1 files changed, 35 insertions, 0 deletions
diff --git a/737/CH2/EX2.1/Example2_01.sce b/737/CH2/EX2.1/Example2_01.sce
new file mode 100644
index 000000000..9c849e45a
--- /dev/null
+++ b/737/CH2/EX2.1/Example2_01.sce
@@ -0,0 +1,35 @@
+//Example 2.1 page 19
+//Suppose that an analog signal is given as
+//x(t) = 5*cos(2*pi*1000t), for t >= 0
+//and is sampled at the rate of 8,000 Hz.
+//a. Sketch the spectrum for the original signal.
+//b. Sketch the spectrum for the sampled signal from 0 to 20 kHz.
+
+clc;
+clear;
+close;
+fs = 8000;//Hz
+t = 1:(1/fs):10;
+x = 5*cos(2*%pi*1000*t);
+
+//c1 and f1 are derived using the euler's identity which gives
+//  5cos(2pi*1000t) = 2.5 * %e^(%i*2*%pi*1000t)+ 2.5 * %e^(-%i*2*%pi*1000t)
+c1 = [2.5 2.5];    
+f1 = [-1 1];//kHz
+
+ax=gda();
+ax.thickness = 2;
+ax.y_location = "origin";
+ax.x_location = "origin";
+
+subplot(2,1,1)
+plot2d3(f1,c1)
+xtitle('Spectrum of the analog signal in Example 2.1(a)','f(kHz)','X(f)');
+
+//c2 = [2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5]
+//f2 = [-17 -15 -9 -7 -1 1 7 9 15 17]
+c2 = repmat([2.5],1,10);//amplitude is same for each
+f2 = [f1-16 f1-8 f1 f1+8 f1+16];//after sampling, spectrum is replicated cyclically with centered at +-n8000Hz
+subplot(2,1,2);
+plot2d3(f2,c2)
+xtitle('Spectrum of the sampled signal in Example 2.1(b)','f(kHz)','Xs(f)');
+\ No newline at end of file