Abstract: Discriminating between a cable locating signal and a false cable locating signal is described. A reference signal, which contains a locating signal frequency impressed on it, is transmitted in a way which provides for detection of a phase shift between the locating signal and the false locating signal. Based on the phase shift, a receiver is used to distinguish the locating signal from the false locating signal.

Abstract: An apparatus monitors a positional relationship between a boring tool and an inground line and includes a transmitter to generate a magnetic locating field from one of either the boring tool or at least an underground length of the line. A receiver can be carried by the boring tool if the field is generated from the line, or connected to the line if the field is generated from the boring tool, to detect an intensity of the magnetic locating field to produce a signal indicative of the magnetic field intensity with the signal being responsive to the positional relationship between the boring tool and the line. A display produces an indication responsive to the signal based on the detected intensity of the magnetic locating field.

Abstract: A drive train is used at least including an input shaft and an output shaft. A clutch member is rotatable by a clutch shaft about an axis of rotation. The clutch shaft is supported for lateral movement along the axis of rotation to move the clutch member to cooperate with the drive train at a first lateral position to cause the output shaft to turn and to move the clutch member to a second lateral position to disengage the output shaft from rotation of the input shaft. A permanent magnet is supported by one end of the clutch shaft and arranged for receiving an external magnetic biasing force along the axis of rotation to selectively move the clutch member between the first and second lateral positions. A traveling shaft can be used to support a selected gear for movement by the permanent magnet to implement transmission and reversing configurations.

Abstract: Location determination is performed using a transmitter including an elongated generally planar loop antenna defining an elongation axis. The elongation axis is positioned along at least a portion of a path. A magnetic field is then generated which approximates a dipole field. Certain characteristics of the magnetic field are then determined at a receiving position radially displaced from the antenna elongation axis. Using the determined certain characteristics, at least one orientation parameter is established which characterizes a positional relationship between the receiving position and the antenna on the path. The magnetic field may be transmitted as a monotone single phase signal. The orientation parameter may be a radial offset and/or an angular orientation between the receiving position and the antenna on the path. The antenna of the transmitter may be inserted into a first borehole to transmit the magnetic field to a receiver inserted into a second borehole.

Abstract: A transmitter transmits a locating signal from a boring tool by operating at a frequency that is selected as one of at least two operating frequencies for use in locating the boring tool. A receiver, forming part of the locator, cooperates with the locator to cause the locator to respond dynamically to a change of the selected one of the operating frequencies such that the locator tracks the selected operating frequency.

Abstract: An arrangement and an associated method are described in which a boring tool is moved through the ground within a given region along a path in which region a cable is buried. The boring tool and the cable transmit a boring tool locating signal and a cable locating signal, respectively. Intensities of the boring tool locating signal and the cable locating signal are measured along with a pitch orientation of the boring tool. Using the measured intensities and established pitch orientation, a positional relationship is determined to relative scale including at least the boring tool and the cable in the region. The positional relationship is displayed to scale in one view. The positional relationship may be determined and displayed including the forward locate point in scaled relation to the boring tool and the cable. Cable depth determination techniques are described including a two-point ground depth determination method.

Abstract: A device rotates at least one static magnetic field about an axis, producing a rotating magnetic dipole field, and is movable in relation to the surface of the ground. The field is periodically sensed using a receiver to produce a receiver output responsive to the field. A positional relationship between the receiver and the device is monitored using the output. In one aspect, changing the positional relationship, by moving the device nearer to a boring tool which supports the receiver, causes an increase in accuracy of depth determination. In another aspect, determination of an actual overhead position of the boring tool, and its application, are described. Use of a plurality of measurements over at least one-half revolution of each magnet is disclosed. Establishing a surface radial direction toward a boring tool and resolution of multi-valued parameters is described. Calibration techniques, as well as a three transmitter configuration are also described.

