目录
 
方式1：每个频率持续一段时间
 
方式二：每个频率采样一个点
 

方式1：每个频率持续一段时间
 
 
% ==================================================
% 作者： jialf
% 时间： 2020/3/22
% 版本： V1
% =================FM线性调频仿真================
Fs = 30.72*10^6; %采样频率
period = 1000;   %每个频点的采样点数
t=1:period;      
N=20;            %频点个数
fm_i = zeros(1,N*length(t));
fm_q = zeros(1,N*length(t));
for n=1:N
   fm_i((n-1)*length(t)+1:(n-1)*length(t)+period) = cos(2*pi*t*n/period);
   fm_q((n-1)*length(t)+1:(n-1)*length(t)+period) = sin(2*pi*t*n/period);
end
plot_xy(fm_i,fm_q,0,Fs); 
 
方式二：每个频率采样一个点
 
 
% ==================================================
% 作者： jialf
% 时间： 2020/3/22
% 版本： V1
% =================FM线性调频仿真================
 Fs = 30.72*10^6;  %采样频率
 len = 30720;      %数据长度       
 f=0;              %频率变化间隔
 n=0;
 fm_i = zeros(1,len);
 fm_q = zeros(1,len);
 for t=0:1/Fs:(len-1)/Fs
    n=n+1;
    f=f+10;
    fm_i(n) = cos(2*pi*f*t);
    fm_q(n) = sin(2*pi*f*t);
 end
plot_xy(fm_i,fm_q,0,Fs); 
 
 

 
基于matlab的线性调频信号的仿真 
 
I存档编号________ 基于 MATLAB 的线性 调频信号的仿真教学学院 届 别 专 业 学 号 指导教师 完成日期 I 内容摘要：线性调频信号是一种大时宽带宽积信号。线性调频信号的 相位谱具有平方律特性，在脉冲压缩过程中可以获得较大的压缩比， 其最大优点是所用的匹配滤波器对回波信号的多普勒频移不敏感，即 可以用一个匹配滤波器处理具有不同多普勒频移的回波信号，这些都 将大大简化雷达信号处理系统，而且线性调频信号有着良好的距离分 辨率和径向速度分辨率。因此线性调频信号是现代高性能雷达体制中 经常采用的信号波形之一，并且与其它脉压信号相比，很容易用数字 技术产生，且技术上比较成熟，因而可在工程中得到广泛的应用。 关键词：MATLAB；线性调频；脉冲压缩；系统仿真II Abstract： Linear frequency modulation signal is a big wide bandwidth signal which is studied and widely used. The phase of the linear frequency modulation signal spectra with square law characteristics, in pulse compression process can acquire larger compression, its biggest advantage is the use of the matched filter of the echo signal doppler frequency is not sensitive, namely can use a matched filter processing with different doppler frequency shift of the echo signal, these will greatly simplified radar signal processing system, and linear frequency modulation signal has a good range resolution and radial velocity resolution. So linear frequency modulation signal is the modern high perance radar system often used in one of the signal wave, and compared with other pulse pressure signal, it is easy to use digital technologies to produce, and the technology of the more mature, so in engineering can be widely applied. Keywords：MATLAB, LFM, Pulse compression, System simulationIII 目 录 内容摘要I 关键词I Abstract .II Keywords II 1 绪论 .1 1.1引言 .1 1.2课题研究背景及意义 .1 1.3本文主要工作 .2 2 线性调频基本理论 .3 2.1线性调频原理简介 .3 2.2线性调频信号特点 .3 3 MATLAB 简介 5 3.1 MATLAB 的起源 .5 3.2 MATLAB 的应用领域 .5 3.3 MATLAB 的仿真方法 .6 4 线性调频脉冲压缩原理及实现 .10 4.1线性调频信号的数字脉冲压缩原理 .10 4.1.1匹配滤波器原理

clear;
B=20e6;%带宽
T=10e-6;%脉宽
f0=10e6;%中心频率
fs=100e6;%采样频率
N=round( T/(1/fs));%采样点数
t=linspace(-0.5*T,0.5*T,N);%时间
K=B/T;%调频斜率
x=exp(1j*2*pi*(f0*t+K*t.^2/2));%信号
% 线性调频信号
plot(t,real(x))
ff=-fs/2:fs/N:fs/2-fs/N;
plot(ff,abs(fftshift(fft(x))))

 
关键的问题在于采样点数应该是计算出来的，而不是自己随便定的
 

 
问题描述：
 
MATLAB关于产生线性调频信号的问题
 
t=10e-6; %线性调频信号时间长度
 
fs=40e6; %采样频率
 
ts=1/fs;
 
fc=9e6; %线性调频的起始频率
 
f0=10e6; %本振信号的中心频率
 
B=2e6; %线性调频信号调频带宽
 
ft=0:1/fs:t-1/fs; %调制信号,对于线性调频来说,调制信号就是时间序列
 
N=length(ft);
 
k=B/fs*2*pi/max(ft); %计算调制灵敏度
 
x1=modulate(ft,fc,fs,'fm',k);
 
最后的那句是什么意思,modulate函数的用法及个参数意思~
 
1个回答
 
分类：
 
英语
 
2014-12-07
 
问题解答：
 
我来补答
 
楼主要学会用MATLAB的help命令啊：
 
help modulate
 
MODULATE Signal modulation for communications simulations.
 
Y = MODULATE(X,Fc,Fs,METHOD,OPT) modulates the message signal X with a
 
carrier frequency Fc and sampling frequency Fs,using the modulation
 
scheme in METHOD.OPT is an extra sometimes optional parameter whose
 
purpose depends on the modulation scheme you choose.
 
Fs must satisfy Fs > 2*Fc + BW,where BW is the bandwidth of the
 
modulated signal.
 
METHOD MODULATION SCHEME
 
'am',Amplitude modulation,double side-band,suppressed carrier
 
'amdsb-sc' OPT not used.
 
'amdsb-tc' Amplitude modulation,double side-band,transmitted carrier
 
OPT is a scalar which is subtracted from X prior to
 
multiplication by the carrier cosine.It defaults to
 
min(min(X)) so the offset message signal is positive and
 
has a minimum value of zero.
 
'amssb' Amplitude modulation,single side-band
 
OPT not used.
 
'fm' Frequency modulation
 
OPT is a scalar which specifies the constant of frequency
 
modulation kf.kf = (Fc/Fs)*2*pi/max(max(abs(X))) by
 
default for a maximum frequency excursion of Fc Hertz.
 
'pm' Phase modulation
 
OPT is a scalar which specifies the constant of phase
 
modulation kp.kp = pi/max(max(abs(x))) by default for a
 
maximum phase excursion of +/-pi radians.
 
'pwm' Pulse width modulation
 
If you let OPT = 'centered',the pulses are centered on the
 
carrier period rather than being "left justified".
 
'ppm' Pulse position modulation
 
OPT is a scalar between 0 and 1 which specifies the pulse
 
width in fractions of the carrier period.It defaults to .1.
 
'qam' Quadrature amplitude modulation
 
OPT is a matrix the same size as X which is modulated in
 
quadrature with X.
 
If X is a matrix,its columns are modulated.
 
[Y,T] = MODULATE(...) returns a time vector the same length as Y.
 
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