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Author Topic:   AIS Receive-Only: New Devices
jimh posted 02-12-2011 02:30 PM ET (US)   Profile for jimh   Send Email to jimh  
[I have redacted my own article here because the manufacturer of the device I was discussing has failed to reply to two inquires about it which were made using the manufacturer's own web-based support inquiry system. If the manufacturer is not going to respond to inquiries which are made using his own support system, I do not feel comfortable mentioning their product.--jimh]
jimh posted 02-13-2011 12:44 PM ET (US)     Profile for jimh  Send Email to jimh     
Another new and interesting AIS device to recent be introduced is the COMAR AIS-2-2000 AIS Receiver. This AIS receiver can be very easily integrated into a vessel NMEA-2000 network. You simple connect the device to the network backbone wiring. A drop cable (of unspecified wiring type) is supplied. The device power consumption is so low that it can be powered from the NEMA-2000 network, and thus no separate power source is needed (or can be used). The device requires its own VHF antenna input.

More information is available from the manufacturer, COMAR, who are located in England:

Catalog information:

User manual:

The U.S. retailer of this device appears to be Milltech Marine. Their retail price is $399. See:

The use of an NMEA-2000 network connection to provide the data should make integration of this receiver into an existing NMEA-2000 network very simple.

jimh posted 02-13-2011 12:56 PM ET (US)     Profile for jimh  Send Email to jimh     
A third interesting device is the DIGITAL YACHT ASI100 receiver with NMEA-0183 output. This is another small, low power consumption device for receiving AIS data. The AIS100 does not have the NMEA-0183 multiplexer feature; it has just a single NMEA-0183 output which operates at 38400-bps. The device is noted as being a "true dual channel" receiver, from which one would infer it has parallel receivers.

In the U.S.A. the device is available from CACTUS MARINE for $229: html?cPath=93

Quick-start guide: AIS100%20Quick%20Start%20Guide%20V1_00_Eng.pdf

The device's NMEA-0183 output apparently causes problems when interfacing to some RS-422 inputs. For details for connecting this device to an RS-422 interface as used in the Lowrance HDS-5 and HDS-7 models, see; Tech%2000008-2010%20AIS200%20to%20Lowrance%20HDS5+7.pdf

jimh posted 02-13-2011 01:09 PM ET (US)     Profile for jimh  Send Email to jimh     
All of the above AIS receivers require an antenna input. When installing an AIS receiver on a small boat, there is some concern about the antenna set up to be used with a separate AIS receiver. One must either install a second VHF Marine Band antenna for dedicated use with the AIS receiver, or one must purchase an antenna splitter to share a common VHF Marine Band antenna between the ship's radio and the AIS receiver.

There is some merit to having a separate antenna for the AIS receiver. The second antenna would provide redundancy for the main radio in the event of a failure of its antenna. Also, the cost of installing a second antenna is not particularly high, and may actually cost less than installing an antenna splitter.

Using an antenna splitter avoids installing a second antenna, but the sharing of one antenna between the ship radio and the AIS receiver will cause some problems. There may be a slight loss of transmit power through the splitter. On receive there will be slight loss of signal to each receiver. The AIS receiver will lose its antenna during transmission from the radio. This is not especially worrisome, as the amount of transmit time on a small boat radio is usually limited. Even if using a second and separate antenna for the AIS receiver, there will likely be significant reduction in AIS receiver sensitivity when the radio is transmitting due to high signal levels.

Antenna splitters are rather costly, and may cost more than just installing a second antenna. However, on some small boats, two VHF Marine Band antennas would be difficult to manage, and the antenna splitter approach may be a better option.

jimh posted 02-13-2011 03:51 PM ET (US)     Profile for jimh  Send Email to jimh     
Price flexibility among retailers offering the ICOM MXA5000 AIS receiver has made it more attractive as an AIS receive-only alternative. The MXA5000 incorporates a dual or parallel receiver, RS-422 and RS-232C data outputs, as well as an antenna splitter. The current price among retailers is under $400, with some as low as $325. The initial price for this unit was approximately $600. This unit is significantly larger than the receivers mentioned above, but it does include the antenna coupler or splitter.

Catalog page from ICOM

GOOGLE list of retailers

Jefecinco posted 02-13-2011 07:38 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
The required VHF antenna is, I assume, required to receive only. I also assume most recreational boaters are concerned with AIS targets that are nearby in order to avoid being run over or interfering with commercial traffic. If that is the case a tall antenna is probably not required.

