Why is an AIS transmitter so much more expensive than a receiver?

[David Dennis]

VHF transmitters are dirt cheap, and AIS transmission is just low-power VHF + electronics, right?

As far as I can tell, the minimum cost of an AIS transmitter is around $600, and receivers are around $300. I would actually think most of the complexity is in the receiver, at least for the devices with displays.

Why so much for an AIS transmitter?

David

[donradcliffe]

AIS transponders need a built-in GPS as well as a VHF receiver and transmiter, and there are far fewer of them than VHF radios, so $500 isn't a bad price to start with. The price should come down with time.

[roverhi]

Bought an AIS transceiver from West Marine 4 years ago for less than $500. Hard to believe that you can't find one cheaper today. Transceivers are more expensive because they, drum roll, transmit as well as receive. You've got the added electronics of the transmitter as well as a GPS and antenna to be able to transmit location along with all the other data from the AIS.

[colemj]

Receivers are below $200. $300 will buy you a DSC VHF radio with AIS receive and GPS built in.

AIS transceivers are dropping in price constantly, but they have both more complexity (another radio stage), more certification costs, and contain more interface stuff like wifi, N2K, etc (this is added in because of the market desires).

Mark

[continuouswave]

Originally Posted by David Dennis

...I would actually think most of the complexity is in the receiver, at least for the devices with displays.

The AIS transceiver contains actually four receivers and a transmitter. The tranceiver is more complex than any receiver. It has to first listen to the AIS channels to establish what slots are already reserved for use. Then it has to pick a slot for itself to transmit in. Then (if Class-B) it has to listen for a few milliseconds in that slot to make sure it is not in use. Then it transmits. And it has to listen to the DSC channel in case some commands are sent there. And it has a GPS receiver.

When it transmits, it has to encode the same or more data that the receiver has to decode.

And the transmitter has to be frequency agile, in case it is commanded to a new channel in some region.

AIS receivers sometimes have simple chart plotters built onto them. The complexity of a chart plotter is not part of the AIS receiver. All the AIS receiver needs to do is put out !AIVDM sentences. It can let some other device plot the positions, calculate the CPA and TCPA, and log all the data.

[OceanSeaSpray]

There isn't really any more hardware in a simple class-B AIS transponder than what is found in a VHF indeed - other than a cheap GPS module, because the rest is software and VHF radios are also microprocessor-controlled these days.

AIS receivers weren't cheap either until people started ditching them out to ask for transmitters instead. I think they just attract a premium, because they are the little "must have" of the moment.

I bought one of those disregarded small AIS receivers and built a simple alarm module I connected to the serial data port. I don't give a damn about the AIS message and I have eyes to work out collision vectors, but if there is anything sending an AIS message in range while I am offshore, this I want to know!

Broadcasting my position all around is something I don't particularly care for on the other hand.

Regards

[Canibul]

Originally Posted by OceanSeaSpray

Broadcasting my position all around is something I don't particularly care for on the other hand.

hear hear. I was beginning to think that I was the last one alive who feels this way. Notice the government mandates that THEY have the ability to track us, for OUR protection and safety. And if you want to say no, these days your fellow sailors look at you aghast like you dissed Facebook or something. You don't want to be tracked? What's WRONG with YOU???

[mrm]

Originally Posted by donradcliffe

AIS transponders need a built-in GPS as well as a VHF receiver and transmiter, and there are far fewer of them than VHF radios, so $500 isn't a bad price to start with. The price should come down with time.

A complete, surface mounted GPS module with an integrated antenna, costs approximately US$17, in single unit quantities. GPS/GLONASS capability does not influence price either. Just for some solid data context to the components price argument.

[denverd0n]

A transmitter is sending a signal out. As such, it can interfere with other transmissions, it can interfere with electrical and electronic devices nearby, it can create all kinds of havoc. That's why we have type certifications for transmitters. We want to be sure that they transmit a clean signal within the bandwidth that they are supposed to be using. We want to be sure that they don't create all of the havoc that they COULD create if they were not designed and built properly.

Receivers have none of these issues. They don't send anything out. Hence, receivers are always less expensive than transmitters.

[IdoraKeeper]

Originally Posted by Canibul

hear hear. I was beginning to think that I was the last one alive who feels this way. Notice the government mandates that THEY have the ability to track us, for OUR protection and safety. And if you want to say no, these days your fellow sailors look at you aghast like you dissed Facebook or something. You don't want to be tracked? What's WRONG with YOU???

Fourty seven pictures with circles and arrows and paragraph on the back of each one explaining how it is evidence to be used against you.

[goboatingnow]

Originally Posted by Canibul

hear hear. I was beginning to think that I was the last one alive who feels this way. Notice the government mandates that THEY have the ability to track us, for OUR protection and safety. And if you want to say no, these days your fellow sailors look at you aghast like you dissed Facebook or something. You don't want to be tracked? What's WRONG with YOU???

I see the tin foil hat brigade is alive and well. If the US ( and it's really only the US ) that's wants to track you I suspect whether you transmit AIS or not is irrelevant.

Of course letting ships and other users know you are there and that they should avoid you on the other hand might actually contribute to yours and their safety. Darwin of course will intervene here ultimately !!!

Dave

[darylat8750]

What the market will bear.

[colemj]

Originally Posted by Canibul

hear hear. I was beginning to think that I was the last one alive who feels this way. Notice the government mandates that THEY have the ability to track us, for OUR protection and safety. And if you want to say no, these days your fellow sailors look at you aghast like you dissed Facebook or something. You don't want to be tracked? What's WRONG with YOU???

Do you have a cell phone or connected device? Use the internet with a common web browser through a standard connection? Have a boat with a radar cross-section? If so, your ship has sailed, so to speak.

Mark

[skipmac]

Originally Posted by IdoraKeeper

Fourty seven pictures with circles and arrows and paragraph on the back of each one explaining how it is evidence to be used against you.

Would you believe 27, 8X10 color, glossy photographs (with circles and arrows etc)?

[Capt.Don]

Originally Posted by mrm

A complete, surface mounted GPS module with an integrated antenna, costs approximately US$17, in single unit quantities. GPS/GLONASS capability does not influence price either. Just for some solid data context to the components price argument.

More info on this AIS receiver, please!