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IWR1443: mmWave Radar Sensors: Object Versus Range

user6356280
Intellectual 315 points
Part Number: IWR1443

There are two points that are unclear in the document below, could you please let me know?

mmWave Radar Sensors: Object Versus Range (Rev. A) (ti.com)

1. This is true for all graphs, but why is the reception strength of about 60 dB occurring even in locations where there is no target object?

    Is it because noise is superimposed? What causes the noise?

2. This is true for all graphs, but why is there a peak around 0-10m?

    

Best Regards,

  • 0
    TI__Mastermind 34560 points

    Hi,

    user6356280 said:

    1. This is true for all graphs, but why is the reception strength of about 60 dB occurring even in locations where there is no target object?

    This scale is relative, so that 60 dB is not really meaningful. It just means 60 dB above an arbitrary noise floor.

    user6356280 said:

    2. This is true for all graphs, but why is there a peak around 0-10m?

    This may be due to near-field effects, antenna coupling, or reflections from the ground.

    Best,

    Nate

  • 0 in reply to Nathan Block
    Intellectual 315 points

    Thank you for your answer.

    Please tell me additional information about question 1.

    This may be a rudimentary question, but I would appreciate an answer.

    ・60 dB higher than the noise floor, but both the noise and range profiles on the graph appear to indicate about 60 dB. What exactly do you mean by 60 dB higher than the noise floor?

    ・What exactly does the noise profile indicate? Is it the received intensity during the time the transmitting antenna is not transmitting?

    Best Regards,

  • 0 in reply to user6356280
    TI__Genius 15320 points

    Hello.

    Nathan is out of office; please expect a delay in response.  Thank you for your patience.

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    TI__Mastermind 34560 points
    user6356280 said:

    ・60 dB higher than the noise floor, but both the noise and range profiles on the graph appear to indicate about 60 dB. What exactly do you mean by 60 dB higher than the noise floor?

    There is a minimum signal strength that corresponds to the LSB of the ADC in the signal chain of the radar. All this graph is saying is that the noise power measured is 60 dB above that LSB. When viewing this plot, I would recommend looking at the difference between the peak value and the noise floor, which appear to be about 80 dB and 60 dB respectively, for an SNR of 20 dB (which is quite a lot!).

    user6356280 said:

    ・What exactly does the noise profile indicate? Is it the received intensity during the time the transmitting antenna is not transmitting?

    See documentation here.

  • 0 in reply to Nathan Block
    Intellectual 315 points

    Thank you for your answer.

    Let me ask an additional question.

    I understand that the noise profile represents the noise in the receiver.

    I believe that if I can reduce this noise, I will be able to detect objects more easily because the difference between the peak value and the noise floor will be larger.

    What measures can be taken to reduce this noise?

    Best Regards,

  • 0 in reply to user6356280
    TI__Mastermind 34560 points

    Hi,

    You can add more chirps to increase the SNR, or decrease your sampling rate. When you decrease your sampling rate, you reduce the noise bandwidth. See the SNR equation here for some inspiration.

    https://www.ll.mit.edu/sites/default/files/outreach/doc/2018-07/lecture%202.pdf

    Best,

    Nate

  • 0 in reply to Nathan Block
    Intellectual 315 points

    Thank you for your answer.

    Thank you for sharing the material.

    If I have any questions, I will ask them in another thread.

    Thank you for your cooperation.

    Best Regards,