Payload of a satellite intended for monitoring maritime trajectories of ships, and capable of receiving AIS signals, suitable for a ground-based AIS system, and transmitted in the form of bursts from ships (8, 10, 12) at sea, each burst received having a presence or absence of collision, the payload comprising a first transmission chain having: at least two reception antennas (An 1, An 2, An 3, An 4, An 5) tuned to the same predetermined VHF reception band, separated from each other and disposed according to a predetermined geometric configuration with respect to a frame of reference specific to the satellite, each (An 1, An 2, An 3, An 4, An 5) being capable of furnishing at the same time a different output signal (O 1 (t), O 2 (t), O 3 (t) O 4 (t), O 5 (t)) as a function of its respective position in the frame of reference specific to the satellite and corresponding to the same burst received for which the demodulation is sought, at least two receivers (RX 1, RX 2, RX 3, RX 4, RX 5) and at least two analogue/digital converters (CAN 1, CAN 2, CAN 3, CAN 4, CAN 5), each receiver (RX 1, RX 2, RX 3, RX 4, RX 5) not having a useful data AIS signal demodulator and being connected respectively upstream to a specific associated antenna (An 1, An 2, An 3, An 4, An 5) and downstream to a specific associated analogue/digital converter (CAN 1, CAN 2, CAN 3, CAN 4, CAN 5), a mass storage device capable of independently saving each of the AIS output signals received at the same time by the receiving antennas and digitised respectively by the analogue/digital converters (S 1 (t), S 2 (t), S 3 (t), S 4 (t), S 5 (t)), and a first transmitter capable of retransmitting, on a first radio link to the ground, the signals that were digitised and saved independently (S 1 (t), S 2 (t), S 3 (t), S 4 (t), S 5 (t)) in the mass storage device for the purpose of complex processing on the ground, characterised in that it comprises a second transmission chain capable of demodulating each burst received of useful monitoring data, the second transmission chain comprising a second transmitter capable of retransmitting said useful data on a second radio link to the ground; in that the second transmission chain is capable of demodulating the bursts received free of collision and then of retransmitting them immediately to the ground; and in that the mass storage device is capable of independently saving each of the AIS output signals received at the same time by the receiving antennas and digitised (S 1 (t), S 2 (t), S 3 (t), S4(t), S 5 (t)) respectively by the analogue/digital converters (CAN 1, CAN 2, CAN 3, CAN 4, CAN 5), only when the burst whereof the demodulation is sought has a collision, i.e. is affected or has a probability higher than a predetermined threshold of being affected by a collision with another burst. at least two reception antennas (An 1, An 2, An 3, An 4, An 5) tuned to the same predetermined VHF reception band, separated from each other and disposed according to a predetermined geometric configuration with respect to a frame of reference specific to the satellite, each (An 1, An 2, An 3, An 4, An 5) being capable of furnishing at the same time a different output signal (O 1 (t), O 2 (t), O 3 (t) O 4 (t), O 5 (t)) as a function of its respective position in the frame of reference specific to the satellite and corresponding to the same burst received for which the demodulation is sought, at least two receivers (RX 1, RX 2, RX 3, RX 4, RX 5) and at least two analogue/digital converters (CAN 1, CAN 2, CAN 3, CAN 4, CAN 5), each receiver (RX 1, RX 2, RX 3, RX 4, RX 5) not having a useful data AIS signal demodulator and being connected respectively upstream to a specific associated antenna (An 1, An 2, An 3, An 4, An 5) and downstream to a specific associated analogue/digital converter (CAN 1, CAN 2, CAN 3, CAN 4, CAN 5), a mass storage device capable of independently saving each of the AIS output signals received at the same time by the receiving antennas and digitised respectively by the analogue/digital converters (S 1 (t), S 2 (t), S 3 (t), S 4 (t), S 5 (t)), and a first transmitter capable of retransmitting, on a first radio link to the ground, the signals that were digitised and saved independently (S 1 (t), S 2 (t), S 3 (t), S 4 (t), S 5 (t)) in the mass storage device for the purpose of complex processing on the ground, characterised in that it comprises a second transmission chain capable of demodulating each burst received of useful monitoring data, the second transmission chain comprising a second transmitter capable of retransmitting said useful data on a second radio link to the ground; in that the second transmission chain is capable of demodulating the bursts received free of collision and then of retransmitting them immediately to the ground; and in that the mass storage device is capable of independently saving each of the AIS output signals received at the same time by the receiving antennas and digitised (S 1 (t), S 2 (t), S 3 (t), S4(t), S 5 (t)) respectively by the analogue/digital converters (CAN 1, CAN 2, CAN 3, CAN 4, CAN 5), only when the burst whereof the demodulation is sought has a collision, i.e. is affected or has a probability higher than a predetermined threshold of being affected by a collision with another burst.