Borehole signalling by acoustic energy

Claim 2

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting said carrier comprising a signal receiver, a tunable input circuit receptive of the signal receiver output, a tunable output circuit, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 and to tune said output circuit to frequency f2.

Claim 3

Repeater according to claim 1, wherein said means also acts, in response to the receipt by said receiver of carrier frequency f2, to tune said input circuit to frequency f2 and to tune said output circuit to frequency f1.

Claim 4

A signal transmission system for use in a borehole, comprising, at a location A: a sound source acoustically coupled to the drill pipe in said borehole for transmitting an acoustic carrier wave along such pipe, and means supplying to said source wave energy periodically shifted back and forth between two frequencies f1 and f 2, thereby to transmit along the drill pipe an acoustic carrier wave periodically shifted back and forth between frequencies f1 and f2; and at a location B spaced a pre-established distance along said drill pipe from location A: a sound pickup acoustically coupled to the drill pipe, a tunable input circuit receptive of the sound pickup output, and means acting upon the receipt by said pickup of carrier frequency f1 to tune said input circuit to frequency f1.

Claim 5

A signal transmission system for use in a borehole, comprising, at a location A: a sound source acoustically coupled to the drill pipe in said borehole for transmitting an acoustic carrier wave along such pipe, and means supplying to said source wave energy periodically shifted back and forth between two frequencies f1 and f 2, thereby to transmit along the drill pipe an acoustic carrier wave periodically shifted back and forth between frequencies f1 and f2; and at a location B spaced a pre-established distance along said drill pipe from location A: a sound pickup acoustically coupled to the drill pipe, a tunable input circuit receptive of the sound pickup output, and means acting upon the receipt by said pickup of carrier frequency f1 to tune said input circuit to frequency f1.

Claim 6

System set forth in claim 3, wherein said means at location B also acts, upon the receipt by said pickup of carrier frequency f2, to tune said input circuit to frequency f2.

Claim 7

System according to claim 3, wherein the distance between location A and location B is known, and wherein the frequency shifts of the transmitted carrier wave are separated by time intervals equal to twice the acoustic transit time, in the drill pipe, for such known distance.

Claim 8

System of claim 3, including also, at location B, a tunable output circuit associated with said input circuit, and a sound transmitter acoustically coupled to the drill pipe and driven from said output circuit; said means at location B acting also, upon the receipt by said pickup of carrier frequency f1, to tune said output circuit to frequency f2.

Claim 9

System set forth in claim 6, wherein said means at location B also acts, upon the receipT by said pickup of carrier frequency f2, to tune said output circuit to frequency f1.

Claim 10

System set forth in claim 7, wherein the distance between location A and location B is known, and wherein the frequency shifts of the transmitted carrier wave are separated by time intervals equal to twice the acoustic transit time, in the drill pipe, for such known distance.

Claim 11

A signal transmission system for boreholes, comprising a command signal generator located at one end of a string of drill pipe, and a plurality of identical repeaters in said pipe string spaced from said generator and from each other, said repeaters being spaced at known, uniform distances from each other along the length of said string; said command signal generator including means for transmitting along said string a continuous acoustic carrier which is periodically shifted back and forth between two frequencies f1 and f2; each of said repeaters including a sound pickup acoustically coupled to the drill pipe, a tunable input circuit receptive of its respective sound pickup output, a tunable output circuit, a sound transmitter acoustically coupled to the drill pipe and driven from its respective output circuit, and means acting upon the receipt by each pickup of carrier frequency f1 to tune its respective input circuit to frequency f1 and to tune its respective output circuit to frequency f1.

Claim 12

A signal transmission system for boreholes, comprising a command signal generator located at one end of a string of drill pipe, and a plurality of identical repeaters in said pipe string spaced from said generator and from each other, said repeaters being spaced at known, uniform distances from each other along the length of said string; said command signal generator including means for transmitting along said string a continuous acoustic carrier which is periodically shifted back and forth between two frequencies f1 and f2; each of said repeaters including a sound pickup acoustically coupled to the drill pipe, a tunable input circuit receptive of its respective sound pickup output, a tunable output circuit, a sound transmitter acoustically coupled to the drill pipe and driven from its respective output circuit, and means acting upon the receipt by each pickup of carrier frequency f1 to tune its respective input circuit to frequency f1 and to tune its respective output circuit to frequency f1.

