linear chirp signal generation ?

Question

Aniket 2013-2-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/62313-linear-chirp-signal-generation

评论： Neal Bambha 2019-12-16

hello i don't want to use chirp inbuilt function and i have written a code for chirp. could any one tell me is the code is correct ? i have simulate it and getting plot but at instantaneous time t1, I am not getting frequency change.

i have written a code according to equation of chirp signal generation.

please tell me this is correct ?

*****************************************

f1 =10;

f2 = 50 ;

t =0:0.001:20;

t1 = 10;

alpha = (f2-f1)/t1;

f= (alpha)*t + f1;

xx =1*cos(f);

plot (t,xx);

**********************************************

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Neal Bambha 2019-12-16

This is not the correct expression for a linear chirped signal. See the wikipedia page for "Chirp" There is a t-squared term in the sine. Otherwise you will not have the correct spectrum

chirp_slope = (f2 - f1)/t(end);

chirp_signal = sin(2*pi*(0.5*chirp_slope*t.^2 + f1*t));

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Answer 1

Youssef Khmou 2013-2-5

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https://ww2.mathworks.cn/matlabcentral/answers/62313-linear-chirp-signal-generation#answer_73857

编辑：Youssef Khmou 2013-2-5

在 MATLAB Online 中打开

hi, try this :

 Fs=1000; % sample rate 
tf=2; % 2 seconds
t=0:1/Fs:tf-1/Fs;
f1=100;
f2=400; % start @ 100 Hz, go up to 400Hz
semi_t=0:1/Fs:(tf/2-1/Fs);
sl=2*(f2-f1/2);
f1=f1*semi_t+(sl.*semi_t/2);
f2=f1(end)+f2*semi_t-sl.*semi_t/2;
f=[f1 f2];
y=1.33*cos(2*pi*f.*t);
plot(t,y)

To check the Amplitude spectrum (100Hz,400Hz), try my submission : http://www.mathworks.com/matlabcentral/fileexchange/40002-psd-power-spectral-density-and-amplitude-spectrum-with-adjusted-fft

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Atilla Golan 2018-1-21

编辑：Atilla Golan 2018-1-21

Hi Youssef, Can we try up-going and down going chirp together? (without using chirp function on Matlab). In a time range of [1.2s 2.7s] (for example) my function should go up 0.6s (since 1.2s to 1.8s) and go down for the rest (since 1.8s to the end:2.7s). I mean in a constant frequency range, function goes up and down during time like quadratic chirp function but without using chirp.

Dhananjay Singh 2019-2-25