ask modulation and demodulation

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vishalsratti

Joined: 08 May 2009
Posts: 4

15 May 2009 1:49 ask modulation

Can anyone help me with modulation and demodulation of BASK with addition of noise and checking of error due to noise........

Please help me ASAP.... next 2 days......

Thanks Alot

vegaluisjose

Joined: 01 May 2009
Posts: 12
Location: Venezuela

15 May 2009 3:37 modulation and demodulation

BASK??? or ASK???

you need a Math software specified?

Matlab, Octave, it++, or..?

vishalsratti

Joined: 08 May 2009
Posts: 4

15 May 2009 5:20 ask demodulation

4 BASK and in matlab... its d modulation and demodulation

A binary signal m(t) should be transmitted over a channel and received in its
original form. For this to work the signal is mixed with a cosine function with specific carrier
frequency and then transmitted. The channel is noisy resulting in noise added to the modulated
signal. To recover the original signal back at the receiver, the combined signal is demodulated
by mixing it with the same cosine function and then filtering the sidebands.

hamdard

Joined: 09 Jun 2006
Posts: 215
Helped: 10

15 May 2009 8:21 ask modulation and demodulation

If you need BPSK and its simulation. I may help.

vishalsratti

Joined: 08 May 2009
Posts: 4

15 May 2009 9:09 ask modulation demodulation

Thx alot pal... but i need it on BASK... n dat in very next 2 dayz... can u help me...

as it is a finalz project 4 me... in signal n system....

Aya2002

Joined: 12 Dec 2006
Posts: 1409
Helped: 254
Location: Iraq

15 May 2009 23:22 modulation demodulation

see this general PSK type . you can modify it to ASK , it is very simple

clc;
clear all;
disp('M-Array PSK Modulation')
%create a random digital message
M=input ('M= '); %alphabet size
x=randint(input('Number of binary bit stream = '),1,M);
%%
nsample=40; %oversampling rate.
%%

%%
%use M-PSK modulation to produce y
y=modulate(modem.pskmod(M),x);
%%
%follow with rectangular pulse shaping.
ypulse=rectpulse(y,nsample);
stem(y(1:10),'filled'),grid;
%%
%%transmit signal through an AWGN Channel
ynoisy=awgn(ypulse,input('SNR in dB = '),'measured');
%%
%Create scattet plot from noisy data
scatterplot(ynoisy),grid;
%%
%Downsample at the reciever.
ydownsample=intdump(ynoisy,nsample);
%%
%Demodulate ynoisy to recover the message.
z=demodulate(modem.pskdemod(M),ydownsample);
figure;
subplot(2,1,1);
stem(x(1:10),'filled'),grid;
subplot(2,1,2);
stem(z(1:10),'filled'),grid;
%%
%Check symbole erroe rate.
[num ty]=symerr(x,z)
%%

enjoy
---------------------------------------------------------------------------------------
http://tech.groups.yahoo.com/group/ofdmandmatlab/
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Added after 2 minutes:

also see this file from matlab help "communication toolbox" it is very very very good and simple.

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fakhrisaja

Joined: 30 Oct 2009
Posts: 1
Location: indonesia

30 Oct 2009 17:39 ask modulation and demodulation

hallo..
i'm newbie..
i need help..
anyone can help me about ASK modulation?
anyone can give example bout it?
thx before

Aya2002

Joined: 12 Dec 2006
Posts: 1409
Helped: 254
Location: Iraq

30 Oct 2009 19:30 Re: ask modulation and demodulation

here the program os ASK modulation. It is very similar to the above program of the PSK modulation but just the psk replaced by ask.

clc;
clear all;
disp('M-Array ASK Modulation')
%create a random digital message
M=input ('M= '); %alphabet size
x=randint(input('Number of binary bit stream = '),1,M);
%%
nsample=40; %oversampling rate.
%%

%%
%use M-ASK modulation to produce y
y=modulate(modem.askmod(M),x);
%%
%follow with rectangular pulse shaping.
ypulse=rectpulse(y,nsample);
stem(y(1:10),'filled'),grid;
%%
%%transmit signal through an AWGN Channel
ynoisy=awgn(ypulse,input('SNR in dB = '),'measured');
%%
%Create scattet plot from noisy data
scatterplot(ynoisy),grid;
%%
%Downsample at the reciever.
ydownsample=intdump(ynoisy,nsample);
%%
%Demodulate ynoisy to recover the message.
z=demodulate(modem.askdemod(M),ydownsample);
figure;
subplot(2,1,1);
stem(x(1:10),'filled'),grid;
subplot(2,1,2);
stem(z(1:10),'filled'),grid;
%%
%Check symbole erroe rate.
[num ty]=symerr(x,z)
%%

enjoy

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saeddawoud

Joined: 27 Apr 2007
Posts: 156
Helped: 3

06 Nov 2009 16:02 Re: modulation demodulation

Aya2002 wrote:

...
nsample=40; %oversampling rate....

Is shaping is necessary after modulation, i.e.: does this affect the final result? What do you mean by oversampling, and how can we know the number that will be oversampling rate?

Regards