Claim 13

System according to claim 9, wherein the means in each repeater also acts, upon the receipt by its pickup of carrier frequency f2, to tune its respective input circuit to frequency f2 and to tune its respective output circuit to frequency f1.

Claim 14

System according to claim 9, wherein the frequency shifts of the carrier transmitted by said command signal generator are separated by time intervals equal to the quotient: twice the inter-repeater spacing, divided by the acoustic velocity in the drill pipe.

Claim 15

System according to claim 9, wherein each of the repeater input circuits is an active filter, and each of the repeater output circuits is an active filter.

Claim 16

System of claim 9, wherein each of said repeaters also includes a shift frequency heterodyne oscillator connected to heterodyne with the output of the respective input circuit to provide a sideband frequency for application to the respective output circuit, the frequency of the oscillator in each repeater being equal to the difference between f1 and f2.

Claim 17

System according to claim 9, wherein each of the repeater input circuits is an active filter whose center frequency depends on the value of an impedance coupled thereto, and wherein the means in each repeater changes the effective value of the corresponding input active filter impedance.

Claim 18

System according to claim 9, wherein each of the repeater input circuits and each of the repeater output circuits is an active filter whose center frequency depends on the value of an impedance coupled respectively thereto, and wherein the means in each repeater changes the effective values of the impedances in the corresponding input and output active filters.

Claim 19

System of claim 9, wherein each of said repeaters also includes a phase-locked loop connected between the repeater output circuit and the repeater sound transmitter and including a voltage-controlled oscillator together with means for locking its frequency to that of the repeater output circuit output; the means in each repeater also acting upon the receipt of carrier frequency f2 to shift the center of the phase-locked loop capture range to frequency f1.

Claim 20

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting said carrier comprising a signal receiver, a tunable input circuit receptive of the signal receiver output, a shift frequency hEterodyne oscillator connected to heterodyne with the output of said input circuit, the frequency of said oscillator being equal to the difference between f1 and f2, a tunable output circuit, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 and to tune said output circuit to frequency f2.

Claim 21

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting said carrier comprising a signal receiver, a tunable input circuit receptive of the signal receiver output, a shift frequency hEterodyne oscillator connected to heterodyne with the output of said input circuit, the frequency of said oscillator being equal to the difference between f1 and f2, a tunable output circuit, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 and to tune said output circuit to frequency f2.

Claim 22

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting said carrier comprising a signal receiver, a tunable input circuit comprising an active filter receptive of the signal receiver output, a tunable output circuit comprising an active filter, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 and to tune said output circuit to frequency f2.

Claim 23

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting said carrier comprising a signal receiver, a tunable input circuit comprising an active filter receptive of the signal receiver output, a tunable output circuit comprising an active filter, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 and to tune said output circuit to frequency f2.

Claim 24

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting said carrier comprising a signal receiver, a tunable input circuit comprising an active filter receptive of the signal receiver output and whose center frequency depends on the value of an impedance coupled thereto, a tunable output circuit, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 by changing the effective value of said impedance in said input circuit and to tune said output circuit to frequency f2.

Claim 25

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting said carrier comprising a signal receiver, a tunable input circuit comprising an active filter receptive of the signal receiver output and whose center frequency depends on the value of an impedance coupled thereto, a tunable output circuit, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 by changing the effective value of said impedance in said input circuit and to tune said output circuit to frequency f2.

Claim 26

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting and carrier comprising a signal receiver, a tunable input circuit comprising an active filter whose center frequency depends upon the value of an impedance coupled thereto, said input circuit being receptive of the signal transmitter output, a tunable output carrier comprising an active filter whose center frequency depends upon the value of an impedance coupled thereto, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 and to tune said output circuit to frequency f2 by changing the effective values of said impedance.

Claim 27

In a signal transmission system utilizing a continuous carrier which is periodically shifted back and forth between two frequencies f1 and f2: a repeater arrangement for receiving and retransmitting and carrier comprising a signal receiver, a tunable input circuit comprising an active filter whose center frequency depends upon the value of an impedance coupled thereto, said input circuit being receptive of the signal transmitter output, a tunable output carrier comprising an active filter whose center frequency depends upon the value of an impedance coupled thereto, a signal transmitter coupled to and driven from said output circuit, and means, acting in response to the receipt by said receiver of carrier frequency f1, to tune said input circuit to frequency f1 and to tune said output circuit to frequency f2 by changing the effective values of said impedance.

