Satellite AIS

Satellite AIS for Global Vessel Surveillance

Historically, the detection of AIS transmissions was limited by Line Of Sight (LOS) radio wave propagation, and the proximity of AIS surveillance assets, either vessel, airborne or shore based.

Vessels operators and national authorities that wished to identify and monitor vessels at long range (50 NM to Unlimited) were forced to rely on traditional satellite tracking methods. These were expensive to own and operate, and typically were highly collaborative. Access to this data was difficult to obtain unless a commercial agreement was in place, and certain vessel operators were unwilling to be monitored, i.e. fishing trawlers.

In very recent years, various companies have equipped / launched satellites that carry a payload capable of detecting AIS transmissions from space! This means that it is now possible to detect most AIS equipped vessels at great range – without the vessel operator being aware.

SeaTraq’s parent company, IMIS Global, have worked closely with these S-AIS data providers. Under agreement, this data can be incorporated into our MariWeb AIS network management software. All the cutting edge data management features and modules that a terrestrial AIS network could benefit from, can now be applied to vessels operating in some of the most remote waters on the planet.

Typically, access to a specific type of data set can be based on, but not limited to following requirements:

  • A specific area of interest (i.e. Gulf of Aden)
  • By specific vessel/s only (i.e. unique Maritime Mobile Service Identifier), or
  • By vessel type as programmed into its AIS transponder (i.e. Fishing Vessel)
Both Class A and Class B AIS transponders are detectable by S-AIS, however Class A transmissions are more likely to be detected for the following reasons, among others:

  • A Class A transponder has a higher transmit power of 12.5 watt, compared to a Class B at 1-3 watt on average
  • Per minute, a Class A transponder transmits its data more often than Class B, increasing the probability of S-AIS detection of these reports as the satellite passes from horizon to horizon
  • Class A vessels typically have VHF antenna that are dedicated to AIS use, and are positioned much higher above Mean Sea Level (MSL) when compared to Class B vessels

For more information on how you and your organisation can access long range S-AIS data inside our MariWeb AIS network management software, please contact us to discuss your specific requirements.