1. An airborne electromagnetic time domain survey system configured for geophysical prospecting of an underground formation, which airborne electromagnetic survey system comprises:a transmitter arrangement comprising:
at least one current source connected to at least one transmitter coil arrangement covering an area for generating a magnetic moment for building up a primary electromagnetic field inducing a secondary electromagnetic field in the underground formation; and
a switch arrangement comprising at least one switch inserted in between the at least one current source and the at least one transmitter coil arrangement and configured:
to connect the at least one current source with the at least one transmitter coil arrangement to build up a connecting secondary electromagnetic field, which connect is at a connection time at a connection voltage at a connection current; and
to disconnect the at least one current source from the at least one transmitter coil arrangement to build up a disconnecting secondary electromagnetic field; which disconnect is at a disconnection time at a disconnection voltage at a disconnection current resulting in an off-time-period until a next connect; which
connecting secondary electromagnetic field and disconnecting secondary electromagnetic field provide a combined secondary electromagnetic field;
a receiver arrangement comprising at least one receiver coil configured to receive a combination of the connecting and disconnecting secondary electromagnetic fields;
wherein the airborne electromagnetic time domain survey system comprises multiple transmitter arrangements that includes the transmitter arrangement, and wherein the airborne electromagnetic time domain survey system also comprises a switch arrangement controller configured to control switch arrangements of the transmitter arrangements to disconnect each current source from each transmitter coil arrangement at substantially the same time generating individual secondary electromagnetic fields whose sum generates a total secondary electromagnetic field.