Linear Frequency Modulated Waveform

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Jagadeeshvelan kumar
Jagadeeshvelan kumar on 20 Jul 2013
why LFM waveform has varying amplitude when i take step of phased.LinearFMWaveform
  3 Comments
Jagadeeshvelan kumar
Jagadeeshvelan kumar on 22 Jul 2013
Edited: Honglei Chen on 22 Jul 2013
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
Honglei Chen on 22 Jul 2013
added code format to the comment above.

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Answers (1)

Honglei Chen
Honglei Chen on 22 Jul 2013
Edited: Honglei Chen on 22 Jul 2013
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

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