Homing system for an in-ground boring device

Claim 1

A homing system (10) for an in-ground boring device (12) for directing the device (12) through the ground from its particular location at a given point (14) to a specific in-ground target point (16), comprising means (22) including a transmitting antenna carried by said boring device (12) for producing a near full electromagnetic dipole field containing a predetermined homing signal, and means (26) including a receiving antenna (30) located at a ground level point (28) directly above or beyond said target point (16) for detecting said homing signal and for producing its own internal signal containing information which indicates whether the horizontal component of movement of the boring device (12) is on or off a particular course leading to said target point (16) and, if the boring device (12) is off said course, whether its horizontal component of movement is headed to the left or right of the course with respect to the target point (16), characterised by means (32) including a transmitting antenna located at said ground level point (28) and responsive to said internal signal for transmitting by electromagnetic waves to a remote location (18) a control signal containing said information; and control means located in part at said remote location (18) and in part on the boring device (12) and responsive to said control signal for steering the boring device (12) on a course to said target point (16).

Claim 6

A system according to any preceding claim, characterised in that said electromagnetic dipole field is produced at no more than about one watt of power.

Claim 7

A system according to any preceding claim, characterised in that said homing signal has a frequency of between about 80 and 90 KHz..

Claim 8

A system according to any preceding claim, characterised in that said boring device (12) is between 15 and 30 cms (6 and 12 inches) long and about 7.5 cms (3 inches) wide.

Claim 9

A system according to any preceding claim, characterised in that said control signal establishes the horizontal component of movement of the boring device (12) as it is steered to said target point (16) by said control means, and in that said control means also includes means for establishing the vertical component of movement of the boring device (12) as it moves to said target point (16).

Claim 10

A system according to any preceding claim, characterised in that said receiving antenna (30) is configured so that the information contained in said internal signal indicates not only whether the boring device (12) is on or off a course leading to said target point (16) but also the magnitude by which it is off course.

Claim 13

A method of homing an in-ground boring device through the ground from its particular location at a given point to a specific in-ground target point, comprising the steps of generating from said boring device a near full electromagnetic dipole field containing a predetermined homing signal; and at a ground level location directly above or beyond said target point, detecting said homing signal by means of a receiving antenna and producing an internal signal containing information which indicates whether the horizontal component of movement of the boring device is on or off a particular course leading to said target point, and if the boring device is off said course, whether its horizontal component of movement is headed to the left or right of the course with respect to the target point, characterised by the steps of, in response to said internal signal, producing at said ground level point a control signal containing said information, and transmitting said control signal by electromagnetic waves to a remote location; and responding to said control signal at said remove location for steering said boring device on a course to said target point.

Claim 14

A method of homing an in-ground boring device through the ground from its particular location at a given point to a specific in-ground target point, comprising the steps of generating from said boring device a near full electromagnetic dipole field containing a predetermined homing signal; and at a ground level location directly above or beyond said target point, detecting said homing signal by means of a receiving antenna and producing an internal signal containing information which indicates whether the horizontal component of movement of the boring device is on or off a particular course leading to said target point, and if the boring device is off said course, whether its horizontal component of movement is headed to the left or right of the course with respect to the target point, characterised by the steps of, in response to said internal signal, producing at said ground level point a control signal containing said information, and transmitting said control signal by electromagnetic waves to a remote location; and responding to said control signal at said remove location for steering said boring device on a course to said target point.