Automatic Threshold Detection for Tachometer Signals
First Claim
1. A method for determining peak amplitude values in a tachometer signal in order to calculate a threshold value for the tachometer signal and for determining associated statistical outlier values, the method comprising:
- (a) sensing the tachometer signal;
(b) determining a set of peak amplitude values in the tachometer signal over a period of time and defining P0 as the number of peak amplitude values;
(c) calculating a mean amplitude value μ and
a standard deviation amplitude value σ
of the peak amplitude values in the set;
(d) if
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Abstract
A method is described for automatically determining a proper threshold for a tachometer signal in order to produce desired tachometer pulses necessary for analysis of machine vibration data. A tachometer signal is low-pass filtered to exclude high frequency noise and a running derivative of the filtered tachometer waveform is taken to create a derivative waveform. Another waveform is created that includes only positive values from the derivative waveform that correspond to positive values in the low-pass filtered tachometer waveform. In general, a tachometer signal has the greatest derivative value (slope) when a tachometer pulse is present. Based on this observation, a threshold value is determined using both the low-pass filtered tachometer waveform and the positive-value derivative waveform along with statistics from both waveforms.
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Citations
11 Claims
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1. A method for determining peak amplitude values in a tachometer signal in order to calculate a threshold value for the tachometer signal and for determining associated statistical outlier values, the method comprising:
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(a) sensing the tachometer signal; (b) determining a set of peak amplitude values in the tachometer signal over a period of time and defining P0 as the number of peak amplitude values; (c) calculating a mean amplitude value μ and
a standard deviation amplitude value σ
of the peak amplitude values in the set;(d) if - View Dependent Claims (2)
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3. A method for determining a plurality statistically significant amplitude values of a signal and excluding statistical outlier values prior to further processing of the signal, the method comprising:
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(a) determining a set of peak amplitude values in the signal and defining P0 as the number of peak amplitude values; (b) calculating a mean amplitude value μ and
a standard deviation amplitude value σ
of the peak amplitude values in the set;(c) if - View Dependent Claims (4, 5, 6, 7, 8)
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9. A method for determining a plurality statistically significant amplitude values of a signal and excluding statistical outlier values prior to further processing of the signal, the method comprising:
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(a) determining a set of peak amplitude values in the signal and defining P0 as the number of peak amplitude values; (b) calculating a mean amplitude value μ and
a standard deviation amplitude value σ
of the peak amplitude values in the set;(c) if - View Dependent Claims (10, 11)
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Specification