about the signal bandwidth...

[shaunlu]

hi guys,
I want to simulate the difference of signal bandwidth with different pulse shapping.
I use two kinds of pulse shaping: 1) rect shaping 2) half-sine shaping.
I whish to find out half-sine shaping gets good bantwidth efficiency....
I have created specturm diagram, but I dont know how to find out the bandwidth..(3dB bandwidth, 99% bandwidth... whatever.)

as follow is my code.
Thanks for your help...

*********************************
clc;
clear;
close all;

Chiprate=2*100; % Chiprate=1/Tc
Samplerate=50; %Samplerate=1 hz
cnt = (Samplerate/4:SamplerateChiprate));
HalfSineShaping= sin(pi*cnt/(Chiprate));
Message=randint(1,100)*2-1;
SineShaped = reshape((Message'*HalfSineShaping)',1,length(Message)*length(HalfSineShaping));
RectShaping=ones(1,Chiprate/Samplerate);
RectShaped = reshape((Message'*RectShaping)',1,length(Message)*length(RectShaping));

figure;
stem(HalfSineShaping)
figure;
stem(RectShaping)

figure;
stem(SineShaped)
figure;
stem(RectShaped)

SineFFT=fft(SineShaped);
SineFFTLength = 1:length(SineFFT);
RectFFT=fft(RectShaped);
RectFFTLength = 1:length(RectFFT);

figure;
plot(SineFFTLength,SineFFT)
title('Frequency content of half-sine shaping signal')
xlabel('frequency (Hz)')
grid on;

figure;
plot(RectFFTLength,RectFFT)
title('Frequency content of rect shaping signal')
xlabel('frequency (Hz)')

 

[joshuashi]

Pls take a look at the matlab function pwelch() and spectrum().

joshuashi