Transient electromagnetic field detection apparatus having dynamic emission source in combination with static emission source and transient electromagnetic field detection method for discovering unexploded ordnance

A detection method for discovering an unexploded ordnance, comprising:

• surrounding a detection region with a transmitting coil and surrounding a detection site in the detection region with a second receiving coil;
• conducting the transmitting coil with a second electric current to transmit a second detecting signal to the detection region;
• respectively acquiring a plurality of second feedback signals at a plurality of second feedback time points, the second feedback signals being second induced electromotive force signals of the second receiving coil;
• partitioning the transmitting coil into a plurality of dipoles, and acquiring a plurality of distance values r respectively between the plurality of dipoles and the detection site;
• respectively calculating feedback depths according to feedback time periods, the feedback time periods being periods of time between the second feedback time points and an initial time point of the conducting the transmitting coil with the second electric current;
• respectively calculating apparent resistivity values corresponding to the feedback depths on the basis of the second feedback signals, the feedback time periods, the distance values r, and the second electric current;
• obtaining an apparent resistivity distribution in depth at the detection site according to the apparent resistivity values and the feedback depths;
• and
• judging whether there is any unexploded ordnance at the detection site according to the apparent resistivity distribution in depth.