How can I divide a signal into blocks?

3 次查看（过去 30 天）
zayed
zayed 2011-12-11
I have a noise signal and I want -for some integer K- to break the signal into blocks of K samples, such that the first N samples make up the first block, the next K samples make up the second block, and so on,as below.I want to know if this algorithm correct or not :
x = radar_noise; % input signal
K = 1000; % K CAPITAL is Block Size
L = length(x) - mod(length(x),K); % only full blocks
zk = reshape(x(1:L), K, []);
%M=zeros(K,K); % M ZEROS covariance matrix L*L
M=[];
for i=1:size(zk,1) % LOOP covariance matrix calculation
Mz=zk(i,:)*zk(i,:)'; %
M=M+Mz;
end
M=M/K;

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2011-12-11
x = radar_noise; % input signal
K = 1000; % K CAPITAL is Block Size
L = length(x) - mod(length(x),K); % only full blocks
zk = reshape(x(1:L), K, []);
This will create zk with each block going down a columns, as you have in your existing code.
It appears to me that in your existing code, once calculate K and L, you then immediately use them with their opposite purposes, using K as if it the number of blocks and using L as if it is a block size.
  6 个评论
显示 4更早的评论
Walter Roberson
Walter Roberson 2011-12-11
You are still confusing block size and number of blocks. zk() has blocks running down the columns, and since you defined the size of the block as being K, size(zk,1) is going to be K. Your vector zk(:,i) is then going to be K by 1, so its conjugate transpose zk(:,i)' would be 1 by K, and the matrix multiplication of (K by 1) by (1 by K) will give you a K by K output. You are then trying to add that K x K output to an array that you defined as L x L.
I am not at all sure that you are calculating your covariance matrices the way you want, and I do not know why you would sum them, but that is a different matter.
zayed
zayed 2011-12-11
I have edited the code ,and it's run ok,but M is 1000*1000 with the same value (1.1180e+001) in all the matrix which is wrong.I don't know why.how can i get reasonable output.

请先登录，再进行评论。

更多回答（1 个）

Image Analyst
Image Analyst 2011-12-11
What do you want to do with each block? If you want each block to just be a row in a new 2D matrix, simply call
zk = reshape(x, [K, L]);
  2 个评论
Walter Roberson
Walter Roberson 2011-12-11
The floor() in the definition of L shows us that he does not expect that x is necessarily an exact multiple of K in length; in that situation, the plain resize() would fail as K*L might not be length(x)
zayed
zayed 2011-12-11
I want make a matrix out of our signal with one block of the signal per column.But first need to discard all samples beyond the first block_size*number_of_blocks samples of the input signal. reshape this shorter signal into a matrix with block_size rows and number_of_blocks columns.Also assign the output of reshape to something!

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Correlation and Convolution 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by