US 11,906,685 B2
Distinguishing false signals in cable locating
John E. Mercer, Gig Harbor, WA (US); and Albert W. Chau, Woodinville, WA (US)
Assigned to Merlin Technology Inc., Kent, WA (US)
Filed by Merlin Technology Inc., Kent, WA (US)
Filed on Jan. 25, 2021, as Appl. No. 17/157,106.
Application 17/157,106 is a continuation of application No. 16/132,361, filed on Sep. 15, 2018, granted, now 10,901,106.
Application 16/132,361 is a continuation of application No. 15/785,986, filed on Oct. 17, 2017, granted, now 10,101,487, issued on Oct. 16, 2018.
Application 15/785,986 is a continuation of application No. 15/130,840, filed on Apr. 15, 2016, granted, now 9,804,287, issued on Oct. 31, 2017.
Application 15/130,840 is a continuation of application No. 14/231,603, filed on Mar. 31, 2014, granted, now 9,335,431, issued on May 10, 2016.
Application 14/231,603 is a continuation of application No. 13/301,487, filed on Nov. 21, 2011, granted, now 8,698,501, issued on Apr. 15, 2014.
Application 13/301,487 is a continuation of application No. 12/979,793, filed on Dec. 28, 2010, granted, now 8,080,998, issued on Dec. 20, 2011.
Application 12/979,793 is a continuation of application No. 12/512,853, filed on Jul. 30, 2009, granted, now 7,884,610, issued on Feb. 8, 2011.
Application 12/512,853 is a continuation of application No. 12/137,424, filed on Jun. 11, 2008, granted, now 7,586,308, issued on Sep. 8, 2009.
Application 12/137,424 is a continuation of application No. 11/557,432, filed on Nov. 7, 2006, granted, now 7,397,249, issued on Jul. 8, 2008.
Application 11/557,432 is a continuation of application No. 11/105,804, filed on Apr. 13, 2005, granted, now 7,151,375, issued on Dec. 19, 2006.
Prior Publication US 2021/0247539 A1, Aug. 12, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. G01V 3/08 (2006.01); G01V 3/12 (2006.01); G01V 3/17 (2006.01); G01V 3/165 (2006.01)
CPC G01V 3/08 (2013.01) [G01V 3/12 (2013.01); G01V 3/165 (2013.01); G01V 3/17 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A transmitter 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, said transmitter comprising:
a frequency generator configured to generate said locating signal frequency and to generate a reference signal, with said locating signal frequency impressed thereon;
a telemetry transmitter configured to transmit the reference signal as an electromagnetic reference signal; and
a coupler configured to couple the locating signal frequency onto the first cable such that detection of a phase shift between the locating signal and the false locating signal at a receiving location and based on the reference signal distinguishes the locating signal from the false locating signal.