【跳频通信】基于MATLAB的跳频通信系统仿真

1.软件版本

matlab2015a

2.系统程序

clc;
clear;
close all;
warning off;
addpath 'func\'
addpath 'func\mfiles\'


load data.mat
fs                  = 100e6;
Nfft                = 4096;
fc                  = 5.8e9;
% [x1,t1,ssf1,yy1]    = plotspec(x,1/fs);
% figure;
% plot(ssf1,yy1)         % plot magnitude spectrum
% xlabel('frequency'); 
% ylabel('magnitude')   % label the axes

 
frameNumber = floor(length(x)/Nfft);
txBlockFFT  = zeros(frameNumber,Nfft);
%对信号进行短时傅里叶变换，得到跳频图案
for i = 0:frameNumber-1
    start                         = i*Nfft;
    txBlockFFT(i+1,:)             = fftshift(fft(x(start+1:start+Nfft)));
    %找出跳频图案中横轴上每个时间上对应的最大峰值，从时间开始到结束写个循环就行，
    [maxValue(i+1),maxIndex(i+1)] = max(abs(txBlockFFT(i+1,:)));
end
%计算峰值均值
Level = 10*mean(maxValue);

delta_f     = fs/Nfft;
f           = delta_f: delta_f: fs;
f           = f - fs/2;

%detect vaalid signal
validIndexCount             = 1;
validIndex                  = zeros(1,1);
validIndex(validIndexCount) = 0;
validFrameCount             = 0;

figure;
for i = 1:frameNumber-1
    i
    %峰值搜索
    if(max(abs(txBlockFFT(i+1,:))> Level))
        
        validFrameCount             = validFrameCount + 1;
        validFrame(validFrameCount) = i+1;
        if(abs(maxIndex(i+1) - validIndex(validIndexCount)) > 40)
           validIndexCount             = validIndexCount +1;
           validIndex(validIndexCount) = maxIndex(i+1) ;
           detectFHFc                  = validIndex(2:end)*fs/Nfft- fs/2;
        end
        
        detectFHResult(i+1) = maxIndex(i+1)*fs/Nfft- fs/2+fc;
        t                   = (0:length(detectFHResult)-1)*Nfft/fs;
        plot(t,detectFHResult,'c*');
        hold on
    end
    axis([0,0.1983,5.74e9,5.86e9]);
    pause(0.001);
end
hold on;
y_label = fc*ones(1,length(detectFHResult));
plot(t,y_label,'r');
ylim([fc-50e6 fc+50e6]);
xlabel('时间s')
ylabel('频率Hz');
grid on;


FT = zeros(1000,length(t));
%归一化频率
indx=find(detectFHResult==0);
detectFHResult1=detectFHResult;
detectFHResult1(indx)=[];

detectFHResult2 = detectFHResult-min(detectFHResult1);
indx=find(detectFHResult2<0);
detectFHResult2(indx)=0;
detectFHResult3 = floor(1000*detectFHResult2/max(detectFHResult2));
for i = 1:length(t)
    if detectFHResult3(i)>0
       FT(detectFHResult3(i),i) = 1;
    end
end
SE   = strel('disk',24);
FT1  = imdilate(FT,SE);
SE1  = strel('disk',4);
FT1a = imerode(FT1,SE1);
SE1  = strel('disk',8);
FT2a = imerode(FT1,SE1);
SE1  = strel('disk',12);
FT3a = imerode(FT1,SE1); 
SE1  = strel('disk',16);
FT4a = imerode(FT1,SE1); 
SE1  = strel('disk',20);
FT5a = imerode(FT1,SE1); 
SE1  = strel('disk',23);
FT6a = imerode(FT1,SE1); 


 


FTf  = FT1a+FT2a+FT3a+FT4a+FT5a+FT6a;
[X,Y]=meshgrid(t,0.001:0.001:1); %横坐标为1953~2006，纵坐标1~54
 
figure;
contour(X,Y,FTf);
xlabel('time/s');
ylabel('归一化频率f/s');

clc;
clear;
close all;
warning off;
addpath 'func\'
addpath 'func\mfiles\'


load data.mat
fs                  = 100e6;
Nfft                = 4096;
fc                  = 5.8e9;
[x1,t1,ssf1,yy1,yy2]= plotspec(x,1/fs);
figure;
plot(ssf1(1:1:end)+fc,yy1(1:1:end))         % plot magnitude spectrum
xlabel('frequency(Hz)'); 
ylabel('magnitude')   % label the axes


fs          = 100e6;
Nfft        = 4096;
frameNumber = floor(length(x)/Nfft);
txBlockFFT  = zeros(frameNumber,Nfft);
for i = 0:frameNumber-1
    i
    start                   = i*Nfft;
    txBlockFFT(i+1,:)       = fftshift(fft(x(start+1:start+Nfft)));
   [maxValue maxIndex(i+1)] = max(abs(txBlockFFT(i+1,:)));
end
fc          = 5.8e9;
delta_f     = fs/Nfft;
f           = delta_f: delta_f: fs;
f           = f - fs/2;

%detect vaalid signal
validIndexCount             = 1;
validIndex                  = zeros(1,1);
validIndex(validIndexCount) = 0;
validFrameCount = 0;


for i = 1:frameNumber-1
    i
    if(max(abs(txBlockFFT(i+1,:))> 280))
        validFrameCount = validFrameCount + 1;
        validFrame(validFrameCount) = i+1;
        if(abs(maxIndex(i+1) - validIndex(validIndexCount)) > 40)
           validIndexCount             = validIndexCount +1;
           validIndex(validIndexCount) = maxIndex(i+1) ;
           detectFHFc                  = validIndex(2:end)*fs/Nfft- fs/2;
        end
        detectFHResult(i+1) = maxIndex(i+1)*fs/Nfft- fs/2+fc;
        t = (0:length(detectFHResult)-1)*Nfft/fs;
        hold on
    end
end

 
ind1 = find(abs(detectFHResult)>0) ;
ind2 = find(detectFHResult==0) ;
detectFHResult(ind2)=[];


flag = [];
for i = 1:length(ind1)-1
    if ind1(i+1)-ind1(i) > 20
       flag = [flag,i]; 
    end
end

%跳频周期
for i = 1:length(flag)
    if i == 1
       ind12(i) = ind1(flag(i)+1)-ind1(1); 
    else
       ind12(i) = ind1(flag(i)+1)-ind1(flag(i-1)+1); 
    end
end
cycle = floor(mean(ind12))+1;


for i = 1:length(t)-cycle
    cyclss(i) = 1000*(t(cycle+i)-t(i));
end

mean(cyclss) 

3.仿真效果

 A01-160