Abstract: Provided is a power feeding device capable of performing wireless power feeding at a joint of elongated objects and mitigating a decline in transmission efficiency even through a long elongated object multistage-connected body. A power feeding device 1 includes an elongated object multistage-connected body in which elongated objects 3 each provided with a power feed circuit 30 are connected in multiple stages, wherein the power feed circuit 30 of one elongated object 3 is provided with a power-receiving coil 31 which wirelessly receives power from the power feed circuit 30 of another elongated object 3, a power feed line 32, and a power-transmitting coil 33 which wirelessly transmits power to the power feed circuit 30 of another elongated object 3, and the plurality of power feed circuits 30 constitute a periodic circuit.

Abstract: A transmission apparatus is a transmission apparatus that generates a pressure wave for transmitting data in drilling mud, and includes a tubular member, a plurality of valves that are provided side by side in an axial direction of the tubular member inside the tubular member, each of which includes a stator including holes for passing the drilling mud, and a rotatable rotor which is provided to overlap the stator and includes blocking portions blocking the holes in the stator according to a rotation position, a motor that rotates the respective rotors, and a control unit that controls the motor 130 so as to rotate and stop the respective rotors at frequencies different from each other, according to data to be transmitted.

Abstract: A transmission apparatus is a transmission apparatus that generates a pressure wave for transmitting data in drilling mud, and includes a tubular member, a plurality of valves that are provided side by side in an axial direction of the tubular member inside the tubular member, each of which includes a stator including holes for passing the drilling mud, and a rotatable rotor which is provided to overlap the stator and includes blocking portions blocking the holes in the stator according to a rotation position, a motor that rotates the respective rotors, and a control unit that controls the motor 130 so as to rotate and stop the respective rotors at frequencies different from each other, according to data to be transmitted.