howard mcsweeney1 wrote:thanks for info Jacqui, just looked in at the marine traffic one, very addictive like our channel traffic one on a massive scale.
"Channel Traffic" and MarineTraffic are one and the same. If you look at the blue bar at the bottom of the Channel Traffic screen you can see that it is a link to the local area from the MarineTraffic site .
MarineTraffic is global and seems to be the most popular of the numerous websites which have sprung up since the introduction of AIS on shipping in recent years.
These involve a host of dedicated amateurs who obtain their own AIS receiver and feed the output to the websites concerned.
Coverage is limited to those coastal areas where the amateurs are situated and the VHF range from their location, typically a minimum of 20 nautical miles, much further if they have a aerial which is high up and unobstructed.
The AIS system works via transponders on each vessel which communicate with each other and maritime shore stations on dedicated VHF channels via time division multiplex with each transponder transmitting in its own time slot.
It is very useful to us at sea as we can see full details of vessels in the vicinity to enable identification of the anonymous targets displayed on the radar screens. It also enables a lot of information to be transmitted automatically without the need to communicate it verbally to coastguard stations when entering traffic areas which they are monitoring, this indeed being the main reason it was set up in the first place.
