Apparatus for determining the distance to a concealed conductive structure

• US 3,893,025 A
• Filed: 02/01/1974
• Issued: 07/01/1975
• Est. Priority Date: 02/01/1974
• Status: Expired due to Term

• Current Assignee: Thomas G. Humphreys Jr
• Original Assignee: Thomas G. Humphreys Jr
• Inventors: Humphreys, Thomas G. Jr.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US05/438,939
• Time in Patent Office: 515 Days
• Field of Search: 324/1,3-8,67
• US Class Current: 324/326
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12

Abstract

A device for locating concealed conductive structures in both horizontal and vertical planes wherein depth measurements are accomplished by a comparison of the signal outputs from two vertically spaced antennas which are energized by a signal radiated from a buried or otherwise concealed object.

Claims

1. A locator for determining the distance to a concealed conductive object lying along a known direction and wherein the object is radiating an alternating current signal, said locator comprising:

first and second signal receptors, each being adapted to receive said signal and provide an output voltage in proportion to the level of said signal as received;

support means for positioning said receptors a selected and fixed distance apart whereby one receptor may be positioned a selected distance greater than the other from said object;

signal combining means, including adjustment means, coupled to the outputs of said receptors for adjustably combining said outputs in a subtractive mode and providing a combined signal output which is reducible to a substantially zero level as a function of setting of said adjustment means;

detection means responsive to the output of said signal combining means for indicating when said combined signal output is at a substantially zero level; and

depth indication means coupled to said signal combining means and responsive to adjustment of said adjustment means and the distance apart of said receptor for indicating the distance to a concealed conductive object.

2. A locator as set forth in claim 1 wherein said signal combining means comprises a potentiometer.

3. A locator as set forth in claim 1 further comprising an amplifier coupling the output of each receptor to said signal combining means.

4. A locator as set forth in claim 2 wherein the output of one of said receptors is connected across the full range of said potentiometer and the output of the other said receptor is connected across an adjustable portion of the range of said potentiometer.

5. A locator as set forth in claim 2 wherein the outputs of said receptors are connected in series across the full impedence Of said potentiometer and the output of said signal combining means is coupled from the adjustable arm of said potentiometer and a common receptor connection to said detection means.

6. A locator as set forth in claim 2 wherein said potentiometer is adjustable to provide a resistance which varies as the square of the distance of adjustment of said potentiometer, whereby said depth indication means comprises a linear scale.

7. A locator as set forth in claim 2 wherein said detection means comprises means for providing a variable frequency output as a function of the detected signal level.

8. A locator as set forth in claim 2 wherein said detection means includes means for providing an audible signal output indicative of the output of said signal level adjustment means.

9. A locator as set forth in claim 1 further comprising selection means coupled to at least one of said signal receptors for coupling it directly to said detection means whereby in this mode of connection said locator is adapted to determine the direction along which said object extends.

10. A locator as set forth in claim 2 wherein each said signal receptor comprises an electrical capacitor connected in parallel whereby said receptor is tuned to a preselected frequency.