Wednesday, 6 March 2013

A rectification of the programme

In the original programme, we used the former 57000 data points to plot the Q-U Lissajous figure of one period. We chose 57000 before, because the Lissajous shown as below was a closed shape, which looked like the graph for one period.
 
But this method is unwarranted, we should choose the amount of the data points for one period by calculating based on the frequency we got. The frequency is 40kHz. Thus, the period is 2.5*10^-5s. The interval of the data points is 5*10^-10s. Therefore, the former 50000 points should be used, as  (2.5*10^-5)/ (5*10^-10)=50000. The correct Q-U Lissajous is shown below.
 
After we rectified the programme, the work done of one period is 0.0015189J and the discharge power is 60.756W. This result is closer to the theoretical value 60W than before. The content on the poster was modified and then printed.
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1 comment:

  1. Ty Ric2 November 2013 at 16:07

    Hi. I really appreciate your write up.
    My question is why did you use fft to obtain the frequency instead of using the values of those peak voltage to obtain the frequency. though it might be an approximate value that you will get?
    and secondly while smoothing the Lissajous plot how did you define the span of the smooth command?
    Thank you

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