Abstract: A portable locator and method for establishing the location of the cable line in a region which includes at least one generally straight electrically conductive cable line extending across the region from which cable line a locating signal includes a first arrangement for measuring a local flux intensity of the locating signal at a first above ground point within the region with the portable locator in a particular orientation at the first above ground point. A second arrangement uses the local flux intensity to establish a cable line angular orientation which limits the possible directions to the cable line relative to the particular orientation of the portable locator at the above ground point. A third arrangement uses the measured local flux intensity to establish an actual direction of the cable line that is selected from the possible directions based on certain characteristics of the locating signal.

Abstract: A steering tool is movable by a drill string to form an underground bore along an intended path. A sensing arrangement of the steering tool detects its pitch and yaw orientations at a series of spaced apart positions along the bore, each position is characterized by a measured extension of the drill string. The steering tool further includes a receiver. At least one marker is positioned proximate to the intended path, for transmitting a rotating dipole field to expose a portion of the intended path to the field for reception by the receiver. The detected pitch orientation, the detected yaw orientation and the measured extension of the drill string are used in conjunction with magnetic information from the receiver to locate the steering tool. The steering tool may automatically use the magnetic information when it is available. A customized overall position determination accuracy can be provided along the intended path.

Abstract: Specific apparatus and associated methods are described for use in establishing the positions of locating field detectors and for path mapping within a region for the purpose of tracking and/or guiding the movement of an underground boring tool. In one aspect, an improvement is provided forming part of an arrangement for tracking the position and/or guiding the boring tool using an electromagnetic locating signal which is transmitted from the boring tool as the boring tool moves through the ground. At least two detectors are located at fixed positions within the region, each being operable in a transmit mode and in a receive mode such that each one of the detectors in the transmit mode is able to transmit a relative locating signal to the other detector for use in determining the relative position of one detector in relation to the other and such that both detectors receive the electromagnetic locating signal in the receive mode for use in determining the position of the boring tool within the region.

Abstract: A device is described for use as part of a system in which a transmitter is moved through the ground while transmitting a signal that can be used to locate the transmitter. The device includes a receiver for receiving the signal to generate certain information about the position of the transmitter relative to the position of the device based on the signal. A processor establishes a current location of the transmitter and records the current location as one of a series of recorded locations of the transmitter based on the certain information and, at a time of recording the current location, electronically records a time stamp that designates at least the time at which the current location was recorded as part of the series of recorded locations of the transmitter.

Abstract: A boring tool moves having a pitch orientation, a yaw orientation and a roll orientation and is steerable underground using the roll orientation. A maximum drill string curvature is established for steering. The boring tool is advanced over a path segment. An averaged roll characteristic is determined for movement of the boring tool along the path segment. A path segment pitch orientation is established based on at least one measured pitch orientation along the path segment. Using the maximum drill string curvature in combination with the averaged roll characteristic and the path segment pitch orientation, the yaw orientation is determined. The averaged roll characteristic is determined based on a series of incremental roll measurements that are spaced across the path segment. A set of coupled ordinary differential equations is used to characterize movement of the boring tool.

Abstract: A method is described for use in a region which contains at least first and second in-ground cables, each of which cables includes an electrically conductive component such that, when the first cable is driven at a locating signal frequency to emit a locating signal in an electromagnetic form, the locating signal can be coupled to the second cable in a way which causes the second cable to generate a false locating signal in electromagnetic form. The locating signal is received along with the false locating signal as well as receiving a reference signal which contains the locating signal frequency impressed thereon. The locating signal is distinguished from the false locating signal based on the locating signal frequency as contained by the reference signal.

Abstract: Location determination is performed using a transmitter including an elongated generally planar loop antenna defining an elongation axis. The elongation axis is positioned along at least a portion of a path. A magnetic field is then generated which approximates a dipole field. Certain characteristics of the magnetic field are then determined at a receiving position radially displaced from the antenna elongation axis. Using the determined certain characteristics, at least one orientation parameter is established which characterizes a positional relationship between the receiving position and the antenna on the path. The magnetic field may be transmitted as a monotone single phase signal. The orientation parameter may be a radial offset and/or an angular orientation between the receiving position and the antenna on the path. The antenna of the transmitter may be inserted into a first borehole to transmit the magnetic field to a receiver inserted into a second borehole.

