Extremely low frequency electromagnetic signal transmitter

The invention discloses an extremely-low-frequency electromagnetic signal transmitter, which relates to the technical field of pipeline detection and comprises a single chip microcomputer, a magnetic field transmitting loop, a receiving coil and an iron core. The magnetic field transmitting loop comprises a series resonance loop and a driving circuit, the series resonance loop comprises a transmitting coil, a capacitance network, a resistance network and a current sampling resistor which are connected in series, the driving circuit is connected with the transmitting coil and the single chip microcomputer, and the driving circuit generates an SPWM waveform to drive the series resonance loop; the single-chip microcomputer is used for adjusting parameters of the SPWM waveform. When the magnetic field transmitting loop stops working, the receiving coil receives an external signal, the single chip microcomputer identifies an external control signal from the external signal, and when the magnetic field transmitting