Application of Acoustical Holography to Noise Data Analysis
A measure basic to nearly all noise data analysis works is filtering. Filtering is the extraction of useful information from data. Holography is information and so it can be used to extract certain information contained in a signal. Here we are interested to extract the repetitive or periodic signals from noise. The technique used is acoustical correlation filtering. We first record the periodic signal with a reference signal and this acoustical hologram is the complex filter function. The experimental method of recording the hologram follows that of Graham’s thesis. The filtered signal is the convolution of tie composite noise spectrum to be analyzed and the reconstruction from the holographic filter function. The next step is to obtain the reconstruction of the filter function in digital form. Digitization is done from the photographic form of the hologram. The digitized form serves as an input for the computer. The filtered signal then can be given as one output of the computer.
KeywordsFree Vibration Periodic Signal Filter Function Noise Control Filter Signal
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