Matlab Codes for Noise and Jammers

Replies

• 

  silverscorpion

  what exactly do you want? code for noise generation or noise removal..
  As to jammers, it's very easy. if you know the frequency you want to jam, you can generate some random signal of that frequency and greater amplitude. That's it.
  
  If you dont know the frequency, then it becomes somewhat more difficult. Then you have to use hardware also. It cant be done only with matlab code. ie, use your receiver and receive the signal. know the frequency components in it and then generate that frequency. Clear?
• 

  Vila

  Hii,
  
  I need matlab codes for noise generation and also codes for broadband noise jammer.
  
  Thank you...
• 

  silverscorpion

  hey you!
  
  I just answered your question and you are reposting the question again. I'll again tell you, we dont give you the code here. You do the code, if there are any problems, we'll be happy to help.
• 

  durga ch

  Vila

  Hii,
  
  I need matlab codes for noise generation and also codes for broadband noise jammer.
  
  Thank you...

  what type of noise are you refering to?
  gaussian?
• 

  Vila

  Hiii,
  
  Gaussian, AWGN or Broadband noise, either one can do..
  
  Thank you.
• 

  Vila

  Hiii,
  
  Mmm well i have some codes here, its shows errors. to whom i have to show them to get rectified? Do i just post the codes here?
  
  Thank you.
• 

  silverscorpion

  just post that section of the code which has errors in it. Or if it's ok for you, posting the full code is no harm, either.. Post it in this thread itself.
• 

  durga ch

  Vila

  Hiii,
  
  Mmm well i have some codes here, its shows errors. to whom i have to show them to get rectified? Do i just post the codes here?
  
  Thank you.

  If your matlab has communications tool box, you have function 'awgn' which generated white gaussian noise and adds it to your signal depending on the impedance and nosie DB
  
  may be you can search the 'help ' section in your matlab for 'awgn' command
  
  for more infomration you can as well refer to the MATLAB help link
  #-Link-Snipped-#
• 

  Vila

  This program should show the effect of Gaussian filter.
  
  %%%%%%%%%%%%% The main.m file %%%%%%%%%%%%%%%
  clear;
  % Parameters of the Gaussian filter:
  n1=10;sigma1=3;n2=10;sigma2=3;theta1=0;
  % The amplitude of the noise:
  noise=0.1;
  [w,map]=gifread('lena.gif');
  x=ind2gray(w,map);
  filter1=d2gauss(n1,sigma1,n2,sigma2,theta);
  x_rand=noise*randn(size(x));
  y=x+x_rand;
  f1=conv2(x,filter1,'same');
  rf1=conv2(y,filter1,'same');
  figure(1);
  subplot(2,2,1);imagesc(x);
  subplot(2,2,2);imagesc(y);
  subplot(2,2,3);imagesc(f1);
  subplot(2,2,4);imagesc(rf1);
  colormap(gray);
  %%%%%%%%%%%%%% End of the main.m file %%%%%%%%%%%%%%%
  
  
  
  
  When i tried to run them, it shows this error message:
  
  Error in ==> gaussian at 7
  [w,map]=gifread('lena.gif');
  
  Thanks for helping...
  
• 

  Vila

  These are another set of codes in which it should display Rayleigh function graph:
  
  
  %Initialization D=1 (D = interleaving depth)
  clear;
  Ts=1/1e3; % tx rate = 10k bps
  NA=10000;
  A=floor(rand(1,NA)+0.5);
  %A=randint(1,NA);
  input=A;
  G=[1 0 0; 1 0 1; 1 1 1];
  k=1;
  
  N=length(channel_output);
  SNRdB= -10:5:20;
  SNR=10.^(SNRdB/10);
  Counter=zeros(1,length(SNRdB));
  loop=0;
  
  %***************************************************************
  % AWGN + fading *
  %***************************************************************
  Fd=66; % Actual fading rate
  fm=round(Fd*NA*Ts);
  
  %Generate two inputs of 1 x N matrix
  xin=randn(1,(NA+2)*3);
  yin=randn(1,(NA+2)*3);
  
  %Loop for all values of frequencies and truncate at just before f=fm
  for f=1😔fm-1)
  filter(f)=1.5/(pi*fm*sqrt(1-(f/fm)^2));
  end
  for f=(fm-1)😔NA+2)*3
  filter(f)=0;
  end
  
  %Inputs of the filter is multiplied with the filter transfer function
  xout=xin.*filter;
  yout=yin.*filter;
  
  %Perform inverse Fourier Transform on both output
  xifft=real(ifft(xout));
  yifft=real(ifft(yout));
  
  % normaliation so that E{R^2}= 1 / in Watt = 0 dB
  std_x=std(xifft);
  std_y=std(yifft);
  xifft=xifft/std_x/sqrt(2);
  yifft=yifft/std_y/sqrt(2);
  
  %Sum the square the of the IFFT and take the square root of it
  rx=sqrt(xifft.^2+yifft.^2);
  
  %****************************************************************
  %Calculate for all value of SNRdB in AWGN + fading
  %****************************************************************
  loop=0;
  for b=sqrt(SNR) %b is the signal level
  loop=loop+1;
  dfad=0;
  for n=1😔NA+2)*3 %n = no of bits
  x=randn;
  t=channel_output(n);
  if t>=0.5
  a=b*rx(n);
  r=a+x;
  if r<0
  dfad=dfad+1; % error has occured, increase counter
  Df(n)=0;
  else
  Df(n)=1;
  end
  else
  a=(-b)*rx(n);
  r=a+x;
  if r>0
  dfad=dfad+1;
  Df(n)=1;
  else
  Df(n)=0;
  end
  end
  Counterf(loop)=dfad; % w/o decode
  end
  output=viterbi(G,k,Df); % E is output of decoder
  zf=0;
  v=1;
  for v=v:1:length(A);
  if xor(input(1,v),output(1,v))==1
  zf=zf+1;
  end
  end
  Counter_wcf(loop)=zf;
  end% loop for signal (b) in AWGN + fading
  
