bao cao lab1 dsp thang 08dt3

8/13/2019 Bao Cao Lab1 DSP Thang 08DT3

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I HC NNG

TRNG I HC BCH KHOA

KHOA IN T- VIN THNG

---- ----

BO CO LAB1:

Introduction toMATLAB and

Scripts

Gio vin hng dn: Nguyn Hi Triu Anh

Sinh vin thc hin: Phan Quc Thng

Lp : 08DT3

Nhm: 14B


2/15

1. Ma trn: To ma trn x:

Truy cp gi trca ma trn x:

To ma trn z tma trn y:

Cc php ton tma trn:

>> x=[3 1 5; 6 4 1]

x =

3 1 5

6 4 1

>> y=[1 2 3]

y =

1 2 3

>> z=[1 2 3]'

z =

1

2

3

>> x(1,2)

ans =

1

>> x=[2;4]

x =

2

4

>> y=[3;1]

y =

3

1


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2. Plot and Subplot: title('Here is a title'); - Adds the text "Here is a title" to the top of the plot. xlabel('Control Voltage (mV)'); - Adds text to the X-axis. ylabel('Current (mA)'); - Adds text to the Y-axis. grid on; - Adds a grid to the plot.

Vth theo 3 trc x, y, z

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.5

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.5

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.5

1

>> x*y'

ans =

6 2

12 4

>> x'*y

ans =

10

>> x.*y

ans =

6

4

>> subplot(3,1,1);

>> subplot(3,1,2);

>> subplot(3,1,3);


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Create and plot a signal x0 (t) = te^(-t)

Lnh matlab:

ththu c:

-10 -8 -6 -4 -2 0 2 4 6 8 10-0.4-0.3-0.2-0.1

00.10.20.30.4

>> t = -10:0.1:10;

xo = t .* exp(-abs(t));

plot(t, xo);

grid;


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create the signals: xe (t) = !t!*e^(-!t!)x (t) = 0:5 _ [x0 (t) + xe (t)]

Plot all signals together using 3 plots stacked on top of each other with the subplotcommand:Lnh matlab:

thvc tmatlab:

-10 -8 -6 -4 -2 0 2 4 6 8 10-0.5

0

0.5

-10 -8 -6 -4 -2 0 2 4 6 8 100

0.2

0.4

-10 -8 -6 -4 -2 0 2 4 6 8 100

0.2

0.4

>> t = -10:0.1:10;

xo = t .* exp(-abs(t));

xe=abs(t).*exp(-abs(t));

x = 0.5 * [xo + xe];

subplot(3,1,1);

plot(t,xo);

subplot(3,1,2);

plot(t,xe);


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3.Complex Numbers:Lnh matlab:

MATLAB uses the letter i instead of j by default. Electrical Engineers prefer using jhowever,

and MATLAB will recognize that as well. Try entering i+j, does this make sense.

De_ne z1 = 1 + j . Find the magnitude, phase, real and imaginary parts of z (using abs(),angle(), real(), imag(), respectively).

>> sqrt(-1)

ans =

0 + 1.0000i

>> abs(z1)

ans =

1.4142

>> real(z1)

ans =

1

>> imag(z1)

ans =

1


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Find the magnitude of z1 + z2 where z2 = 2e^(j*pi/3)

Compute the value of j^j:

4.Complex Functions:Create a signal x1 (t) = te*(jt):

Lnh matlab:

>> z1=1+j

z1 =

1.0000 + 1.0000i

>> z2=2*exp(j*pi/3)

z2 =

1.0000 + 1.7321i

>> z=z1+z2

z =

2.0000 + 2.7321i

>> j^j

ans =

0.2079

>> t = -10:0.1:10;

>> x1=t.*exp(j*t);

>> plot(t, x1); grid;


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5.Playing and Plotting a Sound:Lnh matlab:

-10 -8 -6 -4 -2 0 2 4 6 8 10

-10

-8

-6

-4

-2

0

2

4

6

8

10

0 1 2 3 4 5 6 7 8 9-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

>> load handel;

plot(linspace(0,9,7311

3),y);

sound(y);


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6. Script Files:a. Exercise 1:

Now we are going to edit the dampedCosine.m file to create our own script file. At

the top of the file, you will see the following commands

diary 'your_name_Lab1.txt'

disp('NAME: your name')

disp('SECTION:your section')

1.Edit the dampedCosine.m (download from link above) script and enter your name and

section where indicated. Save this new version of the script as yourName_dampedCosine.m

2. Edit the script to create a second signal where the cosine with twice the period

(which gives half the frequency) of the first.


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3. Add to the script the commands to plot these together with the first signal on top and the

second on the bottom. In other words, you should have a single figure with two different plots,

one on top and one on bottom. You will need to use subplot and plot. Save this plot as

yourName_dampedCosine.fig


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.

4. Show the TA your dampedCosine plot. What is the period of the cosine?

- y1(x) signal have the period of the cosine is :T1 =

=1 (s)

- y2(x) signal have the period of the cosine isT2=

=2 (s)

b.Exercise 2:

Download and run compexp.m2 , which includes a 3-D plot of a complex exponential, y

(t) , as well as 2-D magnitude/phase and real/imaginary plots. You need 2 2-D plots to have the

same information as the 3-D plot

ddng kho st sthay i ca tn hiu,ta sdng thm 2 lnh:

a=input('push a:');

f=input('push f:');

-5 -4 -3 -2 -1 0 1 2 3 4 5-1

-0.5

0

0.5

1

time

amplitude

f(x)=exp(-abs(x))cos(2*pi*x)

-5 -4 -3 -2 -1 0 1 2 3 4 5-0.5

0

0.5

1

time

amplitude

f(x)=exp(-abs(x))cos(pi*x)


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vi f v a l cc gi trnhp tbn phm

Ta c hm nh sau:

Khi chy chng trnh,trn ca scommand sxut hin:

push a:

push f:

ta sln lt nhp cc gi trca f v a vo.


13/15

1/ How would you change the script to make the oscillation frequency lower by half?

tn sgim i mt na,ta ginguyn gi trca a=1,v ln lt thay i gi trca f l f=1v f=0.5.Ta c hnh vnh sau:

Khi a=1,f=1 Khi a=1,f=0.5

2/ How would you change the script to make the decay faster?

gim bin ca tn hiu,ta ginguyn gi trf=1,v ln lt thay i gi trca a l a=1 va=2.Ta c hnh vnh sau


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Khi a=1,f=1 Khi a=2,f=1

Tn hiu y(t) c phn tch nh sau:

y(t)=()

=3 *

=3 *(cos(-2 jsin(-2)

=3 *(cos() +jsin( ))

Chnh v vy,khi ta thay i a th slm cho bin ca tn hiu thay i,v khi thay i f chnhl thay i tn sca tn hiu(hay thay i chu k ca tn hiu)


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bao cao lab1 dsp thang 08dt3

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