AIS will get you out of a tight spot before it is too late.

Q. What is AIS, Automatic Identification System?

AIS is the digital transmission of data derived from GPS and shipboard sensors, via VHF radio. Operating according to digital communication protocols that give a voiceless exchange of navigation information between vessels and shore-side receivers. This information is continually transmitted in real-time and received by all AIS-equipped ships and shore stations within VHF radio range.

Q. Why is AIS data only transmitted on Ch 87 and 88 ?

Because these channels prior to the 2000 BASEL AGREEMENT
were not designated for any specific purpose apart from public access.
The AIS receive frequencies have been omitted from virtually all modern VHf radios.
So that the average person now will need to purchase an dedicated overpriced expensive AIS receiver, costing many hundreds of Dollars.
For the AIS frequency information Please see the next question

Q.On whch frequencies is AIS data transitted?

CH 87 -- 161.975 MHz and
CH 88 -- 162.025 MHz

Q. When did AIS regulations become effective?

AIS Regulations became effective November 21, 2003. All vessels required to have an AIS as denoted in 33 CFR ? 164.46(a), must have a USCG 'type-approved' and 'properly nstalled' AIS transponder on the vessel no later than December 31, 2004.

Q. Should the aisdigital AIS receiver have its own antenna?

Yes, the antenna can just be a piece of 50 Ohm coax: No need for a expensive aerial.
Mounted 2 to 3 meters above sea level is fine.
DIY details for such an antenna are on the DVD.

Q. Can AIS data used as overlay in my navigation program?

Yes, If your nav program supports layers. For example: "MaxSea v12", "OpenCPN" and more.

Q. Does aisdigital supply electronic charts also?

Yes, we can supply recent worldwide vector charts on DVD.
They range from detailed harbor to Ocean charts.
They are compatible with most navigation software, including the free version of OpenCpn.

Q. What are Vector charts?

In short, the further you zoom in, the more detail appears on screen.

Q. Is my laptop suitable?

99.9% of modern laptops are quite suitable for the display of AIS data, however some sound cards can not handle the flow of incoming information or have internal blocks set in the registry to prevent pirating.

Q. Is my tablet ot phone suitable?

Your Tablet ot phone must support OTG (on the go). The majority devices of Samsung are.
You can download free OTG apps from Google Play store, if needed.

Q. Do I have a guarantee that AIS targets will display on my laptop?

NOT 100%". It is up to the client to follow the comprehensive instructions provided and have sufficient knowledge for the installation. As this is out of our hands, no refunds are given. All the hardware is checked before dispatch and the software provided is suitable for the purpose.

Q. Can I receive AIS data even though I don't have a boat?

Yes, everybody can receive AIS data, as long as your VHF antenna is located near the coast or harbour. The higher you are above sea level, the bigger your reception range is.

Q. Do all ships transmit AIS data?

For vessels on international voyages AIS is mandatory from vessels over 300GT . For vessels on national voyages it is mandatory from 500GT. and mandatory for all passenger ships.

Q. What kind of information is transmitted over AIS?

Vessels name, call sign, MMSI number, IMO number, GPS-position, course over ground, speed over ground, true heading, rate of turn, length, beam, draught, type of vessel, navigational status, destination and estimated time of arrival.

Q. How will the Automatic Identification System help to increase safety?

The AIS corroborates and provides identification and position of vessels not always possible through voice radio communication or radar alone and creates an awareness of vessels in the maritime domain. The full benefits of AIS are only achieved when it is fully integrated and displayed on other shipboard navigation systems (e.g. Electronic charts Data and Information System (ECDIS), ECS, Radar, Automatic Radar Plotting Aide (ARPA), Tracking Devices etc. Most commercial vessels comply with this.

Q. How much do Automatic Identification System transponders cost?

An approved AIS transponder can range in price between $2500 and $5000, not including installation cost which will vary considerably depending on the level of integration of the AIS with other shipboard systems; e.g. radar, speed log, rate of turn indicator, navigation positioning system, ECDIS, etc.

Q. Can the system receive the AIS information further than 10 nautical miles?

When your VHF antenna is set at 3 meters above the sea level, the farthest receivable distance is around 25 nautical miles, as ships antennas are higher than 35m above sea level

Q. Can I use my old GPS?

The GPS connected to the AIS or laptop must fulfill the IMO performance standard. It means that the output from the GPS must be in WGS 84 and that there is no dead reckoning of the position.

Q. Under what circumstances are commercial vessels allowed to switch off their AIS?

Where the master believes it is necessary for the safety of the crew and/or the vessel and/or the cargo. Eg Repairs, suspected pirate areas etc

Q. What are the differences between AIS Class A transponders and AIS Class B transponders?

Class B is intended to be a simpler, less expensive version for the use on non-SOLAS vessels. Class B is intended primarily for recreational crafts.

Q. When do the new VHF channels become operational?

The New VHF Channels
go into operation on 1 Jan. 2018 around the world except in the Americas.

Q. How is GPS and chart datum collected?

AIS co-ordinates are in WGS-84, the co-ordinate system used by GPS.

Q. How is the AIS data limited to safety information?

ITU-R recommendation M.1371-1 limits AIS transmission on AIS designated channels (87and 88) to maritime safety related messages.


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