envelopedetector.txt

Title : Implementation of quadrature modulation and demodulation Design Object : By implementing qu

clear all
clc
cla

load('c:\DSD_hom2\input.mat');
load('c:\DSD_hom2\lpf_coe.mat');

n=linspace(0,935,936);
f=linspace(-350000,350000,936);


figure(1); subplot(1,2,1);
plot(n,RFdata);
title('Input RF data - time'),xlabel('Index'), ylabel('amplitude');


figure(1); subplot(1,2,2);
plot(f, 20*log(fftshift(abs(fft(RFdata)))/323.9459)); % normalize窍扁 困秦 林颇荐 己盒狼 弥措蔼栏肺 唱传 第 dB scale肺 
title('Input RF data - frequency'),xlabel('Index'), ylabel('amplitude');


figure(2); subplot(1,2,1);
plot(n, Envelope);
title('Input Envelope - time'),xlabel('Index'), ylabel('amplitude');


figure(2); subplot(1,2,2);
plot(f, 20*log(fftshift(abs(fft(Envelope)))/655.2291));
title('Input Envelope - frequency'),xlabel('Index'), ylabel('amplitude');


fs= 40*10^6;
ts=1/fs;
n1=[0:ts:0.00002339];


figure(3); subplot(1,2,1);
RFsquare= RFdata.*RFdata;
plot(n1, RFsquare);


figure(3); subplot(1,2,2);
plot(f, 20*log(fftshift(abs(fft(RFsquare)))/1.5126e+003));


z1 = convn(RFsquare, h1, 'same');


figure(4); subplot(1,2,1);
plot(n1,z1);


figure(4); subplot(1,2,2);
plot(f, 20*log(fftshift(abs(fft(z1)))/1.6213e+003));

%% square root%%
z1_sqrt=sqrt(z1);


figure(5); subplot(1,2,1);
plot(n1,z1_sqrt);


figure(5); subplot(1,2,2);
plot(f, 20*log10(fftshift(abs(fft(z1_sqrt)))/485.5087));

figure(6); subplot(1,2,1);
plot(n1, abs(RFdata));


figure(6); subplot(1,2,2);
plot(f, 20*log(fftshift(abs(fft(abs(RFdata))))/416.8674));


z2 = convn(abs(RFdata), h2, 'same');


figure(7); subplot(1,2,1);
plot(n1, z2);

fft_z2 = fftshift(abs(fft((z2))));

figure(7); subplot(1,2,2);
plot(f, 20*log10(fft_z2/450.3224+0.000000000001));
xlabel('frequency');
ylabel('y2(dB)');