pulseshapefilter.m

脉冲整形的ＦＩＲ滤波器

function [y] = pulseShapeFilter (t)
%PULSESHAPEFILTER - TD-SCDMA pulse shape filter impulse response
%
% Syntax:   [y] = pulseShapeFilter (t)
%
% Inputs:
%   t           - Time values (seconds)
%
% Outputs:
%   y           - Impulse response amplitude
%
% Example: 
%   None
%
% Notes:
%   See Section 6.8.1 Transmit pulse shape filter in:
%
%       ETSI/3GPP, "Universal Mobile Telecommunications System (UMTS);
%       UTRA (BS) TDD: Radio transmission and reception (3GPP TS 25.105
%       version 5.2.0 Release 5)", ETSI TS 125 105, V5.2.0, September 2002
%

% Multiple Access Communications (MAC) Limited
% (c) Copyright 2006 MAC Ltd, all rights reserved

% Created by tnj (tnj-pc) on 24-Apr-2006 at 14:30:31.
% MatLab version 7.0.4.365 (R14) Service Pack 2
% $Revision: 2$
% $Author: Tim James$
% $Date: 13/06/2006 10:41:32$

% RRC definition
Tc = 1/1.28e6;
alpha = 0.22;

% Catch when t == 0 to avoid divide by zero issue
t (abs (t) < eps) = eps;

% Impulse response
y_num = sin ( pi * ( 1 - alpha ) * t / Tc ) + ...
    4 * alpha * t .* cos ( pi * ( 1 + alpha ) * t / Tc ) / Tc;
y_den = pi * t .* ( 1 - ( 4 * alpha * t / Tc ).^2 ) / Tc;
y = y_num ./ y_den;