MSR145 Analog Testing
Table of Contents

MSR145 Analog Testing
Raw Data Collected
The tests were run and data collected by each DAQ device. The data and results can be found here. The data sets from each test were plotted against each other and the sine wave input to both systems. Plots were created by linearly interpolating each datapoint.
Test 1


Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

 Note: The data used to create these graphs have been phase shifted by approximation. Therefore, any outofphase difference between the plots should be ignored.
The first test, results provided to the left, shows that at a lower frequency of about 1Hz, both DAQs perform well. A very clear sine wave can be seen for both systems. The MSR145 and NI system show similar results, which accurately approximate the input wave.
The second test uses an approximate input of 5Hz. The test results in a less defined sine wave than the first test. However, these data plots are still a good approximation of the input wave. More importantly, the NI DAQ and MSR145 yielded similar results.
The third test, using an approximate input of 15.5Hz, shows the point in which the sampling rate creates a noticeable difference in data accuracy. The NI system was collecting data at 100S/s, while the MSR145 was still using the 51.2S/s sample rate. While there is a difference in the plots, both data plots still give accurate enough data to approximate the input wave. This is because the input is still under the Nyquist limit of ½ the sample rate.
Test 4 was the result of a 25Hz input wave into the MSR145. This test emphasized the fact that the MSR145 has a sample rate of 51.2S/s, not 50S/s. This slight difference in frequency creates the phenomenon known as beats, which can be clearly seen in the plot for Test 4. Beats are caused by when two sinusoidal waves of close but not exact frequencies interfere with each other. This is exactly the case in this situation. With an input of 50 Hz and a measurement rate of 51.2S/s, the measured points are not in synch with the input. Each point is picking up a sequentially higher value, since the input and measurement waves are slightly offset.
FFT Analysis
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