Global Coverage
The only way to achieve true global coverage is with at least one satellite in a polar orbit (i.e. the satellite travels north/south over the poles on each orbit. Other orbits may cover lower latitudes but have poor coverage at mid to high latitudes. Additional satellites are not added for coverage - they are added to improve how often a satellite passes over a spot on the earth.
The exactEarth constellation of AIS-detecting satellites orbit the earth every 90 to 100 minutes at an altitude of between 650 and 850km above the earth and collect AIS messages transmitted by ships within the satellite field of view. Ships that are underway and equipped with a functioning Class A AIS transponder will transmit many messages in the time duration of an overhead pass of any of the AIS satellites. Additionally, exactAIS™ can also detect messages from Class B transponders when certain conditions are met, such as in areas with a low density of Class A transponders.
Global coverage is essential to many customers. exactEarth's constellation is based on such orbits and can provide global coverage with higher refresh rates today. In future, additional orbital planes will be added to continue to improve refresh rates globally.
Of course, coverage is only effective if the detection rates are adequate.
exactAIS™ is uniquely capable of providing a complete picture of global vessel movements.
