### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 2pSP11. Frequency normalized leakage correction technique.

**Casey R. Winkel
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Kenton A. Shipley
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P. G. Vaidya
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Tim A. Doughty
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*Dept. of Mech. and Mater. Eng., Washington State Univ., Pullman, WA 99164
*

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Leakage is a problem in nearly all aspects of signal processing,
especially when the FFT is involved. Leakage takes the form of wide frequency
spikes due to a ``spilling over'' of information across frequency bins and
occurs most often when the sampling frequency is not an integer multiple of the
base frequency. The leakage correction method presented here substantially
reduces this problem. The method resamples the original time domain data within
specified limits. A frequency error measurement is taken for each sampling rate
within the defined limits. The minimum frequency error is recorded along with
the fundamental frequency of the record. This method resamples the entire
signal one record at a time with a linear interpolator. Nyquist criteria must
be satisfied at all times to validate the use of the linear interpolation.
Nyquist criteria is satisfied if the sampling rate is at least twice as large
as the highest frequency in the signal. The resampled data must satisfy three
conditions to eliminate leakage. (1) 2[sup n] points per period. (2) Integer
number of periods per record. (3) Satisfy Nyquist criteria. The method here
satisfies these conditions and results in enhanced time domain data. [sup
a)]Now at Martin Marietta, Knolls Atomic Power Labs, Schenectady, NY. [sup
b)]Now at Dept. of Mech. Eng., Purdue Univ., West Lafayette, IN.

All posters will be on display from 1:15 to 4:15 p.m. To allow
contributors an opportunity to see other posters, contributors of odd-numbered
papers will be at their posters from 1:15 to 2:45 p.m. and contributors of
even-numbered papers will be at their posters from 2:45 to 4:15 p.m.