Methods of detecting anomalies in ambient alternating current fields

• US 7,920,975 B2
• Filed: 08/20/2007
• Issued: 04/05/2011
• Est. Priority Date: 08/18/2006
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Hull, David M., Vinci, Stephen J.
• Primary Examiner(s): TSAI, CAROL S W
• Application Number:
  US11/892,152
• Publication Number:
  US 20080255779A1
• Time in Patent Office: 1,324 Days
• Field of Search: 702/57, 702/58, 702/65, 324/209, 324/228, 324/233, 324/239, 324/240, 324/207.17, 324326-329, 324/117.R, 324/249, 324/207.18, 701 45- 48, 701/1, 701/36, 738/626.9, 361/42, 361/45, 361/93.1, 361/78
• US Class Current: 702/57
• CPC Class Codes: G01R 29/12 Measuring electrostatic fields or voltage-potential

Abstract

Methods of detecting anomalies in ambient alternating current (AC) fields are provided. An exemplary embodiment of such a method includes the steps of placing an AC field sensor in an ambient AC field, generating a signal representative of the ambient AC field received by the sensor, and processing the signal to determine if the ambient AC field includes any anomalies. Various applications for the methods are also provided.

Claims

1. A method of detecting anomalies in an ambient alternating current (AC) electric field generated by an AC power line, comprising the steps of:

placing an AC electric field sensor in an ambient AC electric field generated by an AC power line;

generating a signal representative of the ambient AC electric field received by the AC electric field sensor; and

processing the signal to determine if any anomalies are present in the ambient AC electric field,

said step of processing the signal includes the step of demodulating the signal with a synchronous demodulation circuit to generate a demodulated signal that includes portions representative of anomalies in the ambient AC electric field,

wherein said synchronous demodulation circuit includes a mixer connected to a low pass filter and a high-gain amplifier connected to the mixer;

the signal is fed to the mixer and the high-gain amplifier; and

the demodulated signal is output by the low pass filter.

2. The method of claim 1, wherein the ambient AC electric field is generated by the AC power line when the AC power line is energized but regardless of whether or not the AC power line is supplying current to a load.

3. The method of claim 1, wherein the signal is an amplitude modulated signal.

4. The method of claim 1, wherein the step of processing the signal includes the step of demodulating the signal with an amplitude demodulation circuit to generate a demodulated signal that includes portions representative of anomalies in the ambient AC electric field.

5. The method of claim 4, wherein:

the amplitude demodulation circuit includes an envelope detector connected to a low pass filter;

the signal is fed into the envelope detector; and

the demodulated signal is output by the low pass filter.