Nomad 2 – Portable AIS Transponder

If the AIS transponder doesn’t have a built-in VHF splitter (i.e. AIT5000), there are 2 options: either install a dedicated VHF antenna for AIS or install an antenna splitter so that the main VHF antenna is used for both VHF radio and AIS.

For those who want to use their existing VHF antenna, then we recommend the use of a certified zero loss VHF antenna splitter such as our SPL1500 and SPL2000. Please do not use a non-zero loss certified VHF antenna splitter. They are inexpensive, but they can destroy your AIS transponder.

For those who want to install a VHF antenna dedicated to AIS, then we recommend a VHF antenna tuned to AIS frequencies. The AIS transmission and reception works on 2 dedicated channels which use the frequencies 161.975 and 162.025 MHz (channel 87B and 88B). VHF frequencies in the maritime environment use frequencies from 156.0 to 162.025 MHz and most VHF antennas are designed to provide maximum gain on channel 16 (156.8 MHz). You can now find antennas on the market dedicated to AIS frequencies such as the HA156 antenna.

These antennas, dedicated to AIS frequencies, offer maximum gain at 162 MHz (which is the centre between the 2 AIS frequencies 161.975 and 162.025 MHz). So if you install a VHF antenna instead of a VHF antenna splitter for your AIS receiver or transponder, then choose an AIS frequency VHF antenna to compensate for the loss due to the installation of the antenna lower down than the main VHF antenna at the top of the mast. The graph below shows how a dedicated AIS frequency antenna (162 MHz) provides a better VSWR and therefore a better transmission and reception.

This is a very valid question. Especially if you have spent a few hours installing the transponder then knowing that it is working OK is very important. Using the proAIS2 configuration software allows you to see if the GPS position is OK. You can monitor the AIS reception of other vessels. As well as ensure that there are no errors or alarms. However, if you are new to AIS, there is always that nagging doubt as to whether other vessels are seeing you.

The best test of a Class B transponder is to ask someone else in your marina, who has AIS, to check that they are receiving you on their system. If your vessel is stationary, then a transponder will only transmit every 3 minutes. This increases to every 30 seconds when your speed over the ground (SOG) is greater than 2 knots. Therefore, do allow some time for them to detect you. Also when they first receive your transmission, the only data they will see is your position, speed, course and MMSI number. It can take up to 6 minutes to receive your “Static Data” (boat name, call sign, vessel type, dimensions, etc.). This is normal and is the way the AIS system regulates the amount of data being transmitted.

The other increasingly common method of testing an AIS transponder is to look on one of the online “live” AIS websites and the most popular of the free services is MarineTraffic.com

However, it is important for you to be aware of the limitations of these online sites. As a result, do not assume that you will always be picked up by them. Each of the different online services are only as good as their network of AIS receiving stations. In many cases enthusiasts/volunteers operate these. In some areas the coverage is great but there are definitely “holes” in coverage.

AIS uses VHF transmissions so range is limited to line of sight.  With the compact antenna you should be able to transmit up to 5NM and receive data from other vessels at 10-12NM.  Shore stations would typically pick you up at 25NM.

Connected to a mast top antenna will give standard Class B ranges of up to 20NM as the power output (2W) is the same as all other Class B AIS.

If the unit is unprogrammed, it will hence act as a receiver only outputting GPS and AIS data via WiFi and USB

USB battery packs have different capacities, typically quoted in mA/Hours.  The table below, shows the continuous use time for the most common types.

Most users will use a 3rd party mount like a mobile phone holder, RokLok, RailBlaza or RAM mount.  The fixing holes also allow for a cable tie to be utilised and Nomad ships with two strips of high strength adhesive Velcro for a temporary solution.

Nomad can also be permanently mounted using the screw holes provided onto a vertical bulkhead.  It is important to mount Nomad vertically so that the internal GPS antenna is facing the sky

Up to 7 devices can connect wirelessly to Nomad at any time, which supports TCP (single device) and UDP (multiple devices) protocols.

The Wi-Fi will typically footprint a boat up to 25m LOA.

Contact us if you need a bigger footprint or have a steel or carbon vessel.

No internet connection is required for AIS apps to run and so non GPS/WiFi only tablets can be utilised with an appropriate app for navigation as Nomad provides a GPS feed.

Yes

Nomad 2 has a USB interface (for power and data) that can connect to a PC or MAC.  Any AIS compatible navigation software can be used and the PC will create a virtual com port.  Digital Yacht offer free SmarterTrack Lite viewing software as well as premium SmarterTrack software for use with Navionics charts for detailed charting and navigation.  It’s also compatible with popular programs like TimeZero, Nobeltec, Expedition, SeaPro and Open CPN.  Most modern programs also accept a TCP/IP or UDP feed via the wireless link, but do double check before purchasing.

Apps on iPads, tablets and smartphones will use the wireless link to connect to Nomad.  Check www.digitalyacht.net for iOS and Android apps as there are a huge number of popular charting and navigation programs.

The GV30 antenna can be used as an emergency VHF antenna.  Remember it has a BNC connector so a BNC to PL259 adaptor may be required for a regular VHF.

Nomad 2 has a built in interface for programming – simply connect your mobile device to its wifi and login to its functionality.  No apps are required.  proAIS 2 programming software can also be used on a PC or MAC via the USB interface.