uAIS and ANT200 Go End of Line

Digital Yacht’s self contained uAIS and ANT200 AIS receivers are now end of line but we’ve replacement solutions that offer improved performance and allow for a more flexible installation.

uAIS was a self contained AIS sensor with a USB wired connection but this was limited to 5m.  In practice this often caused installation issues so we now offer a much neater solution utilising our AIS100USB with the QMax portable antenna (the same type used with our Nomad Class B portable AIS – details HERE).

The AIS100USB is self powered from the PC or MAC USB connection so there’s no need for a separate DC supply.  The QMax antenna features a neat sucker cup type mount allowing easy temporary placement.

ais100 plus qmax

This also has the advantage that the system can be used with other VHF antennas if required allowing for maximum flexibility.  A new part number for the bundle is available ZDIGAIS100QMA and this bundle is available immediately.  The QMax antenna is also available as a stand alone product, part number ZDIGQMA

Potential users of the older ANT200 can now opt for a regular AIS100 (NMEA version) complete with the QMax antenna as a replacement system – order as a ZDIGAIS100 plus ZDIGQMA

AISNet helps improve OnLine AIS coverage of Puget Sound


Arguably the most beautiful sailing location in the USA, it is no surprise that there are always lots of pleasure and commercial vessels in the Puget Sound. This week, we helped one of our customers to upgrade his shore based AIS reception station to one of our latest AISNet units and in so doing helped to improve the AIS coverage, in Puget Sound, of Marine Traffic the world’s largest online AIS network.

Ralph an experienced radio ham, whose home on the Olympic Pennisular is perfect for good AIS reception, contacted us when his initial attempts to send data to Marine Traffic failed. His old setup which required a PC to be permanently on, had been working well for some time but he hoped the new AISNet would free up the PC and reduce power consumption. It quickly became clear that his AISNet was receiving AIS targets and after setting up a test server, in our UK office, we also confirmed that the UDP and TCP data feeds were OK.

AISnet+ Receiver-LR

We have been selling AISNets since 2010, so they are a well proven design, but earlier this summer we released a new version that had a completely new AIS receiver and Network adaptor. Despite the fact that we had done lots of testing in the lab, including sending data to different web servers, there was a nagging doubt that perhaps this new design was not compatible in some way with Marine Traffic. Fortunately the technical support team at Marine Traffic are really fast and efficient and over the course of a couple of nights (due to the time differences), we managed to test and get Ralph’s unit working, by just a simple change to the TCP mode setting.

On  the original AISNet we had always used and recommended “TCP Mixed Mode” for Marine Traffic servers, but with the new AISNet we found that we had to select “TCP Client Mode” or “UDP Mode” to make everything work OK. With the new settings made, Ralph’s data started streaming in and by looking at the statistics found that his new AISNet was giving significantly better reception coverage than his previous setup; 15000km² compared to 3500km².

datauri-file (002)

The improved receiver sensitivity of our AISNet, plus the fact that it was a true dual channel receiver, simultaneously monitoring both AIS channnels and never missing a message, all contributed to the improved coverage. In fact AISNet was on average receiving nearly four times the number of targets per hour compared to Ralph’s old system. As you can imagine, Ralph was very pleased, as were Marine Traffic who now have much better coverage of this area and ultimately everyone sailing in the Puget Sound will benefit from an even better free online AIS service.


VHF Antenna Options for AIS

Splitter v Antennas

One of the most common questions we are asked by our AIS customers, is “what antenna should I use for my AIS ?”, so we thought we would post a short article to provide an answer.

Basically there are two options; fit a second dedicated VHF antenna a suitable distance from the vessels main VHF antenna or use the main antenna for both VHF and AIS by fitting a special device called a “Splitter”.

Generally our recommendation for yacht owners who want to fit an AIS, is to use a “Zero Loss” splitter like our SPL2000. By utilising the main VHF antenna at the top of the mast, you will definitely get maximum transmit range, plus the ease of installation often makes it a cheaper option than paying for a second antenna to be installed.

However, for power boaters who do not benefit from the height advantage of using the main antenna at the top of the mast and for AIS receiver owners where the splitter can often cost more than the AIS receiver itself, it is often desirable to fit a second VHF antenna, particularly if you intend to save money by doing the antenna installation yourself.

We have already covered the issue of AIS antenna separation in another post, so we will not repeat this information again, but we will just touch on the issue of “AIS Tuned” antennas versus normal VHF antennas.

AIS operates on two dedicated channels within the marine VHF frequency range – 156.0 to 162.025 MHz. The two AIS channels are at the top end of this range namely; 161.975 and 162.025 MHz (channels 87B and 88B). Most VHF antennas are designed to give maximum gain across the whole VHF frequency range centred on Channel 16 (156.8 MHz).

Pretty much all of the antenna manufacturers now produce “AIS Tuned” antennas, which have their centre frequency shifted from Channel 16 to 162Mhz (exactly half way between the two AIS frequencies). If you are going to mount your AIS antenna on the stern rail of a yacht or radar arch of a power boat, then using an “AIS tuned” antenna to get an extra bit of gain to compensate for the antenna being effectively at deck level, is a good idea.

AIS Tuned Antenna Graph

The graph above shows how the tuning of the antenna to 162MHz gives it an extra boost in VSWR (gain) across the two AIS frequencies.

Which ever option you choose, having AIS on your boat will without doubt make your sailing experiences safer and less stressful in poor visibility or when crossing busy shipping lanes. Even a simple receiver with a small whip antenna at deck level will keep you informed of what ships are around you and which ones you need to keep an eye on.

Connecting our new AISnode receiver to a Simrad Network

Simrad NSE NMEA2000 + AISnode


Our new AISnode receiver for NMEA2000 networks will work with any AIS compatible chart plotter connected to an NMEA2000 network.

