The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Nov. 20, 2012

Filed:

Sep. 21, 2011
Applicant:

Stephen Mcadam, Warrington, GB;

Inventor:

Stephen McAdam, Warrington, GB;

Assignee:
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G08B 29/00 (2006.01); G08B 21/00 (2006.01); G08B 13/08 (2006.01); G08B 13/24 (2006.01); G08B 13/14 (2006.01); G01N 27/72 (2006.01); G01N 27/82 (2006.01); G01R 33/12 (2006.01);
U.S. Cl.
CPC ...
Abstract

A method for monitoring the operation of a metal detection system that comprises a balanced coil system with a transmitter coil that is connected to a transmitter unit, which provides transmitter signals having a fixed or variable transmitter frequency, and with a first and a second receiver coil that provide output signals to a receiver unit. A system adapted to operate according to an exemplary method is also provided. According to one embodiment, a carrier signal having the transmitter frequency and a monitoring signal having a monitoring frequency are provided to a modulation unit that suppresses the carrier signal and provides a modulated monitoring signal, which is supplied to a monitoring coil that is inductively coupled with at least one of the receiver coils, whose output signals are demodulated in a demodulation unit that provides a demodulated monitoring signal, which is compared in phase and/or in amplitude with a reference.


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