升余弦滤波器 matlab代码

昵称4074875 2010-11-12

展开全文

关于信号波形成型：
     升余弦滤波器
(1) 升余弦滤波器的 matlab函数－－ rcosine, rcosflt
R;g2PsDpJ H'JK0     这个问题的代码已经在 “关于‘Matlab Demos’的学习”项目中得到了总结。
Iwd(];R)H0     优点：参数明了，容易设置；
     缺点：实现方法不透明。

(2) 升余弦滤波器的 matlab代码
4[2J#}!O-Ue0 升余弦公式：
P%l`J%[)\].{0

程序代码之一：
gZ!}%?;U'M0% -------------------------------------------------------------------------
n0l:E-^ TS0% File: c5_rcosdemo.m中国通信网－无限分享M w%Z}c
% -------------------------------------------------------------------------
% Software given here is to accompany the textbook: W.H. Tranter,
*mx p;o t1T\;jJ4m@0% K.S. Shanmugan, T.S. Rappaport, and K.S. Kosbar, Principles of
A^(x7O1D%_0% 《 Communication Systems Simulation with Wireless Applications 》
gzs*E*q@4Z0% Prentice Hall PTR, 2004.
% -------------------------------------------------------------------------
+O"wb |nz6n#j1f0% 用卷积的办法求升余弦滤波器的冲击响应
'Wp a B4I#P0% -------------------------------------------------------------------------
% revised by lavabin 2006.08.04
% -------------------------------------------------------------------------
clc;clear all;close all;echo off;tic;

% -------------------------------------------------------------------------
za2Xh m0% Parameter Definition
% -------------------------------------------------------------------------
k = 10; % Samples per symbol

m = 4;
% (1) time span for the display or impulse response width
9\FNgY+yE$?u0% 正半轴时间轴的跨距，单位：符号周期，这里缺省的符号周期是default T = 1，
% 这里m = 4,则左右跨度4个符号周期。
!K$rFyc0rp0% (2) Delay
% 相位延迟的问题，要产生真正的因果信号，输入信号必须是经过延时的，m是延时参数之一

beta = [ 0.32 0.80 1.00 ] ; % Bandwidth Factor or Roll-Off Factor

for ii = 1:length(beta)
@d?UE3E4p'l!K"{0h      = rcos(k,m,beta(ii));      % impulse response
u j _9[4E I4^#b0in     = zeros(1,101); in(11) = 1;     % input
3U5o%T:^9i*l0out(ii,:) = conv(in,h);     % output
end

t = 0:0.1:10; % time vector for plot
"_ Z+Ui,Y$t0% 关于时间index的问题,这里的时间并不是按照前面的在t＝11*T＝11处的标准来定义的
#vs2^d8h u_xd?0% 这里的时间仅仅是为了显示图形的时候保持图形对称

figure;
O-UO I"T-d9J(p0plot(t,out(1,1:101),'r*-',t,out(2,1:101),'bo-',t,out(3,1:101),'k+-');
grid on;
!quG@h*lWyw3G0xlabel('Time');
ylabel('Amplitude');title('Impulse Response of Rcosine');
'x4R7qQU r0legend('Roll-Off = 0.32','Roll-Off = 0.80','Roll-Off = 1.00' );

simulation_time = toc
[J:\~SP t0% -------------------------------------------------------------------------
P4[a}6q y.NL$O~0% End of script file.
% -------------------------------------------------------------------------
X&SV6XS/@*G0

% -------------------------------------------------------------------------
y+EK%c4z nr/`0% File: rcos.m
N/a?pn6bhC0% -------------------------------------------------------------------------
qW#wDF!};U?l0% Software given here is to accompany the textbook: W.H. Tranter,
+YI i/uc!G2|0% K.S. Shanmugan, T.S. Rappaport, and K.S. Kosbar, Principles of
nHv&f%_5M U0% 《 Communication Systems Simulation with Wireless Applications 》
{r X\T0% Prentice Hall PTR, 2004.中国通信网－无限分享 j"tl+\h
% -------------------------------------------------------------------------
W^1aA(|9O0%                                       revised by lavabin 2006.08.04
% -------------------------------------------------------------------------
`]3BS ^0function h = rcos(k,m,beta)
% k - samples per symbol
R3m&xs5T T*~0% m - delay is mT
% beta - bandwidth factor
% default T = 1
G:}IigNj0beta = beta;
.d6Wa$|D U0n    = 0:2*m*k;           %
z    = (n/k) - m + eps;   % time: t
t1   = cos(beta*pi*z);
t2   = sin(pi*z)./(pi*z);
t3   = 1 - 4*(beta^2)*z.^2;
c'v` p8y@_@0h    = t2.*t1./(t3);

length(n)
length(z)

if beta == 0.32
{-il9y"o:j1J1`?0figure;
subplot(211);
plot(n,h,'ro-');grid on;
:GYaw f*Q!QBKI0title('n = 0:2*m*k');

subplot(212);
? r fV5^7i0plot(z,h,'ro-');grid on;
)s!k]%G R:p0iA0title('z = (n/k) - m + eps');
end

% -------------------------------------------------------------------------
% End of function file.
Li\L N6q0% -------------------------------------------------------------------------