fine_sync_block.m

来自「source Matlab traites the UWB」· M 代码 · 共 44 行

function [fine_sync_index] = fine_sync(rx_down,corr_template,thld,...
                blocks_per_code_symbol,code_len,coarse_sync_index,PLOT_DEBUG);
    
 
    %from -block to + 2blocks
    corr3 = conv(rx_down, fliplr(corr_template));
    corr3 = corr3(length(corr_template):length(corr_template)+blocks_per_code_symbol*4);
    %[max_corr4, ind_corr4] = max(corr3(blocks_per_code_symbol:2*blocks_per_code_symbol));
    
    %the max cannot be in last part
    [max_corr4, ind_corr4] = max(corr3(1:end-blocks_per_code_symbol));
    
    %ind_corr4 = ind_corr4 + blocks_per_code_symbol - 1;
    
    %we now go backwards through the correlation until we find one sample
    %that is not above the threshold, the max number of steps we go back is
    %blocks_per_code_symbol/2
    current_index = ind_corr4;
    t0_index = ind_corr4;
    for i=1:floor(blocks_per_code_symbol/2)
        current_index = current_index - 1;
        %wrap around if it goes over the beginning
        if(current_index == 0)
            break;
        end
        if(corr3(current_index) >= thld && corr3(current_index)>corr3(current_index+blocks_per_code_symbol))
            t0_index = current_index;
        end
    end
    fine_sync_index = coarse_sync_index - blocks_per_code_symbol + t0_index - 1;

    
%     if(PLOT_DEBUG)
%         figure
%         plot(corr3)
%         hold on
%         plot(thld*ones(1,length(corr3)),'m')
%         line([t0_index t0_index],[0 max(corr3)],'Color','g')
%         line([ind_corr4 ind_corr4],[0 max(corr3)],'Color','y')
%     end


return;