Not all AIS receivers are the same….

BoatBeacon (a company with some brilliant marine telematics capabilities) are rapidly expanding their AIS base station coverage and utilising Digital Yacht AIS products for exceptional performance.  A recent installation in Benidorm shows that not all AIS receivers perform the same.  The picture below shows previous coverage using a 3rd party AIS.

AIS BENIDORM BEFORE

They then upgraded to a Digital Yacht AIS receiver and the performance improvements are dramatic – an 8 fold increase in data received and over 4 times as many ships all from the same location and antenna.  You’ll notice too how ATONs and AIS base stations are correctly decoded by all Digital Yacht receivers

AIS BENIDORM AFTER

You can also see the dramatic increase in data traffic in the graph below when the new receiver was turned on at 2:10pm.  Digital Yacht – better AIS solutions.

AIS TARGET GRAPH

AISNet helps improve OnLine AIS coverage of Puget Sound

Puget

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.

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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.

datauri-file

National Coast Watch Doing a Great Job

NCI Mablethorpe Station

Since their formation in 1994, the UK’s National Coast Watch Institution (NCI) have been doing invaluable work around the UK coastline. With 50 stations, manned by over 2000 volunteers, the NCI are the marine watch keepers, alerting and coordinate MCA and RNLI rescue operations whilst also monitoring the general coastal environment and weather conditions.

A number of the NCI stations have Digital Yacht AIS units installed, including Mablethorpe (shown above) and the most recent installation was recently completed at Barry Island in South Wales (image below). Using one of our latest AISNet units, they were able to receive AIS targets all the way across the Bristol Channel and up the Avon.

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It is not always possible to get an internet connection in some of these very remote NCI stations, but in the Barry station, AISNet was able to send live reception data to an AIS webserver hosted by PocketMariner where it could be viewed online or on a mobile device using their Boat Beacon or our NavLink apps. The image below shows the typical reception the NCI station would see and you can click here to see a live view of the Barry Island station.

Boat Watch Live View

The NCI is entirely staffed by volunteers, with funding managed by a Board of Trustees based on a constitution agreed by the Charity Commission. It may not be as dramatic and high profile as the RNLI, but the work they do is of equal importance and relies heavily on local support and donations. If you ever chance upon an NCI station, just knock on the door and the officers on watch will give you a warm welcome and be delighted to show you what they do.

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AISNET Plus – A powerful new AIS Base Station Receiver

AISnet+ is a new enhanced version of our popular AISnet AIS base station receiver.  Both models will continue to be available but AISnet+ features some new, unique interfacing capabilities.

Both devices are fitted with a network/RJ45 interface.  They are designed for installation on shore side facilities such as ports, marinas or platforms for connection to the internet via a suitable router.  Local AIS traffic decoded by the AISnet receiver can then be sent to AIS internet providers such as Marine Traffic and AISLive.

aisnet plus The new AISnet+ device brings new connectivity options with a sophisticated internal router allowing for Open VPN connections and wireless connectivity as well as via a LAN cable.  Like the AISnet receiver, it has also has a USB interface for a local PC or MAC.  Open VPN allows for secure AISnet to server communications for high reliability and security – its ideal for military applications.

AISnet+uses the very latest generation, high sensitivity dual channel AIS receiver for the best possible receiver performance.  Both Class A and Class B transmissions are fully decoded including ATONs, SARTs and other specialist AIS signals.  Indicator lights are now built in showing receiver and network status.

aisnet base station-01

AISnet+ ships with a 110/220V AC adaptor (with universal plug adaptors for global markets) and a simple to use configuration application/CD for both PC and MAC.  It can also be powered from 12V DC.  It is available now priced at £1000 plus VAT where applicable ($1600/EUR1400)

Superyacht Applications from Digital Yacht – A Guide For Installers

Digital Yacht products integrate easily into superyacht systems.  This new guide for installers and dealers shows some typical systems ranging from AIS tender tracking thorough to iPad navigation, marine PCs and on board NMEA networking – all great, value adding solutions.  Come and see these latest systems at the Miami Boat Show Digital Yacht Booth 2509 12-16 Feb 2015

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You can download a copy of the presentation from HERE

You can download our latest product guide in US$ from HERE

AISNET – A great solution for vessel tracking

AISNET is Digital yacht’s low cost AIS base station receiver.  It’s designed to be mounted ashore and connected to the internet via its RJ45 network interface.  Local AIS data can then be uploaded to websites such as Marine Traffic to allow easy web viewing of AIS traffic in your region.  It’s also fitted with a USB connection for a local PC.  Here’s Paul Sumpner, Digital Yacht’s CTO at METS 2014 telling us a bit more about this niche product.

 

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.