the purpose of this code segment

I'm trying to understand the purpose of this code segment

binary_data=kron(ones(1,ratio),binary_data)';

binary_data=binary_data(:);

plot(binary_data);

here ratio = sample_rate/bit_rate and binary_data is a sequence of bits which are converted from a string of text

Is it for NRZ modulation? If it is, what actually happens in detail?

Answer 1

[Sriram Tadavarty]

Hi Oai,

The placed code just repeats the binary data by the ratio provided. It is a sort of upsampling when the binary_vector is column, and repetition of binary_vector if the input is row vector. But not NRZ modulation, since, 0 is not placed as -1.

ratio = 100;
binary_data = [1;1;0;1;0];
binary_data=kron(ones(1,ratio),binary_data)'; % This performs kronecker product and performs transpose
binary_data=binary_data(:); % This makes it to a single column vector
plot(binary_data); % Plots the code

For more details on kroncker product, look at kron page.

For simple exaplanation of what that the 3rd line in above does is below:

% Assume ratio is 2, binary data is [1;1;0]
kron([1 1],[1;0;1])' % kron([a1 a2],B) and then transpose
% This will give a matrix as such
% [a1*B a2*B] => [B B]'
% kron output is
% [1 1;
%  1 1;
%  0 0];
% Transpose the kron output
%  [1 1 0;
%   1 1 0];
% Now make it column vector with command(:)
% Output is [1 1 1 1 0 0]'

% For a case of row vector [1 1 0]
% Output is
% [1 1 0 1 1 0]'

Hope this helps.

Regards,

Sriram

[Oai Vu]

Thank you very much for your help!