Would a short "rubber ducky" antenna such as those used on hand held VHF transceivers be a good option for an AIS receiver's VHF antenna? If so, a good mounting place on most boats should not be difficult to locate.


jimh posted 02-13-2011 11:50 PM ET (US)     Profile for jimh  Send Email to jimh     
Receivers do not contain transmitters, so the antennas connected to them are used only for receive.
jimh posted 02-14-2011 12:26 AM ET (US)     Profile for jimh  Send Email to jimh     
The AIS transponders on larger vessels are probably transmitting on antennas that are at least 40-feet above the water. This gives those antennas a radio horizon of about 9-miles. This means that even an antenna on your boat mounted at the water level would be able to receive signals from larger boats 9-miles away. Thus a modest mounting height is probably acceptable for an AIS receive-only antenna.

Since the antenna is for receive only we can tolerate a smaller and less efficient antenna, however, I would also consider the AIS antenna as a back-up for the main radio antenna. I'd install at least a full-size quarter wave antenna in lieu of a rubber-duck type loaded short whip.

SJUAE posted 03-07-2011 04:08 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     

I thought you would be going for a SH GX2110 VHF to your HDS-8 and not an independent AIS receiver simply on cost and you can sell or keep your old VHF ?

Is there some technical reason for not going the SH VHF route ?


WT posted 03-07-2011 08:32 PM ET (US)     Profile for WT  Send Email to WT     
It's the GX2150 here in the States. ProdCatID=83&encProdID=A2C2F4EB2A092075389DC4199A79B6C1&DivisionID=3& isArchived=0


jimh posted 03-07-2011 09:01 PM ET (US)     Profile for jimh  Send Email to jimh     
Steve--If I were buying a new radio for my small boat, I certainly would buy a Standard-Horizon radio with built-in AIS receiver.

This article is discussing AIS stand-alone receivers. I have been considering getting one for my house so that I might be able to monitor local commercial boat traffic in the Detroit River area.

WT posted 03-07-2011 09:09 PM ET (US)     Profile for WT  Send Email to WT     
No commercial boats in Detroit River at this moment. But check out California.

And it's free.


jimh posted 03-08-2011 09:43 AM ET (US)     Profile for jimh  Send Email to jimh     
Warren--I am aware of that cooperative network of AIS receivers that show vessel positions on the website you mentioned. I was actually thinking about setting up a receiver to participate in that network. I often see that coverage of our local waterway here, the Detroit River, is spotty. A lot of the AIS data shown on the website Warren linked to probably comes from individual enthusiasts who have set up receivers and joined that network.

Just about all of my boating is done on water which is connected to the oceans, and it is very common to see commercial shipping traffic. I would anticipate that almost all of those commercial vessels will be transmitting AIS signals. If I were a bass fisherman who did most of his boating on inland lakes, an AIS receiver would probably not find many signals to receive.

I very much doubt that anyone, including Homeland Security, could gather information about me or my boat merely by having an AIS receiver in operation on my boat. A receiver is rather well understood to do just that--receive--and not transmit anything. Receivers are not registered, identified, or tracked in any way that I know. You can just buy a receiver and listen to AIS data.

jimh posted 03-08-2011 01:50 PM ET (US)     Profile for jimh  Send Email to jimh     
I think all of towboater's article was a cut-and-paste from something written by someone else and published somewhere else. When quoting someone verbatim you should identify the writer and publisher.

I really don't care to get into the ethics of AIS reception. There are already FCC rules and regulations about intercept of signals and maintaining confidentially which date back to the Communications Act of 1934, but in the case of a signal being broadcast as an aid to navigation, I don't think that doctrine applies, or, at least the FCC appears to not think it does. When an AIS signal is sent from a vessel under mandatory regulations, one could hardly construe it to be private communication since it is a broadcast signal intended for no one in particular.

This is all fodder for an entirely different discussion. This one is just tracking a few new products for the AIS receiver market.

SJUAE posted 03-08-2011 02:29 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     
Warren thanks for the correction "It's the GX2150" :)

Jim I see now why a seperate AIS reciever :) I had also considered joining a programe as a base if I recall correctly Lloyds Shipping were offering a good deal of free equipment providing you met thier location criteria.

You should worry, not in US :) here in UAE I have a compulsory tx/rx system installed so I can be traced. Worse still I had to pay over USD1000 to have it installed.

