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SUS Source Level Error Analysis
UNDERWATER SYSTEMS INC ROCKVILLE MD
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The report provides an analysis of major terms which contribute to signal analysis error in a proposed experiment to calibrate source levels of SUS Signal Underwater Sound. A unique model of the digital signal analysis process was used to verify and empirically extend the results of analytic studies. The analytic findings indicate that the discrete Fourier transform, without windowing, is error free when the signal is adequately anti-alias filtered, and wholly contained in the analysis time window. The model was used to generate exact spectra for comparison with digitally analyzed spectra. Errors due to FFT roundoff, aliasing, quantization and registration were studied to verify error expressions and to identify empirical error bounds. Discrete amplitude representation quantization was found to introduce systematic error at low frequencies, for the particular time series that were studied, when insufficient resolution was provided.
APPROVED FOR PUBLIC RELEASE