  
  %plot simulation in AWGN + fading without coding
  Pef=Counterf/N;
  %semilogy(SNRdB,Pef,'b');
  %hold on;
  %plot simulation in AWGN + fading with coding
  Pe1f=Counter_wcf/NA;
  save D1_66SNRdBPe1fPef
  %semilogy(SNRdB,Pe1f,'b'); %D=1 no interleaving
  %hold on;
  
  
  but when i tried running them, it shows this error message:
  
  Error in ==> Rayleigh at 12
  N=length(channel_output);
  
  Please help me..thank you
  
• 

  silverscorpion

  In the first piece of code, try using imread() instead of gifread(). I'm not sure if a function gifread() to specifically read gif files exist.
  
  In the second piece of code, you dont seem to have defined what is 'channel_output'. you have used channel_output as a function in the later part of the code, and in the top part, you have tried to find the length of a function. That might be the problem.
• 

  durga ch

  I dotn see channel_output being defined. Did yu put up the whole code mate?
• 

  Vila

  It gives the same error even if i use imread() instead of gifread()
  
  Yes whole code mate, how do i define the channel_output then?
• 

  durga ch

  Hi
  
  clear;
  Ts=1/1e3; % tx rate = 10k bps
  NA=10000;
  A=floor(rand(1,NA)+0.5);
  %A=randint(1,NA);
  input=A;
  G=[1 0 0; 1 0 1; 1 1 1];
  k=1;
  
  N=length(channel_output);
  SNRdB= -10:5:20;
  SNR=10.^(SNRdB/10);
  Counter=zeros(1,length(SNRdB));
  loop=0;
  
  if ts is your transmitted signal then your channle output should be a convolution of you input signal and noise.
  
  ie your channel output should be on lines of
  output = H * input;
  
  where H is is your channel matirx and inout in Tx
• 

  Vila

  Hiii thanks a lot,
  
  Now i have a set of coding over here but i dont know how to determine which one is the information signal and which one is the carrier signal, wheter xin, yin, xout or yout..and what is NA?
  
  
  %Initialization D=1 (D = interleaving depth)
  clear;
  Ts=1/1e3; % tx rate = 10k bps
  NA=1000;
  A=floor(rand(1,NA)+0.5);
  %A=randint(1,NA);
  input=A;
  G=[1 0 1 1 0 1 1; 1 1 0 0 1 0 1; 1 1 1 1 1 0 1];
  %G=[1 0 0; 1 0 1; 1 1 1];
  k=1;
  channel_output=cnv_encd(G,k,A);
  N=length(channel_output);
  SNRdB= -10:5:20;
  SNR=10.^(SNRdB/10);
  Counter=zeros(1,length(SNRdB));
  loop=0;
  L_one=length(G)-1;
  no_rows=size(G,1);
  encoder_output_bits=(NA+L_one)*no_rows;
  
  %***************************************************************
  % AWGN + fading *
  %***************************************************************
  Fd=2000; % Actual fading rate
  fm=round(Fd*NA*Ts);
  
  %Generate two inputs of 1 x N matrix
  xin=randn(1,encoder_output_bits);
  yin=randn(1,encoder_output_bits);
  
  %Loop for all values of frequencies and truncate at just before f=fm
  for f=1😔fm-1)
  filter(f)=1.5/(pi*fm*sqrt(1-(f/fm)^2));
  end
  for f=(fm-1):encoder_output_bits
  filter(f)=0;
  end
  
  %Inputs of the filter is multiplied with the filter transfer function
  xout=xin.*filter;
  yout=yin.*filter;
  
  %Perform inverse Fourier Transform on both output
  xifft=real(ifft(xout));
  yifft=real(ifft(yout));
  
  % normaliation so that E{R^2}= 1 / in Watt = 0 dB
  std_x=std(xifft);
  std_y=std(yifft);
  xifft=xifft/std_x/sqrt(2);
  yifft=yifft/std_y/sqrt(2);
  
  %Sum the square the of the IFFT and take the square root of it
  rx=sqrt(xifft.^2+yifft.^2);
  
  plot(xout);
  plot(yout);
  
  Thank you mate...
  
• 

  durga ch

  Vila

  Hiii thanks a lot,
  
  Ts=1/1e3; % tx rate = 10k bps
  NA=1000;
  A=floor(rand(1,NA)+0.5);
  %A=randint(1,NA);
  input=A;
  G=[1 0 1 1 0 1 1; 1 1 0 0 1 0 1; 1 1 1 1 1 0 1];
  k=1;
  channel_output=cnv_encd(G,k,A);
  
  

  hmm, tell me one thing has this code been picked off from the net?
  anyways
  A is your input signal. it s a randaom signal generated. NA can be any number and you rand 1,1000 .
  and your G is the convoluional encoder in polynomial representation
• 

  Vila

  Hiii...yes its from the net...if A is the input signal then how about xin and yin?
• 

  stylishdudevicky

  Hi,
  I know few people who can write any Matlab or programming codes as a pay service. contact them at #-Link-Snipped-#
  Hope this helps.
• 

  robben71

  Hi, does anyone have code for gray world and white point (image processing)?
• 

  KrishTCE

  Hi...... i need the verilog code for generating jamming signal......... can anyone tell me the logic for generating???
• 

  danish salim soonka

  i need to implement a jammer model can anyone help?