Linear Frequency Modulated Waveform

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Jagadeeshvelan kumar 2013-7-20

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https://ww2.mathworks.cn/matlabcentral/answers/82657-linear-frequency-modulated-waveform

why LFM waveform has varying amplitude when i take step of phased.LinearFMWaveform

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Jagadeeshvelan kumar 2013-7-22

编辑：Honglei Chen 2013-7-22

在 MATLAB Online 中打开

clc;
clear all;
pd=0.9;
pfa=1e-6;
max_range=1000;   
range_res=0.5 ;
fc=35e9;
prop_speed = physconst('LightSpeed');
pulse_bw = prop_speed/(2*range_res);
pulse_width=1/pulse_bw;              
fs = 2*pulse_bw;
noise_bw =2*pulse_bw;
c=3e8;
lambda=c/fc;
time_bandwidth_product=100;
prf= prop_speed/(2*max_range);     
hw=phased.LinearFMWaveform('SampleRate',fs,'PulseWidth',time_bandwidth_product/pulse_bw,'PRF',prf,'SweepBandwidth',pulse_bw,'NumPulses',1);
x=step(hw);
plot(hw);

Honglei Chen 2013-7-22

added code format to the comment above.

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Answer 1

Honglei Chen 2013-7-22

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https://ww2.mathworks.cn/matlabcentral/answers/82657-linear-frequency-modulated-waveform#answer_92421

编辑：Honglei Chen 2013-7-22

在 MATLAB Online 中打开

The plot() function on LinearFMWaveform, plots only the real part of the waveform, so the amplitude is indeed varying.

If you are asking why in each period, the maximum amplitude seems to be varying, that is because in discrete time, you may not always be able to sample right at the peak in each period. However, if you plot

plot(abs(x))

You can see that the magnitude is constant.

HTH