Patent ID: 8482273
Filing Date: 2013-07-09
Classification: G01R

Abstract:
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.