Chris' Page for HW 13 (Sampling at 3Hz): Difference between revisions
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(New page: '''Sample <math> sin( 2 \pi nt) </math> at 3Hz; take the DFT, explain the results.''') |
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'''Sample <math> sin( 2 \pi nt) </math> at 3Hz; take the DFT, explain the results.''' |
'''Sample <math> sin( 2 \pi nt) </math> at 3Hz; take the DFT, explain the results.''' |
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<pre> |
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t1 = 0:1/3:3; |
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t2 = 0:1/1000:3; |
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y1 = sin(2*pi*t1); |
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y2 = sin(2*pi*t2); |
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NFFT1 = 2^nextpow2(length(y1)); |
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NFFT2 = 2^nextpow2(length(y2)); |
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Y1 = fft(y1,NFFT1)/length(y1); |
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Y2 = fft(y2,NFFT2)/length(y2); |
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f1 = 1/3./(2*linspace(0,1,NFFT1/2)); |
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f2 = 10000./(2*linspace(0,1,NFFT2/2)); |
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figure(2) |
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hold on |
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h = stem(t1(1:10),y1(1:10),'fill','--'); |
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set(get(h,'BaseLine'),'LineStyle',':') |
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set(h,'MarkerFaceColor','green') |
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plot(t1(1:10),y1(1:10), t2(1:3000), y2(1:3000)) |
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legend('3Hz Sample Points','Sine sampled at 3Hz','Sine sampled at 1kHz') |
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xlabel('Time in seconds') |
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ylabel('Magnitude') |
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title('Sin(2\pi t) Sampled at 3 Hz') |
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hold off |
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</pre> |
Revision as of 15:30, 14 December 2007
Sample at 3Hz; take the DFT, explain the results.
t1 = 0:1/3:3; t2 = 0:1/1000:3; y1 = sin(2*pi*t1); y2 = sin(2*pi*t2); NFFT1 = 2^nextpow2(length(y1)); NFFT2 = 2^nextpow2(length(y2)); Y1 = fft(y1,NFFT1)/length(y1); Y2 = fft(y2,NFFT2)/length(y2); f1 = 1/3./(2*linspace(0,1,NFFT1/2)); f2 = 10000./(2*linspace(0,1,NFFT2/2)); figure(2) hold on h = stem(t1(1:10),y1(1:10),'fill','--'); set(get(h,'BaseLine'),'LineStyle',':') set(h,'MarkerFaceColor','green') plot(t1(1:10),y1(1:10), t2(1:3000), y2(1:3000)) legend('3Hz Sample Points','Sine sampled at 3Hz','Sine sampled at 1kHz') xlabel('Time in seconds') ylabel('Magnitude') title('Sin(2\pi t) Sampled at 3 Hz') hold off