Method for Locating an Underground Septic Tank, Conduit, or the Like Using Injection/Detection Synchronization of an Acoustic Signal and Digital Signal Processing

• US 20090112476A1
• Filed: 11/23/2008
• Published: 04/30/2009
• Est. Priority Date: 11/23/2008
• Status: Active Grant

• Current Assignee: David H. Parker
• Original Assignee: David H. Parker
• Inventors: Parker, David H.
• Granted Patent: US 8,116,994 B2
• Time in Patent Office: Days
• US Class Current: 702/6
• CPC Class Codes: G01V 1/001 Acoustic presence detection

Abstract

This invention relates to a non-invasive method for easily locating an underground septic tank, distribution box, field line, conduit, or the like. In the preferred embodiment, prescribed acoustic signals are injected into an underground cavity via an accessable port and remotely detected by a time synchronized detector in contact with the ground which cross correlates the detected signal with a duplicate of the prescribed acoustic signal in order to reject background noise, and thus locate the underground cavity. A frequency sweep is conducted to exploit cavity resonance modes and thus further enhance the signal to noise ratio.

Claims

1. A method comprising the steps of:

(a) generating a prescribed acoustic wave wherein the frequency f of said acoustic wave matches at least one resonant mode of an underground cavity for at least a time equal to 2/f

(b) acoustically coupling said acoustic wave to said underground cavity

(c) establishing a first time reference, wherein said first time reference governs the generation of said acoustic wave

(d) electronically detecting said acoustic wave, at a remote location in acoustic communication with said underground cavity through an earth path to produce a measurement

(e) establishing a second time reference, wherein said second time reference is synchronized with said first time reference, and said second time reference governs said measurement

(f) digitizing and storing a sequential series of said measurements

(g) performing digital processing on said series of measurements, wherein said digital processing comprises cross correlating said series of measurements with a priori amplitude values of said prescribed acoustic wave to produce a result related to the intensity of said acoustic wave at said remote location

(h) communicating said result to an operator

2. a method comprising the steps of:

(a) generating a prescribed acoustic wave wherein the frequency f of said acoustic wave matches at least one resonant mode of an underground cavity for at least a time equal to 2/f

(b) acoustically coupling said acoustic wave to said underground cavity

(c) detecting said acoustic wave, at a remote location in acoustic communication with said underground cavity through an earth path wherein said detecting is performed by human or animal sense