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Doppler Effect in MATLAB

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MHanif

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I want to simulate multi-path fading channels in Matlab with doppler. But to my surprise, I found that Doppler introduces an AM modulation in the signal.
I used the rayleighchan and ricianchan for mimicing the multi-path effects but both give the same AM modulation of the signal with the sinusoid of the frequency fd which is parameter in the ricianchan and rayleighchan.

Kindly let me know that

i) Does Doppler effect change the amplitude?
ii) If yes how to cope with that.

Best regards.
 

MHanif

Mathematically, Doppler's Effect is independent of Amplitude.
As amplitude represent intensity, so in some cases Doppler's shift may effect Amplitude.
Hoping this explanation to be useful to some extent

Regards
Adeel
 

adeel.sid said:
As amplitude represent intensity, so in some cases Doppler's shift may effect Amplitude.
Click to expand...

In my case the amplitude is always varying.This is not the case of may and may not in my simulations.

To me due to Doppler, the channel is varying and hence the amplitude of the received signal is varying.

The Clarke's model also specifies that there will be a large component of the Doppler frequency in the received signal.
 

Does Doppler effect change the amplitude?
Click to expand...
Doppler effect no, fading generator yes.

Basic doppler effect involves a time-variant phase shift and no amplitude variation.
But the said fading generator (I don't know the specific MATLAB implementation) superimposes multiple channels.
 

Hi

FvM said:
Doppler effect no, fading generator yes.
Click to expand...

When I simulate the channel with zero Doppler I do not get a Sinusoidal component in the waveform but as I insert some Doppler then I get significant sinusoidal component in the waveform.
So Doppler is changing the amplitude in this case.
To me it is due to change in channel and different multipath components when arrive with different and time varying phase, we get a change in amplitude.
 

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