function y = echo( x,k,d )

len     = length(x);

y  = zeros(1, (len+d));


for n=1:1:(len+d)
    
    if (n > len)
        tmpA = 0;
    else
        tmpA = x(n);
    end;
    
    if ((n-d) <= 0)
        tmpB = 0;
    else
        tmpB = k * x(n-d);
    end;
    

    
    y(n) = tmpA + tmpB;


end