hrollfcoef.m

上传的是一个16Qam预失真处理的程序

% hrollfcoef.m
%
% Generate coefficients of Nyquist filter



function [xh] = hrollfcoef(irfn,ipoint,sr,alfs,ncc)

%******************** variables ***************************

% irfn   : Number of symbols to use filtering
% ipoint : Number of samples in one symbol 
% sr     : symbol rate
% alfs   : rolloff coefficients
% ncc    : 1 - transmitting filter 0 - receiving filter

%**********************************************************

xi = zeros(1,irfn*ipoint+1);
xq = zeros(1,irfn*ipoint+1);

point = ipoint;
tr = sr;
tstp = 1.0 ./ tr ./ ipoint;
n = ipoint .* irfn;
mid = ( n ./ 2 ) + 1;
sub1 = 4.0 .* alfs .* tr;           % 4 * alpha * R_s

for i = 1:n
    icon = i - mid;
    ym = icon;
    
    if icon == 0.0
        xt = (1.0-alfs + 4.0.*alfs./pi) .* tr;     % h(0)
    else
        sub2 = 16.0.*alfs.*alfs.*ym.*ym./ipoint./ipoint;
        if sub2 ~= 1.0
            x1 = sin(pi*(1.0-alfs)/ipoint*ym)./pi./...
                 (1.0-sub2)./ym./tstp;
            x2 = cos(pi*(1.0+alfs)/ipoint*ym)./...
                 pi.*sub1./(1.0-sub2);
            xt = x1 + x2;                      % h(t)
        else                                   % ( 4alphaRst )^2 = 1
            xt = alfs.*tr.*((1.0-2.0/pi).*cos...
                (pi/4.0/alfs)+(1.0+2.0./pi).*sin...
                (pi/4.0/alfs))./sqrt(2.0);
        end                                     % if sub2 ~= 1.0
    end                                         % if icon == 0.0
    
    if ncc == 0                           % in the case of receriver
        xh(i) = xt ./ ipoint ./ tr;       % normalization
    elseif ncc == 1                       % in the case of transmitter
        xh(i) = xt ./ tr;                 % normalization
    else
        error('ncc error');
    end                                    % if ncc == 0
end                                        % for i = 1:n

%******************** end of file ***********************************