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Radar sensor Forum Discussions

shoko_s
Level 4
Level 4
25 sign-ins 25 replies posted 10 sign-ins

Hello, 

I have measured Range of target using Radar Fusion GUI. 

Peak near 0Hz often appears in Range spectrum. (Please see the following image. )

1.png

Please let me know what caused the peak near 0Hz. 

There is not any target besides 1.7m target. 

Please advise. 

Thank you.  Shoko  

 

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1 Solution
HoneyDhandhukia
Moderator
Moderator
Moderator
25 likes received First comment on blog First question asked

Hello @shoko_s ,

The reflection from the PCB board comes from the coupling between transmitter and receiver antenna, you can apply high pass filter to lower down the amplitude at particular range/frequency. But as the effect is from hardware side, it will be difficult to remove or cancel it

Best Regards,
Honey

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HoneyDhandhukia
Moderator
Moderator
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25 likes received First comment on blog First question asked

Hello @shoko_s ,

Please refer to the below image as an explanation for the graph:

Peak_om.PNG

Hope this helps!

Best Regards,
Honey

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shoko_s
Level 4
Level 4
25 sign-ins 25 replies posted 10 sign-ins

Hello Honey, 

I read the explanation of the above image but I can't understand. I think that it is not explained for "Peak near 0Hz". 

The peak near 0Hz is DC component? phase noise? from Mixer. 

Please let me know what the peak near 0Hz does come from? 

If you don't understand what I said, could you change the person in charge? 

Please advise. 

Regards, Shoko 

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HoneyDhandhukia
Moderator
Moderator
Moderator
25 likes received First comment on blog First question asked

Hello @shoko_s ,

The peak near 0 Hz/0m seems to be DC component, please make sure the DC REMOVAL option is selected as shown in the figure below, while working with sensor.

peak_om_1.PNG

Furthermore, the peak seems the effect of some board /package reflection.Since, for the range plot there is no static target removal option available. So, we would suggest you apply MTI Filtering for your own application for the same. 


BR,
Honey

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shoko_s
Level 4
Level 4
25 sign-ins 25 replies posted 10 sign-ins

Hello Honey, 

Thank you for your response. 

Regarding the peak near 0 Hz/0m, please let me know the mechanism by which it is generated by board / package reflection.

Please advise.

Best regards, Shoko

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HoneyDhandhukia
Moderator
Moderator
Moderator
25 likes received First comment on blog First question asked

Hello @shoko_s ,

Yes, the peak seems to be the effect of reflection of some board/package or some nearby object, please make sure the test environment is clean of any possible false targets.

BR,
Honey

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shoko_s
Level 4
Level 4
25 sign-ins 25 replies posted 10 sign-ins

Thanks Honey, 

Why does reflection cause a peak near 0Hz?

Please let me know the calculation formula. 

Thanks and regards, Shoko 

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HoneyDhandhukia
Moderator
Moderator
Moderator
25 likes received First comment on blog First question asked

Hello @shoko_s ,

A single target in front of the radar produces an IF signal that is a constant frequency tone, the frequency being given as shown in the figure below.

reflection_1.PNG

This constant frequency tone can be visualized by performing a Fast Fourier Transform (FFT) on the IF signal and then extracting the magnitude spectrum. A plot of magnitude spectrum across range values is called as a Range FFT Plot. If there are multiple targets in front of the radar, the magnitude spectrum of the IF signal will reveal multiple tones, the frequency of each being proportional to the range of the target from the radar. In other words, the location of the peaks directly correspond to the range of the targets. 

Since the radar can detect both static and moving target and addition to that, if there are any more reflections from the environment they are also seen as clutter during the signal processing. The range spectrum in Fusion GUI represents the raw data from each antenna, which may also include some reflections from false target or even the board. To rectify the effect, the Moving Target Indicator (MTI) method can be implemented as it helps to discriminate moving targets from static targets and clutter. Please refer to the figure below for detailed explanation. 

MTI.PNG

You may also refer to the SDK Documentation and Fusion GUI help content for further explanation

Hope this helps!

Best Regards,
Honey

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shoko_s
Level 4
Level 4
25 sign-ins 25 replies posted 10 sign-ins

Hello Honey, 

Thanks for your reply. I already know the principle of Range FFT. 

"The location of the peaks directly correspond to the range of the targets. "

You mean, the  peak near 0Hz is the reflection from the PCB board? 

I would like to know where in the PCB board the reflection occurs for example. 

Please advise. 

Best regards,    Shoko 

 

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HoneyDhandhukia
Moderator
Moderator
Moderator
25 likes received First comment on blog First question asked

Hello @shoko_s ,

The reflection from the PCB board comes from the coupling between transmitter and receiver antenna, you can apply high pass filter to lower down the amplitude at particular range/frequency. But as the effect is from hardware side, it will be difficult to remove or cancel it

Best Regards,
Honey

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shoko_s
Level 4
Level 4
25 sign-ins 25 replies posted 10 sign-ins

Hello Honey, 

Thanks for your help. 

I understand where in the PCB board the reflection occurs. 

Thank you and best regards, Shoko 

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