Ships detected each day by AISSat-1 and -2 (left) and by NorSat-1 and 2 (right) in the North Sea.
The colour code shows how many times each ship has been observed during the observation period of 24 hours (red->yellow: fewer observations, green->blue: more observations).
In areas with heavy maritime traffic the number of messages sent by ships can be so high that they jam the satellite receiver. The solution is a new type of message that is more easily picked up by satellites and suffers less interference from other messages.
The total number of messages from the NorSat receivers typically reach 2.5 million per day. This is nearly three times more than the previous receivers on AISSat-1 and 2, which together achieved about 900 000 per day.