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%Correction by GB 16.1.98:
%sqrt was not considered !
%Correction done for FIR only
function [y, t] = rcosfltk(x, Fd, Fs, type_flag, R, Delay, tol)
%RCOSFLT Filters the input signal using raised cosine filter.
% Y = RCOSFLT(X, Fd, Fs) filters the input signal X using raised cosine
% (R-C) FIR filter. The sample frequency for X is Fd (Hz). The sample
% frequency for Y is Fs. Fs must be larger than Fd. Fs/Fd must be an
% integer. The rolloff factor R is a default of .5. The time delay is a
% default of 3. The extra delay has been taken off from output Y,
% such that offset Fs/Fd - 1 is the best decision point (such as used
% in function MODMAP). The row number (or vector length) of Y is Ys/Yd
% times that of X's.
%
% Y = RCOSFLT(X, Fd, Fs, TYPE_FLAG) gives specific computation
% instruction. TYPE_FLAG is a string, which can be one of the following.
% 'fir' Use FIR R-C filter (default).
% 'iir' Use IIR R-C filter.
% 'normal' Use normal R-C filter (default), in contrast to 'qart'.
% 'sqrt' Use square root raised cosine filter.
% 'wdelay' Keep the full length of the filtered result, in which case
% the row number (or vector length) of Y is
% (length_of_X + DELAY)*Fs/Fd. The value DELAY is a default of
% 3. The function default has had the delay cut off from
% the output.
% 'Fs' X is input with sample frequency Fs. In this case, only
% elements X(i*Fs/Fd+1,:) are used in the calculation. All
% others are discarded.
% 'filter' Means filter is provided in this function call. When
% TYPE_FLAG contains 'filter', the calling format is
% Y = RCOSFLT(X, Fd, Fs, TYPE_FLAG, Delay, NUM).
% When TYPE_FLAG contains both 'filter' and 'iir', the calling
% format is Y = RCOSFLT(X, Fd, Fs, TYPE_FLAG, DELAY, NUM, DEN).
% where NUM and DEN are numerator and denominator of raised
% cosine filter. DELAY is the filter time delay is 1/Fd steps.
% If default DELAY has been used in the raised cosine design,
% use an empty matrix here. The raised cosine filter can be
% designed using function RCOSINE.
% 'default' Use all default values.
% TYPE_FLAG can be a combination of the above string with a '/' as
% separation. For example, TYPE_FLAG = 'iir/sqrt'.
%
% Y = RCOSFLT(X, Fd, Fs, TYPE_FLAG, R) gives rolloff factor. In
% general, it is a real number in range [0, 1].
%
% Y = RCOSFLT(X, Fd, Fs, TYPE_FLAG, R, DELAY) gives the delay in the
% measure of 1/Fd time steps. DELAY should be a positive integer.
% DELAY/Fd will be the time delay in the raised cosine filter design.
% If the default time delay is used, assign an empty matrix for DELAY.
%
% Y = RCOSFLT(X, Fd, Fs, TYPE_FLAG, R, DELAY, TOL) provides the
% tolerance in IIR filter design. The default value is .01.
%
% [Y, T] = RCOSFLT(...) outputs the time vector.
%
% See also RCOSINE.
% Wes Wang 1/19/95, 10/11/95.
% Copyright (c) 1995-96 by The MathWorks, Inc.
% $Revision: 1.1 $ $Date: 1996/04/01 18:02:18 $
%default tolerance
if nargin < 7
tol = .01;
end;
%default delay
if nargin < 6
Delay = 3;
elseif isempty(Delay)
Delay = 3;
elseif Delay <= 0
error('DELAY must be a positive integer in RCOSFLT.')
elseif ceil(Delay) ~= Delay
error('DELAY in RCOSFLT must be an integer.')
end;
%default rolloff factor
if nargin < 5
R = .5;
elseif R < 0
error('The Rolloff factor in RCOSFLT cannot be a negative number.')
end;
%default type_flag
if nargin < 4
type_flag = '';
elseif ~isstr(type_flag) & ~isempty(type_flag)
error('TYPE_FLAG in RCOSFLT must be a string.');
end;
%not enough input varible.
if nargin < 3
error('Not enough input variable for RCOSFLT.')
end;
%process the inptu variable x
if isempty(x)
y = [];
return;
end;
[len_x_o, wid_x_o] = size(x);
if min(len_x_o, wid_x_o) == 1
x = x(:);
end;
[len_x, wid_x] = size(x);
FsDFd = Fs/Fd;
if ceil(FsDFd) ~= FsDFd
error('Fs/Fd must be an integer.')
end;
type_flag = lower(type_flag);
%filter type.
if findstr(type_flag, 'sqrt')
filt_type = 'sqrt';
else
filt_type = 'normal';
end;
%design the filter.
if findstr(type_flag, 'fir')
if findstr(type_flag, 'filter')
if nargin < 5
error('Not enough input variable, FIR filter has to be assigned.')
else
num = R;
end
else
num = rcosfir(R, Delay, FsDFd, 1/Fd, filt_type)
end;
den = 1;
else
if findstr(type_flag, 'filter')
if nargin < 6
error('Not enough input variable, IIR filter has to be assigned.')
else
num = R;
den = Delay;
end
else
[num, den] = rcosiir(R, Delay, FsDFd, 1/Fd, tol);
end;
end;
%make the x to have the sample time Fs
if findstr(type_flag, 'fs')
xx = zeros(len_x+Delay*FsDFd, wid_x);
for i = 1 : FsDFd : len_x
xx(i, :) = x(i, :);
end;
else
xx = zeros((len_x+Delay)*FsDFd, wid_x);
for i = 1 : len_x
xx((i-1)*FsDFd+1, :) = x(i, :);
end;
end;
%filtering
for i = 1:wid_x
xx(:, i) = filter(num, den, xx(:, i));
end;
cut_length_b = (Delay - 1) * FsDFd + 2;
cut_length_e = size(xx, 1) - (FsDFd - 1);
t = [0:size(xx, 1)]/Fs;
if nargout < 1
% plot the result in comparing the input digit
xx = xx(cut_length_b:cut_length_e, :);
t = t(cut_length_b : cut_length_e);
if isempty(findstr(type_flag, 'Fs'))
yy = zeros((len_x)*FsDFd, wid_x);
for i = 1 : len_x
if i == 1
yy((i-1)*FsDFd+1:i*FsDFd, :) = ones(FsDFd, 1) * x(i, :);
else
yy((i-1)*FsDFd+1:i*FsDFd, :) = x(i*ones(1,FsDFd), :);
end;
end;
x = yy;
clear yy
end;
if (size(x, 2) == 1) | (size(x, 2) > 16)
plot(t, [xx x])
else
col='ymcrgbw';
plt = [];
for i = 1 : size(x, 2)
if i > 1
plt = [plt, ',t,[xx(:,', num2str(i), '),x(:,', num2str(i), ')],''', col(rem(i-1,7)+1),''''];
else
plt = 't,[xx(:,1), x(:,1)],''y''';
end;
end;
plt = ['plot(', plt, ')'];
eval(plt);
ylabel('Same color for original-filted pair')
end;
title('Raised cosine filted signal v.s. input signal.')
xlabel('Time (sec, original signal shifted)')
elseif findstr(type_flag, 'wdelay')
y = xx;
else
y = xx(cut_length_b:cut_length_e, :);
t = t(cut_length_b : cut_length_e);
end;
%--end of rcosflt.m--