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Apparatus and method for monitoring and controlling detection of stray voltage anomalies

  • US 8,482,273 B2
  • Filed: 09/14/2012
  • Issued: 07/09/2013
  • Est. Priority Date: 12/23/2004
  • Status: Active Grant
First Claim
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1. An apparatus for detecting an electrical field comprising:

  • a sensor probe that generates one or more signals corresponding to an electrical field detected by at least one electrode coupled to the sensor probe;

    a processor, coupled to the sensor probe, that digitizes the one or more signals into samples and that performs a Fast Fourier Transform (FFT) on a most recent set of samples for every 16 samples digitized, and then performs a second FFT at a rate of 60 Hz to produce field strength values related to each of electrodes to generate a smoothed frequency domain representation with a domain overlap of the one or more signals at a predetermined rate, and that analyzes the frequency domain representation to identify a voltage anomaly in the electric field;

    a prescaler that prescales field strengths to exclude electrical fields that produce an inaudible audio indication;

    an audio generation device, coupled to the processor, that outputs a variable audio indication proportional to strength of the detected electrical field using a pitch table storing discrete pitch values with entries corresponding audio indication tones to electrical field strength, wherein each entry is no more than one-eighth of a step change in pitch from a next discrete pitch and wherein the audio generation device has a discretely variable alarm threshold, and the audio indication is based on an average of signals from the sensor probes and the variable audio indication is a discrete tone;

    a timer register, coupled to the audio generation device, that counts down to zero, and when the timer register reaches zero, that reloads the count from a period register for avoiding generation of transient pitch discontinuities by updating the count during high-to-low or low-to-high transitions of the variable audio indication.

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