AE/ME 201 – Spring 2005 Data Acquisition and Digital Signal Processing

This experiment is intended to introduce the stu-dent to data acquisition systems and a few data analysis techniques. In this experiment the student will construct a LabVIEW Virtual Instrument (VI) that instructs a digital computer equipped with an analog to digital converter, ADC or A/D, to sam-ple and record a signal. A matlab script will then be constructed to fit a curve to a phase plot and a Fourier transform of the time series data. Background: In this lab, you will be introduced to data acquisi-tion, digital signal processing, and Fourier analysis. There are three main sources of error encountered when digitizing signals; clipping, quantization, and aliasing. You will be asked to construct a LabVIEW Virtual Instrument (VI) and use it to sample an analog signal. The VI will acquire a block of data and then record the time series data to a file. This exercise will provide you with an introduction to LabVIEW programming. After the data has been recorded you will be asked to construct a Matlab script to load and process the data. General Considerations for ADC[1,2] Analog to digital conversion, ADC, produces a se-ries of numbers each of which corresponds to the weighted intergral of the analog signal over some time period, ∆s, called the aperture which is less than or equal to the sampling period, ∆q. Therefore, if u(t) is the signal to be sampled, an equation for the digital sample, un, can be written as: un = 1 ∆s ∫ tn tn−∆s u(t)dt+ µ (1) where µ is the quantization noise