Flux Orientation Locating in a Drilling System

Abstract

An above ground locator includes an apparatus for determining the strength of the locating signal at a selected point relative to the boring tool. The apparatus includes an antenna arrangement configured for measuring the strength of the locating signal at the selected point along first and second orthogonally opposed receiving axes to produce first and second received signals. A phase shifting arrangement phase shifts the first and second received signals in a predetermined way to generate first and second phase shifted signals, respectively. Thereafter, a summing arrangement adds the first and second phase shifted received signals to generate an output signal which is a vector sum of the first and second received signals. In one feature, third and fourth signals derived from the first and second signals are used to eliminate balance point ambiguity which is present using the first and second signals alone. In another feature, signals corresponding to first, second, third and fourth axes are compared in a way which confines the possible locations of an above ground point to one particular type of region out of a plurality of different types of regions. Tracking of the boring tool may be accomplished in a number of described ways since the regions occur in a specific sequence along the intended path with respect to the location of the boring tool.

1 . In a technique for at least partially establishing a positional relationship with respect to a transmitter configured for transmitting a dipole field, a method comprising:
 positioning the transmitter at a depth below the surface of the ground in an orientation which at least generally establishes a particular pattern of magnetic fluxlines in relation to the surface of the ground, such that fore and aft signal points are defined as part of said particular pattern, each of said fore and aft signal points having a flux orientation which is normal to the surface of the ground, and which particular pattern relates in certain ways to a current position of the transmitter as characterized by a localized slope of the fluxlines relative to the surface of the ground; and   moving an antenna arrangement, that is responsive to the localized slope of the fluxlines, through the particular pattern in relation to the surface of the ground to monitor the localized slope of the fluxlines for use in generating directional indications relating to the current position of the transmitter from a current position of the antenna arrangement.   
   
   
       2 . The method of  claim 1  further comprising:
 generating at least one directional indication and displaying the directional indication.   
   
   
       3 . In a system for at least partially establishing a positional relationship, an apparatus comprising:
 a transmitter positioned for transmitting a dipole field at a depth below the surface of the ground in an orientation which at least generally establishes a particular pattern of magnetic fluxlines in relation to the surface of the ground, such that fore and aft signal points are defined as part of said particular pattern, each of said fore and aft signal points having a flux orientation which is normal to the surface of the ground, and which particular pattern relates in certain ways to a current position of the transmitter as characterized by a localized slope of the fluxlines relative to the surface of the ground; and   an antenna arrangement, that is responsive to the localized slope of the fluxlines, configured for movement through the pattern in relation to the surface of the ground to monitor the localized slope of the fluxlines for use in generating directional indications relating to the current position of the transmitter from a current position of the antenna arrangement.   
   
   
       4 . In a technique for at least partially establishing a positional relationship with respect to a transmitter configured for transmitting a dipole field, a method comprising:
 positioning the transmitter at a depth below the surface of the ground in an orientation which at least generally establishes a particular pattern of magnetic fluxlines in relation to the surface of the ground, such that fore and aft signal points are defined as part of said particular pattern, each of said fore and aft signal points having a flux orientation which is normal to the surface of the ground, and which particular pattern relates in certain ways to a current position of the transmitter as characterized by a localized slope of the fluxlines relative to the surface of the ground; and   moving an antenna arrangement, that is responsive to the localized slope of the fluxlines, through the particular pattern in relation to the surface of the ground to monitor the localized slope of the fluxlines for use in generating directional indications relating to a current position of at least one of the fore and aft signal points for the current position of the transmitter from a current position of the antenna arrangement.   
   
   
       5 . In a system for at least partially establishing a positional relationship with respect to a transmitter configured for transmitting a dipole field, an apparatus comprising:
 a transmitter positioned at a depth below the surface of the ground in an orientation which at least generally establishes a particular pattern of magnetic fluxlines in relation to the surface of the ground, such that fore and aft signal points are defined as part of said particular pattern, each of said fore and aft signal points having a flux orientation which is normal to the surface of the ground, and which particular pattern relates in certain ways to a current position of the transmitter as characterized by a localized slope of the fluxlines relative to the surface of the ground; and   an antenna arrangement, that is responsive to the localized slope of the fluxlines, configured for movement through the pattern in relation to the surface of the ground to monitor the localized slope of the fluxlines for use in generating directional indications relating to a current position of at least one of the fore and aft signal points for the current position of the transmitter from a current position of the antenna arrangement.   
   
   
       6 . The apparatus of  claim 5  further comprising:
 a display for displaying said directional indications.