Originally postedby Machinbird;
I suspect that there may be a misunderstanding of what AIS can do.
I believe you may have misinterpreted
Broadreach's post.
- Broadreach has particularly been seeking AIS position reporting through satellite data acquisition.
- Broadreach provided me with the twice daily positions of the "Seabed Worker" and the "Anne Candies" during the Phase 3 search.
- Most administrations require that ships report their positions twice daily, and those same reports are acquired by Lloyds Intelligence.
- Depending on a the web based provider's access to AIS data obtained by local terrestrial receiving stations, users of those web based products will be able to see plots of ships within range of each station.
- Real-time satellite data packages are available as a small clip-on to the existing terrestrial packages, and can be programed to supply data as required to a specified end-user, e.g. continuously, or periodically via Low Earth Orbiting (LEO) satellites.
Generally, the transmission of the marine Automatic Identification System data on both of the marine VHF channels 87B (161.975 MHz) and 88B (162.025 MHz is mandatory for vessels of 300 gross registered tons and over. Exceptions are notably for naval vessels, and at the master's discretion, e.g. when the transmission of positional information may lead to the vessel being intercepted by pirates.
Note :: The designed for use of AIS is as a collision avoidance system, whereby shipboard plotters display the relevant position, track, speed and rate of turn data, along with vessel identification and size of those vessels within VHF range of their ship. In other words it is the marine version of aeronautical secondary radar, but instead of being land-based, is ship-based - TCAS style.
This
Wikipedia article is comprehensive and up to date.