Abstract: A transmission device for multi-frequency equal-amplitude non-harmonic electrical prospecting signal includes a single-chip microcontroller, a field programmable gate array (FPGA), a digital to analog conversion (DAC) module, an isolation amplifier circuit, a differential amplifier module, a digital power amplifier circuit, and a sensor module connected successively. A plurality of output ends of the digital power amplifier circuit is in cascade connection with a grounding electrode A and a grounding electrode B to form a loop with ground. An input end of the sensor module is connected with the digital power amplifier circuit. An output end of the sensor module is connected with the single-chip microcontroller.

Abstract: A device for reducing turn-off time of a transient electromagnetic transmitting signal includes a transmitting coil, a first electronic switch to control connection mode of the transmitting coil and a second electronic switch configured to form a bridge arm. The transmitting coil is a twisted pair including a first wire and a second wire. The first wire is connected to one end of the second electronic switch. The other end of the second electronic switch is connected to one end of the first electronic switch. The other end of the first electronic switch is connected to the second wire. The connection mode of the transmitting coil includes head-to-head connection, head-to-tail connection and tail-to-tail connection between the first wire and the second wire. The first wire and the second wire are connected to form a transmitting loop.

Abstract: A device for reducing turn-off time of a transient electromagnetic transmitting signal includes a transmitting coil, a first electronic switch to control connection mode of the transmitting coil and a second electronic switch configured to form a bridge arm. The transmitting coil is a twisted pair including a first wire and a second wire. The first wire is connected to one end of the second electronic switch. The other end of the second electronic switch is connected to one end of the first electronic switch. The other end of the first electronic switch is connected to the second wire. The connection mode of the transmitting coil includes head-to-head connection, head-to-tail connection and tail-to-tail connection between the first wire and the second wire. The first wire and the second wire are connected to form a transmitting loop.