How to save a loop data

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Bahaa Algebory
Bahaa Algebory 2016-10-22
评论： Walter Roberson 2016-10-24
Hi guys, I have a for loop, but every iteration overwrites the variable(max_run), and I have only the final data left. How can I save data from every loop? I saw some other questions like my issue, but I always get an error"Improper assignment with
%%BPSK Generation
clear all; close all; clc;
N = 2*10^4; % number of bits or symbols
ip = rand(1,N)>0.5; % generating 0,1 with equal probability
s = 2*ip-1; % BPSK modulation 0 -> -1; 1 -> 1
%%Prepare transmitted signal
m=2; % oversampling factor
beta=0.3; % rolloff parameter for SRRC
l=100; % 1/2 length of pulse shape (in symbols)
chan=[1]; % T/m "channel"
toffset=-0.5; % initial timing offset
pulshap=srrc(l,beta,m,toffset); % SRRC pulse shape
sup=zeros(1,N*m); % upsample the data by placing...
sup(1:m:end)=s; % ... p zeros between each data point
hh=conv(pulshap,sup); % ... and pulse shape
r1=conv(hh,chan); % ... to get received signal
%%Noise Generation
SNRdB=1:2:13; % Signal to Noise Ratio
SNR=10.^(SNRdB/10);
for cv=1:length(SNR);
no=sqrt((1/SNR(cv)))*randn(1,40400); % Noise generation
r=r1+no; % Adding the noise to the received signal
%%Matched Filter & Convolution process
matchfilt=srrc(l,beta,m,0); % filter = pulse shape
x=conv(r,matchfilt); % convolve signal with matched filter
%%Run clock recovery algorithm
tnow=2*l*m+1; tau=0; xs=zeros(1,N); % initialize variables
tausave=zeros(1,N); tausave(1)=tau; i=0;
mu=0.05; % algorithm stepsize
delta=0.1; % time for derivative
while tnow<length(x)-2*l*m % run iteration
i=i+1;
xs(i)=interpsinc(x,tnow+tau,l); % interpolated value at tnow+tau
x_deltap=interpsinc(x,tnow+tau+delta,l); % get value to the right
x_deltam=interpsinc(x,tnow+tau-delta,l); % get value to the left
dx=x_deltap-x_deltam; % calculate numerical derivative
tau=tau+mu*dx*xs(i); % alg update (energy)
tnow=tnow+m; tausave(i)=tau; % save for plotting
indexmin = find(tausave >= 0.5); % finding iteration value..
max_run = min(indexmin) % automaticlly
end
% Plot results
figure, subplot(2,1,1), plot(xs(1:i-2),'b.');
legend([ 'SNR=' int2str(SNR(cv))]); % plot constellation diagram
title('constellation diagram');
ylabel('estimated symbol values')
subplot(2,1,2), plot(tausave(1:i-2))
ylabel('offset estimates'), xlabel('iterations')
legend([ 'SNR=' int2str(SNR(cv))]);
end

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采纳的回答

Walter Roberson
Walter Roberson 2016-10-23
max_run(i) = min(indexmin);
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Bahaa Algebory
Bahaa Algebory 2016-10-24
编辑：Walter Roberson 2016-10-24
Walter, thank you again,
Yes, there are values for 'indexmin'. This is the code of 'srrc' function.
function s=srrc(syms, beta, P, t_off);
% s=srrc(syms, beta, P, t_off);
% Generate a Square-Root Raised Cosine Pulse
% 'syms' is 1/2 the length of srrc pulse in symbol durations
% 'beta' is the rolloff factor: beta=0 gives the sinc function
% 'P' is the oversampling factor
% 't_off' is the phase (or timing) offset
if nargin==3, t_off=0; end; % if unspecified, offset is 0
k=-syms*P+1e-8+t_off:syms*P+1e-8+t_off; % sampling indices as a multiple of T/P
if (beta==0), beta=1e-8; end; % numerical problems if beta=0
s=4*beta/sqrt(P)*(cos((1+beta)*pi*k/P)+... % calculation of srrc pulse
sin((1-beta)*pi*k/P)./(4*beta*k/P))./...
(pi*(1-16*(beta*k/P).^2));
Actually, now I'm required to find the value of offset point" Y axis" where the curve becomes stable for the same value which is about "0.5" by depending on iteration values. So, any help will be appreciated.
Walter Roberson
Walter Roberson 2016-10-24
Your line
xs(i)=interpsinc(x,tnow+tau,l); % interpolated value at tnow+tau
uses an undefined routine interpsinc . I grabbed interpsinc from the File Exchange but you appear to be asking to interpolate all the x values at time tnow+tau and you have over 40000 x values so the result is over 40000 results, which do not fit into the single location xs(i)

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