Question

fftseq()

%Matlabel demonstration script for DSP modulation. %The message signal is + for 0<t<t0/3,-1 for t0/3<t<2t0/3,and zero %otherwise. clear echo off t0=0.15; ts=0.001; fc=250; snr=10; fs=1/ts; df=0.3; t=(0:ts:t0); snr_lin=10^(snr/10... %Matlabel demonstration script for DSP modulation.
%The message signal is + for 0<t<t0/3,-1 for t0/3<t<2t0/3,and zero
%otherwise.
clear
echo off
t0=0.15;
ts=0.001;
fc=250;
snr=10;
fs=1/ts;
df=0.3;
t=(0:ts:t0);
snr_lin=10^(snr/10);
%message signal
m=[ones(1,t0/(3*ts)),-1*ones(1,t0/(3*ts)),zeros(1,t0/(3*ts)+1)];
c=cos(2*pi*fc.*t); %carrier signal
u=m.*c; %modlated signal
[M,m,df1]=fftseq(m,ts,df);%fourier transform
M=M/fs; %scaling
[U,u,df1]=fftseq(c,fs,df);%Fourier transform
U=U/fs; %scaling
[C,c,df1]=fftseq(c,ts,df); %Fourier transform
f=[0:df1:df1*(length(m)-1)]-fs/2;%freq.vecror
signal_power=spower(u(1:length(t)));%power in modulaed signal
noise_power=signal_power/snr_lin;%compuer moise power
'显示信号功率噪声功率'
pause %press a key to show the modulated signal power and the noise power
signal_power
noise_power
'显示基带信号波形图'
Pause %press any key to see plot of the message
clf
figure(1)
plot(t,m(1:length(t)))
xlabel('time')
tile('The message signal')
'显示载波信号调制信号波形图'
Pause %press any key to see plot of the carrier and the modulaed signal
figure(2)
subplot(2,1,1)
plot(t,c(1:length(t)))
xlabel('Time')
title('The carrier')
subplot(2,1,2)
plot(t,u(1:length(t)))
xlabel('Time')
title('The modulated signal')
'显示基带信号调制信号频谱图'
pause %press any key to see plots of the magnitude of the message and the modulated signal in the frequency domain.
figure(3)
subplot(2,1,1)
plot(f,abs(fftshift(M)))
xlabel('frequency')
title('spectrum of the message signal')
subplot(2,1,2)
plot(f,abs(fftshift(U)))
title('spectrum of the modelated signal')
xlabel('frequency')

程序运行起提示说ftseq()没定义谁能给客运行程序

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Answer 1

%matlab面没fftseq（）函数需要自编写编写M文件放程序目录行
% MATLAB函数fftseq.m间序列m采间隔ts要求频率辨率df作输入度2幂序列
% 序列FFT(M)所要频率辨率
function [M,m,df]=fftseq(m,ts,df)
% [M,m,df]=fftseq(m,ts,df)
% [M,m,df]=fftseq(m,ts)
% FFTSEQ Generates M,the FFT of the sequence m.
% The sequence is zero-padded to meet the required frequency resolution df.
% ts is the sampling interval.The output df is the final frequency resolution.
% Output m is the zero-padded version of input m,M is the FFT.
fs=1/ts;
if nargin == 2
    n1=0;
else
    n1=fs/df;
end
n2=length(m);
n=2^(max(nextpow2(n1),nextpow2(n2)));
M=fft(m,n);
m=[m,zeros(1,n-n2)];
df=fs/n;
end