It's part of the national defence in Abu Dhabi and why UAE is a very safe ME country.


jimh posted 03-08-2011 08:20 PM ET (US)     Profile for jimh  Send Email to jimh     
Steve--You make a good point. If I have to worry about the U.S. Law Enforcement agencies tracking my vessel because I have an AIS receiver in use, that's the day I move to Canada.
jimh posted 03-10-2011 08:38 PM ET (US)     Profile for jimh  Send Email to jimh     
Ship watching has been a long established tradition, and purchase of an AIS receiver is but a manifestation of this centuries-old habit of man.
SJUAE posted 03-10-2011 11:47 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     
I'm with Jim on this

I could probably get by with a compass, piece of string and chart for the sort of boating I do.

The rest is all about enhancing my boating fun whilst the Mrs sits at the bow sun bathing I get to play with my toys and do the nautical version of train spotting :)


jimh posted 03-11-2011 12:32 AM ET (US)     Profile for jimh  Send Email to jimh     
Use of an automated identification system (AIS) receiver provides very valuable information regarding other vessels, which cannot be obtained in any other manner that I know of, and which can be of extreme importance in urgent situations: you can discover the marine mobile service identity (MMSI) of any vessel transmitting an AIS signal. Once you have the MMSI of another vessel, you can make a direct radio call to that vessel using a digital selective calling (DSC) VHF Marine Band radio.

There have been occurrences of "RADAR-assisted" collisions in which a vessel approaching another vessel has tried to initiate radio contact, only to discover--too late--that there was a third vessel to whom they were talking, not to the initial vessel on a collision course. With AIS this sort of ambiguity is eliminated. If I see a commercial vessel approaching on my AIS receiver, I can call him directly using digital selective calling to establish bridge-to-bridge communication so that we can agree on any maneuvering to be done to avoid collision.

jimh posted 03-11-2011 08:32 AM ET (US)     Profile for jimh  Send Email to jimh     
Steve--I like your comparison to train spotting. Here in Detroit it is quite interesting to watch the boats go by, but--unfortunately--the amount of boat traffic has been declining because of the use of much larger vessels. One 1,000-footer has replaced two or three 700-footers, which each replaced two or three 500-footers. When I was young my Dad used to take me to the Detroit River to watch the boats go buy, and there was a constant parade. Now, boat traffic is more spotty and an AIS receiver would be very useful to alert a boat watcher.

I recently used AIS information to time my visit to watch a large freighter come up the Rouge River. This is quite a feat of ship handling, as the width of some bridge openings is just barely sufficient to let the ship pass, and it is quite fun to watch a 700-foot vessel squeeze through some narrow passages while moving ahead at dead slow.

jimh posted 04-26-2011 12:57 PM ET (US)     Profile for jimh  Send Email to jimh     
A new AIS-Receive-Only device has recently been introduced by another UK company. It seems like the AIS receiver and transponder market is dominated by UK companies. Maybe the notion of Great Britain being an island and having a lot of shipping plays into it!

The MarineGadgetRadar AIS Receiver is perhaps the smallest AIS receiver on the market. It is in a form factor equivalent to a USB Dongle. The device is powered from the USB and has a connector for an external antenna. The device has only a single receiver, so it cannot receive two AIS channels simultaneously, but can switch between them. The price is listed in English currency as 99-GBP or 120-EURO. That would be about $175-US. Here is a link for more information.

The manufacturer is RADARGADGETS which is an arm of MIRRORBOW TECHNOLOGIES LTD.

jimh posted 06-19-2011 08:14 AM ET (US)     Profile for jimh  Send Email to jimh     
EM-TRAK is a company new to the AIS equipment market. They have announced the model R100 AIS dual-channel receiver. This device is being sold in the United States by WEST MARINE at $189. See ProductDisplay?productId=795857&catalogId=10001&langId=-1&storeId=11151& storeNum=10103&subdeptNum=10268&classNum=10275

The EM-TRAK R100 appears to be based the new series of OEM products from SRT MARINE TECHNOLOGIES. SRT has been a leading electronics manufacturer in the AIS hardware device market for ten years. Their new AIS products employ software defined radio technology. See: SRT-Marine-Commercial-Press-Release-June-2011.pdf

For more information on software-defined radio technology, see

The EM-RAK R100 AIS receiver has outputs for NMEA-0183 and USB. The R100 should be usable with just about any display device, including laptop computers. When connected via USB, the USB connection also supplies all the power needed to operate the R100. The antenna connection to the receiver is a standard SO-239 UHF series connector. The R100 also includes an NMEA-0183 data multiplexer, and it has an NMEA-0183 input which can be used to connect other devices and multiplex their data onto the single output. This is useful for connection to display devices that do not have multiple inputs.

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