In a previous post we showed how the AISnode could connect to a Raymarine network and in this post we are focusing on Simrad NMEA2000 networks. Simrad adopted their own proprietary connector system for NMEA2000 (SimNet) and so connection of our AISnode will require a SimNet to NMEA2000 adaptor cable (Simrad P/No 24006199).

Once you have the SimNet to NMEA2000 adaptor cable, connect this to the standard NMEA2000 cable that is included with our AISnode and then find a spare SimNet connection on the network to plug the adaptor cable in to. The AISnode will then take its power from the SimNet network and send all received AIS data on to the network.

All of Simrad’s NSS, NSE and NSO chart plotters support AIS and as long as the chart plotter(s) have the latest firmware (free download from the Simrad website) then you will see all of the different types of AIS targets, including the new AIS Man Over Board systems and AIS AtonNs (nav-aids).

It should be noted that all of the latest B&G Zeus Chart Plotters also use SimNet network connectors and so our AISnode will work with these chart plotters in the same way.

For more information on our AISnode, please click here.

Connecting our new AISnode receiver to a Garmin Network

Garmin NMEA2000 + AISNode

Our new AISnode receiver for NMEA2000 networks will work with any AIS compatible chart plotter connected to an NMEA2000 network.

In a previous post we showed how the AISnode could connect to a Raymarine network and in this post we are focusing on Garmin NMEA2000 networks. Garmin adopted the standard NMEA2000 connector system, rather than use their own proprietary connectors and so connection of our AISnode to a Garmin network is even easier, without the need of any special adaptor cables.

Simply find or add a spare “T Piece” connector and the integral NMEA2000 cable of our AISnode will plug straight in, taking its power from the network and sending all received AIS data on to the network.

Garmin’s NMEA2000 AIS implementation is very good and as long as the chart plotter(s) have the latest firmware (free download from the Garmin website) then you will see all of the different types of AIS targets, including the new AIS Man Over Board systems and AIS AtonNs (nav-aids).

For more information on our AISnode, please click here.

New AISnode is the perfect NMEA2000 AIS Receiver

AISNode to Raymarine SeaTalkNG Network

Digital Yacht’s new AISnode is the perfect low cost AIS Receiver for the latest generation of small chart plotters that just have an NMEA2000 interface. The diagram above shows how our AISnode would connect to Raymarine’s popular entry level A65 Multi-Function Display (MFD), the first of this new breed of NMEA2000 only chart plotters.

Raymarine’s version of the industry standard NMEA2000 interface, called SeaTalkNG, is fully compatible with NMEA2000, but features their own connectors and additional proprietary PGN messages. To connect our AISnode unit to the Raymarine Network, it is necessary to purchase a SeaTalkNG to DeviceNet (NMEA2000) cable from Raymarine.

Connecting our AISnode to an NMEA2000 network could not be easier as it takes power from the network and puts data on to the network via its NMEA2000 cable (0.75m) which is terminated in a standard NMEA2000 male connector. To connect AISnode to the Raymarine network you will need to purchase the Female version of the Raymarine adaptor cable which is their Part Number A06045 and costs around £20.

AISnode is being officially launched at the Miami Boat Show next week but for more information click here.

You can also download a Dealer pack from HERE

Getting Maximum VHF/AIS Reception

AIS Antenna on Roof

We are often asked about the best antenna to use with our AISNet Base Station Receiver, which is used by many customers to send AIS data to online AIS websites like Marine Traffic, Pinkfroot, AIS Live, Boat Beacon, Shipfinder, etc. We usually suggest a good quality, AIS tuned antenna, with at least 3dB gain and in most cases this gives a good reception range – up to 20-25miles or more. You can get greater range by going to a more expensive directional Yagi antenna, but these often have a limited beam width and may only receive strong signals from vessels within a 120deg arc of the antenna.

Generally speaking a 1/2 dipole, omni-directional whip antenna is probably the best choice for most installations, as they are generally not too expensive, give a good 3dB of gain and will receive targets through a full 360 degrees. In our opinion, it is better to spend time and money on getting the antenna mounted as high as possible than to spend more money on a higher gain directional antenna.

This week, however, we were contacted by a customer who had bought a well known brand of AIS whip antenna but was only seeing targets out to about 12-15 miles. Looking at the spec of the antenna, everything seemed OK but then we noticed that it came with 20m of RG58 coax cable which, according to the attenuation table below, would lose over -3.6dB negating the benefits of using a 3dB antenna.

Attenuation figures of different types/lengths of Coax Cable
Coax Type 20′ (6m) 40′ (12m) 60′ (18m) 80′ (24m) 100′ (30m)
RG-58 -1.2dB -2.4dB -3.6dB -4.9dB -6.1dB
RG-8X -0.9dB -1.8dB -2.7dB -3.6dB -4.5dB
RG-213 -0.5dB -1.0dB -1.6dB -2.1dB -2.7dB

When selecting antennas, the coax cable is often overlooked and, as we discovered, this can have a significant impact on reception range. We suggested that they looked at an alternative whip antenna that came with no cable but had an N-Type or PL259 type connector on the base of the antenna. This would then allow them to make up their own coax cable, using the minimum possible length of low loss RG-213 coax cable.

Even with RG-213, you can lose approximately 1dB for every 10m of cable that you use and as the AISNet is fairly portable, it is always better to move the AISNet closer to the antenna and reduce the coax cable length. You can always run longer lengths of RJ45 network cable inside the building (which does not suffer the same attenuation as coax cable), or better still use a wireless access point or repeater to wirelessly connect the AISNet to the main router in the building.

For more information on our AISNet Base Station receiver, click here.