Claim 28

A signal transmission system for use in a borehole, comprising, at a location A: a sound source acoustically coupled to the drill pipe in said borehole for transmitting an acoustic carrier wave along such pipe, and means supplying to said source wave energy periodically shifted back and forth between two frequencies f1 and f2, thereby to transmit along the drill pipe an acoustic carrier wave periodically shifted back and forth between frequencies f1 and f2: and at a location B spaced a pre-established distance along said drill pipe from location A: a sound pick-up acoustically coupled to the drill pipe, a tunable input circuit comprising an active filter receptive of the sound pick-up output, a tunable output circuit comprising an active filter associated with said input circuit, a sound transmitter acoustically coupled to the drill pipe and driven from the said output circuit, and means acting upon the receipt by said pick-up of carrier frequency f1 to tune said input circuit to frequency f1 and said output circuit to frequency f2, and upon receipt of carrier frequency f2 to tune said input circuit to frequency f2 and said output circuit to frequency f1.

Claim 29

A signal transmission system for use in a borehole, comprising, at a location A: a sound source acoustically coupled to the drill pipe in said borehole for transmitting an acoustic carrier wave along such pipe, and means supplying to said source wave energy periodically shifted back and forth between two frequencies f1 and f2, thereby to transmit along the drill pipe an acoustic carrier wave periodically shifted back and forth between frequencies f1 and f2: and at a location B spaced a pre-established distance along said drill pipe from location A: a sound pick-up acoustically coupled to the drill pipe, a tunable input circuit comprising an active filter receptive of the sound pick-up output, a tunable output circuit comprising an active filter associated with said input circuit, a sound transmitter acoustically coupled to the drill pipe and driven from the said output circuit, and means acting upon the receipt by said pick-up of carrier frequency f1 to tune said input circuit to frequency f1 and said output circuit to frequency f2, and upon receipt of carrier frequency f2 to tune said input circuit to frequency f2 and said output circuit to frequency f1.

Claim 30

A signal transmission system for use in a borehole, comprising, at a location A: a sound source acoustically coupled to the drill pipe in said borehole for transmitting an acousicc carrier wave along such pipe, and means supplying to said source wave energy periodically shifted back and forth between two frequencies f1 and f2, thereby to transmit along the drill pipe an acoustic carrier wave periodically shifted back and forth between frequencies f1 and f2; and at a location B spaced a pre-established distance along said drill pipe from location A: a sound pick-up acoustically coupled to the drill pipe, a tunable input circuit receptive of the sound pick-up output, a tunable output circuit associated with said input circuit, a sound transmitter acoustically coupled to the drill pipe and driven from said output circuit, means acting upon the receipt of said pick-up of carrier frequency f1 to tune said input circuit to frequency f1 and said output circuit to frequency f2, and upon receipt of carrier frequency f2 to tune said input circuit to frequency f2 and said output circuit to frequency f1, and a shift frequency heterodyne oscillator connected to heterodyne with the output of said input circuit to provide a sideband frequency for application to said output circuit, the frequency of said oscillator being equal to the difference between f1 and f2.

Claim 31

A signal transmission system for use in a borehole, comprising, at a location A: a sound source acoustically coupled to the drill pipe in said borehole for transmitting an acousicc carrier wave along such pipe, and means supplying to said source wave energy periodically shifted back and forth between two frequencies f1 and f2, thereby to transmit along the drill pipe an acoustic carrier wave periodically shifted back and forth between frequencies f1 and f2; and at a location B spaced a pre-established distance along said drill pipe from location A: a sound pick-up acoustically coupled to the drill pipe, a tunable input circuit receptive of the sound pick-up output, a tunable output circuit associated with said input circuit, a sound transmitter acoustically coupled to the drill pipe and driven from said output circuit, means acting upon the receipt of said pick-up of carrier frequency f1 to tune said input circuit to frequency f1 and said output circuit to frequency f2, and upon receipt of carrier frequency f2 to tune said input circuit to frequency f2 and said output circuit to frequency f1, and a shift frequency heterodyne oscillator connected to heterodyne with the output of said input circuit to provide a sideband frequency for application to said output circuit, the frequency of said oscillator being equal to the difference between f1 and f2.