Abstract: A device rotates at least one static magnetic field about an axis, producing a rotating magnetic dipole field, and is movable in relation to the surface of the ground. The field is periodically sensed using a receiver to produce a receiver output responsive to the field. A positional relationship between the receiver and the device is monitored using the output. In one aspect, changing the positional relationship, by moving the device nearer to a boring tool which supports the receiver, causes an increase in accuracy of depth determination. In another aspect, determination of an actual overhead position of the boring tool, and its application, are described. Use of a plurality of measurements over at least one-half revolution of each magnet is disclosed. Establishing a surface radial direction toward a boring tool and resolution of multi-valued parameters is described. Calibration techniques, as well as a three transmitter configuration are also described.

Abstract: The flight of an aircraft is characterized in terms of Earth-based reference system data for a first position and a second position of the aircraft that are separated by a time increment. A centripetal acceleration of the aircraft is determined based on the Earth-based reference system data for the positions in conjunction with the time increment. A rate of rotation is established corresponding to the time increment in an aircraft-based reference system. Aircraft airspeed is determined based on the centripetal acceleration and the rate of rotation. A turn can be detected as characterized by a change in track angle from a prior GPS packet compared to a new packet. Aircraft turns can be detected based on a change in track angle in GPS packets. Compensation can be applied to a gyro based on centripetal acceleration such that the gyro more accurately responds to the Earth gravity axis.

Abstract: A portable locator and method for establishing the location of the cable line in a region which includes at least one generally straight electrically conductive cable line extending across the region from which cable line a locating signal includes a first arrangement for measuring a local flux intensity of the locating signal at a first above ground point within the region with the portable locator in a particular orientation at the first above ground point. A second arrangement uses the local flux intensity to establish a cable line angular orientation which limits the possible directions to the cable line relative to the particular orientation of the portable locator at the above ground point. A third arrangement uses the measured local flux intensity to establish an actual direction of the cable line that is selected from the possible directions based on certain characteristics of the locating signal.

Abstract: An arrangement and an associated method are described in which a boring tool is moved through the ground within a given region along a path in which region a cable is buried. The boring tool and the cable transmit a boring tool locating signal and a cable locating signal, respectively. Intensities of the boring tool locating signal and the cable locating signal are measured along with a pitch orientation of the boring tool. Using the measured intensities and established pitch orientation, a positional relationship is determined to relative scale including at least the boring tool and the cable in the region. The positional relationship is displayed to scale in one view. The positional relationship may be determined and displayed including the forward locate point in scaled relation to the boring tool and the cable. Cable depth determination techniques are described including a two-point ground depth determination method.

Abstract: Specific apparatus and associated methods are described for use in establishing the positions of locating field detectors and for path mapping within a region for the purpose of tracking and/or guiding the movement of an underground boring tool. In one aspect, an improvement is provided forming part of an arrangement for tracking the position and/or guiding the boring tool using an electromagnetic locating signal which is transmitted from the boring tool as the boring tool moves through the ground. At least two detectors are located at fixed positions within the region, each being operable in a transmit mode and in a receive mode such that each one of the detectors in the transmit mode is able to transmit a relative locating signal to the other detector for use in determining the relative position of one detector in relation to the other and such that both detectors receive the electromagnetic locating signal in the receive mode for use in determining the position of the boring tool within the region.

Abstract: A steering tool is movable by a drill string to form an underground bore along an intended path. A sensing arrangement of the steering tool detects its pitch and yaw orientations at a series of spaced apart positions along the bore, each position is characterized by a measured extension of the drill string. The steering tool further includes a receiver. At least one marker is positioned proximate to the intended path, for transmitting a rotating dipole field to expose a portion of the intended path to the field for reception by the receiver. The detected pitch orientation, the detected yaw orientation and the measured extension of the drill string are used in conjunction with magnetic information from the receiver to locate the steering tool. The steering tool may automatically use the magnetic information when it is available. A customized overall position determination accuracy can be provided along the intended path.