'm using opencpn... Frank

[conachair]

Originally Posted by flopresti

Thank you Paul for your reply. I'll be playing with your test data and it's good to understand the problems with unfiltered data. So I guess people haven't used this approach, i.e. , not having AIS on my small boat, just using the data over the internet. I've got a first reply from a Bulgarian company which might be able to sell me a feed. (I'll arrange to have internet on my boat as I sail up the coast from NYC to Maine.) I'm a programmer and perhaps I can filter out all data except ships near me. I think I have a good winter project.

Any hints are appreciated. I'm using opencpn... Frank

Bear in mind internet AIS isn't actually much use on a boat sailing in the real world, it's usually too old - I've tried both simultaneously in Opencpn , there can easily be a mile difference between real data received and an internet position. Any kind of collision avoidance from internet data is pretty much useless.
Maybe worth having a look at something like a Daisy AIS or RTL dongle?

[CaptTom]

Originally Posted by conachair

Bear in mind internet AIS isn't actually much use on a boat sailing in the real world...

What he said.

AIS data is a ton of fun to play with. But as for actually using it in real-life situations, I'd want a local AIS receiver, at a minimum. Personally, I'd go with the transceiver.

Do you need it everywhere and in all conditions? No. But those few times you're in congested waters in poor visibility, you'll understand the value pretty quickly. It puts you almost on an equal footing with the commercial vessels. You still have yahoos in recreational boats to deal with, but the big boys have you covered.

[flopresti]

In summary. So a few of you have experimented with using an internet feed for AIS data. and find it too slow, too old data. I should use Daisy AIS or RTL dongle and have my boat AIS compliant.... If this weren't the case, I guess many small boats wouldn't bother with sending out AIS data but would just get ais data and overlay it onto their opencpn nav window.

Perhaps since only a few have tried, there is a better small area feed for local AIS data?? Thank you for sharing your experience... Frank

[rgleason]

Re: small area feed. As others have stated, use rtldsr or dAISy ais reciever. Best inexpensive approach. I much prefer the daisy. DAISy HAT for RPI is available too.

[Paul Elliott]

Frank, it sounds like you may be thinking that you need to transmit AIS on your boat in order to receive it. Actually, you can install a fairly inexpensive receive-only unit that will easily feed OpenCPN. The RTL Dongle is probably the cheapest approach, but there are plenty of options. However, many boaters have decided that installing a full AIS transponder is worth the extra money.

[rgleason]

Thank you Paul. Here is the Link to dAISy AIS Receivers

https://opencpn.org/wiki/dokuwiki/do...is_-_receivers

[skipperearly]

As mentioned above SDR-RTL receivers are a very lowcost solution - available e.g. from openplotter - Sailoog Shop

openplotter may be an interesting option for you out of the box. And soon they will also offer dedicated mariners hats for raspi users.

[ranger58sb]

Originally Posted by conachair

Bear in mind internet AIS isn't actually much use on a boat sailing in the real world, it's usually too old - I've tried both simultaneously in Opencpn , there can easily be a mile difference between real data received and an internet position. Any kind of collision avoidance from internet data is pretty much useless.

Even real AIS can have some time-lag issues. I watched a small powerboat cross our path quickly once with the good ol' Mark I*** eyeballs... and his AIS track didn't cross our path until about 2 minutes later.

Another issue is that you having (sending) "Internet AIS" (?) doesn't do much to help other nearby traffic. If it's not a real AIS signal, I wouldn't "see" you on our AIS display system, since our main instruments aren't tied in the Internet while underway.

-Chris

[flopresti]

Thank you all for your ideas. I will have the winter to try to get some ais input for opencpn working on my laptop. I hope to be able to do this with a simple hookup to the boat's vhf. Any additional links to tech info are appreciated. Thank's Frank.lopresti@nyu.edu

[Paul Elliott]

Originally Posted by flopresti

Thank you all for your ideas. I will have the winter to try to get some ais input for opencpn working on my laptop. I hope to be able to do this with a simple hookup to the boat's vhf. Any additional links to tech info are appreciated. Thank's Frank.lopresti@nyu.edu

Hooking up to a marine VHF transceiver will be problematic. I believe you will have to open up the radio and solder a to an internal connection, then use a program such as "AISMon" to decode the signals. You will not be able to use your VHF for regular communications (Chan 16, etc) while it is being used for AIS. Here's a link that discusses this: https://help.marinetraffic.com/hc/en...-AIS-Receiver-

On the other hand, there are marine VHF radios that have built-in AIS receivers, and a NMEA0183 output that you can connect to OCPN through a serial port. Standard Horizon and I believe Icom make this type of radio.

You might check out Milltech Marine (https://www.milltechmarine.com/). They are a good source for AIS gear and info. It's not that hard.

[flopresti]

I hope to get ais (just receiving) up and running using opencpn.(without my small boat being registered).. I'll report on my progress over the winter...

I purchased a dAISy 2+ dual-channel AIS Receiver with NMEA 0183 for about $89 .... and will play with this when it arrives. I will probably need a vhf/ais antenna splitter but I'll see if it's necessary when I have the DAISY. I also saw
AMEC CYPHO-150S AIS Receiver with Antenna Splitter for around $200... both receiver and splitter... perhaps others have experience with the AMEC .... I'll report on my progress

[Paul Elliott]

For those who are interested, I've been analyzing the data I get from AisHub.net. This is the worldwide AIS data sharing system, where anyone who sends then their received data gets to use the combined worldwide feed for any purpose whatsoever.

So I was wondering about the update rate. I was tracking a Class-A target that should have been reporting every ten seconds. The AisHub data for that ship was coming in roughly once per minute. I checked several Class-A and Class-B targets, and they all had a once-per-minute update rate, +/- fifteen seconds or so. Occasionally several minutes would go by without an update.

This is not good enough for close-quarters action. It's useful for other purposes, or I suppose targets that are a long ways off, but not for any time-critical maneuvering. And this shouldn't be a surprise. Don't most internet AIS monitoring sites have a "not to be used for navigation" disclaimer, citing just this issue?