detector.m

这个程序主要是实现空时编码的matlab编解码仿真。

function [indata_est,training1_est, training2_est]=detector(inphase_symbols,training_length1,training_length2,model)

%   [indata_est,training1_est, training2_est]=detector(inphase_symbols,training_length1,training_length2,model)   
%
%	Output:
%	indata_est          - Estimated bits {0,1}
%   training1_est       - Estimated training bits sequence 1
%   training2_est	    - Estimated training bits sequence 2
%
%   Input:
%   inphase_symbols     - Downsampled inphase component 
%   training_length1    - Length of training sequence 1
%   training_length2 	- Length of training sequence 2
%   model			    - 0: no Alamouti (only 1 antenna), 1: Alamouti	 
%
%   Short Theoretical Background for the Function:
%   
%   Estimates the received bits from the inphase-component of 
%   the received BPSK-symbols. 
%   symbols < 0 => data_est = 0
%   symbols > 0 => data_est = 1
%   this is done by taking sign of inphase_symbols which gives
%   -ones and ones. By adding one and dividing by two zeros and ones are achieved.  
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
%%% Function part of simulation for Space-Time
%%% coding project, group Grey-2001.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%   Author:  Fredrik Hansson
%   Date:    2001-03-22
%   Version: 1.1
%   Revision (Name & Date & Comment):
%		SU 2001-03-25 Added parameteres: model and training_length2 for
%							the case of having two antennas sending with
%							one train-sequence each.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

data_est = floor((sign(inphase_symbols)+1)/2);   
if model == 0                                   % no alamouti coding 
   training1_est = data_est(1:training_length1);
   training2_est = 0;
   indata_est = data_est(training_length1+1:end);       
elseif model == 1                               % alamouti coding
   training1_est = data_est(1:training_length1);
   training2_est = data_est(training_length1+1:training_length1+training_length2);
   indata_est = data_est(training_length1+training_length2+1:end);
end