pulseshape.m

这个程序主要是实现空时编码的matlab编解码仿真。

function [s,t]=pulseshape(indata,fs,pulsetype,T)

%   [s,t]=pulseshape(indata,fs,pulsetype,T)
%
%	Output:
%	s		    - Symbols after pulsshaping and upsampling
%	t		    - Time
%
%   Input:
%   indata      - BPSK-modulated
%   fs          - Samplefrequency
%   pulsetype   - Decides which pulsform to be used
%                 pulsetype=1 => square 
%                 pulsetype=2 => rootraisedcosine
%                 pulsetype=3 => hamming
%                 pulsetype=4 => raisedcosine
%   T           - Symbolperiod
%
%   Short Theoretical Background for the Function:
%   
%   Upsamples indata by a factor of oversamp by insertion of oversamp-1 zeros 
%   and applies pulse shaping with a pulsshape according to the variable pulsetype.
%   
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
%%% Function part of simulation for Space-Time
%%% coding project, group Grey-2001.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%   Author: Fredrik Hansson
%   Date:2001-03-19
%   Version:1.0
%   Revision (Name & Date): FH and SU 21/3
%       1.1 SU  20010406    Added option: pulsetype=4 for Raised-Cosine pulseform.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
oversamp = fs*T;
L = length(indata);

if  pulsetype == 1                      % choose pulsetype
    p = ones(1,oversamp)/sqrt(oversamp);
elseif pulsetype == 2
    p = root_raised_cosine(oversamp);
elseif pulsetype == 3
    p = hamming(oversamp)';
elseif pulsetype == 4
    p = raised_cosine(oversamp);
end

%%%
%%% Zero insertion:
%%%

data_with_zeros = zeros(1,oversamp*L);
data_with_zeros(1:oversamp:end) = indata;  
 
%%%
%%% Filter with selected pulsetype, using convolution:
%%%

s = conv(p,data_with_zeros);
t = 0:T/oversamp:(L*T-T/oversamp); % upsampled time scale