Cheap/Easy AIS transponder

[Boatguy30]

With NZ and Fiji currently requiring AIS passage “verification” and I think Thailand already had, need to fit an AIS transponder. Currently have a receiver incorporated into my VHF.

What is the easiest way to go about this? Separate antenna on the stern arc? What AIS are the cheapest and lowest power consumption.

Also does AIS only ping to satellite when you encounter a ship that transmits the data? This is what I’ve been told and considering we saw very few ships between French Polynesia and NZ, it makes this ridiculous “verification” even more annoying!

[CassidyNZ]

I bought one of these 18 months ago, despite all my friends bleating about Chinese junk.

It has functioned perfectly since it was fitted and does a heck of a lot more than “just an AIS”. And as you can see, it is really affordable for a no-nonsense, add-nothing AIS transponder.

The image is an eBay advert.

[Tupaia]

Originally Posted by CassidyNZ

I bought one of these 18 months ago, despite all my friends bleating about Chinese junk.

It has functioned perfectly since it was fitted and does a heck of a lot more than “just an AIS”. And as you can see, it is really affordable for a no-nonsense, add-nothing AIS transponder.

The image is an eBay advert.

The Matsutec 528 is NOT a transponder you need the 528A model or the 33A both transmit and are excellent units.

[clownfishsydney]

I bought a different Matsutec model (no screen, linked to chartplotter) about 5 years ago, still going strong.

[Sos]

I went with an Onwa.
Also a good price but has a plotter so put it down below as redundancy. Put the aerial on the pushpit. Reduced range but enough to avoid targets. Also have receiver on VHF which uses masthead aerial so much more range.

[CassidyNZ]

Originally Posted by Tupaia

The Matsutec 528 is NOT a transponder you need the 528A model or the 33A both transmit and are excellent units.

Mmmmmm . . .

The picture attached is from the same eBay advert and this sticker is exactly the same as the sticker on the back of my unit which I can assure you is a transponder, both receiving and transmitting AIS information.

But believe what you wish, I don’t really care.

[Boatguy30]

Huh, a bit bummed as I recently bought a chart plotter. Didn’t know AIS transmit was an option now.

[kenbo]

It's not a chart plotter even though they are calling it a gps/ais plotter. Pull up a manual for Matsutec hp 528 or hp 33a and see its capabilities.

[Emmalina]

The Matsutec is a great product and it is a plotter but without maps !

[BillKny]

Originally Posted by Boatguy30

Also does AIS only ping to satellite when you encounter a ship that transmits the data? This is what I’ve been told and considering we saw very few ships between French Polynesia and NZ, it makes this ridiculous “verification” even more annoying!

You have "been told" wrong. There is no provision in the AIS protocol for a ship to "transmit" the data you broadcast. As a matter of fact, AIS systems do not "ping" satellites at all. The entire system was designed without any provision for space-based receivers. Clever people managed to figure out ways to collect and deconvolute the data, once they realized it was valuable and could be sold. It is not easy.

As far as I know, satellite reception of and distribution of AIS data is currently limited to Type A transmitters, although the technology is changing quickly, and that limitation is expected to change.

[wingssail]

Originally Posted by Boatguy30

With NZ and Fiji currently requiring AIS passage “verification” and I think Thailand already had, need to fit an AIS transponder. Currently have a receiver incorporated into my VHF.

What is the easiest way to go about this? Separate antenna on the stern arc? What AIS are the cheapest and lowest power consumption.

Also does AIS only ping to satellite when you encounter a ship that transmits the data? This is what I’ve been told and considering we saw very few ships between French Polynesia and NZ, it makes this ridiculous “verification” even more annoying!

The AIS systems required by NZ, Fiji and Thailand (and other countries) transmit via VHF radio, not to satelites. The range is abround 25 miles. They transmit your position continously, not just when you encounter a ship, however if there is nothing within VHF range nobody receives it or tracks it.

If the ship's AIS data is transmitted to a satellite it is on the ship's power and resources, not yours. The ship could transmit it's position and any other signals (such as yours) that it is recieving.

You may connect an AIS transponder to your VHF radio antenna with a splitter or to its own dedicated antenna.

[Tupaia]

Originally Posted by CassidyNZ

Mmmmmm . . .

The picture attached is from the same eBay advert and this sticker is exactly the same as the sticker on the back of my unit which I can assure you is a transponder, both receiving and transmitting AIS information.

But believe what you wish, I don’t really care.

You may well NOT CARE but for the sake of someone buying one of these units I will explain the differences as far as I believe.

They are very poorly described by sellers and often have the wrong pictures.

The 528 accepts and displays AIS data from an external source while the 528A is a TRANSPONDER and can output AIS data.

The 2 units are distinguishable from each other by the number of ports on the rear case the 528 has 3 and the 528A has 4 the 4th port is the VHF antenna connection.






Page 22 of the manual available here http://www.matsutec.cn/Down/HP-528A%...r%20Manual.pdf describes the RS232 / 422 Port connections.


528 - AIS Input / AIS+GPS Input
528A - AIS Output

[IslandHopper]

Originally Posted by CassidyNZ

Mmmmmm . . .

The picture attached is from the same eBay advert and this sticker is exactly the same as the sticker on the back of my unit which I can assure you is a transponder, both receiving and transmitting AIS information.

But believe what you wish, I don’t really care.

Well you should be because if you have the unit in picture you supplied you got stung, the one in the picture is a receive only unit, the dead obvious giveaway is no provision for a VHF Antenna.

Sorry

Edit: Just seen Tupaia's post.

[s/v Jedi]

Contrary to what you guys think, class-A as well as class-B SOTDMA AIS transponders do send messages to satellites. These are the so-called msg27 transmissions, designed for long range AIS and are broadcast every 3 minutes on VHF channels 75 and 76. These two channels have frequencies centered around channel 16, which also means that they need a wideband antenna that is suitable for AIS as well as VHF, like the Vesper antenna.

[IslandHopper]

I thought that was fairly well know these days, a quick look at MarineTraffic will clear that up.

I should add that AIS Transponders have not been designed with the aim of transmitting to Satellites, they are still a terrestrial transponder, satellites have been launched with receivers aimed at picking up the AIS signals.