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IWR6843AOPEVM: Noise level and direction

Peter Bramsen
Prodigy 110 points
Part Number: IWR6843AOPEVM

I'm currently looking at an application where I'm interested in the values that are primarily filtered out currently as noise.

I'm able to track the over all noise level using the mmWave demo and it's responding as the mathematical theory predicts it should in response to the specific characteristics i'm looking at so that's a good start. However, i'm wondering if it's possible to get more detail. so my question is multi part.

1. I want to evaluate a cloud of moving particles at a fairly close range. In any given second there may be thousands or 10's of thousands of particles in the field of view. I can see the impact these particles have as a surge in the noise level but how much data is actually being received for the noise and how is the sum noise level calculated? 

2. Do the "noise" signals have recorded direction and strength?

3. Does the DCA1000 board allow for the recording and parsing of individual returned signals, whether they are seen as noise or object?

4. Is there a practical limit to the maximum number of signals that can be processed per chirp? I'm not sure how many signals I need to process per chirp but the more the better. 

5. Can the radar be set up to just observe particles at Z distance away from the transceiver and X-X distance to the right or left? I.E. flat horizontal plane extending out from the transceiver and to ignore anything that is above or below the normal plane relative extending perpendicular from the face plane of the transceiver? I just want to get a horizontal slice through my particle field. 

I want to be able to just look at the noise and completely ignore any non-moving, stationary objects.

  • 0
    TI__Mastermind 32905 points

    HI, there:

    Any object that reflect radar signal is a target and not noise.  The cloud of particles in your description should be considered as target not noise.  Noise is usually means thermal noise level in our terminology.   In the received chain, all the reflections coming from your clouds of particles will be part of the received signal.  They will be processed together.  

    Again, the received signal is the sum of all the reflections, but based on the particle distance and particle moving speed, you will be able to separate some during the signal processing.   The traditional signal processing is 2D FFT, range FFT + Doppler FFT, the output can be used to generate range-Doppler heatmap.  IF you have thousand of particles move randomly, you probably will see a energy cloud in the range-Doppler heatmap.  

    Since we have multiple TX and multiple RX antenna, the signal cross different antenna tell you the target direction, you can do further signal processing to check the energy in angle domain.    After you calculate both range and angle information, you can focus on your desired range and angle plane.  You can also design your antenna to have a narrow elevation FOV (field of view) to focus on the flat horizontal plane.  

    Please go through the FMCW training to understand the fundamentals of our radar. https://training.ti.com/intro-mmwave-sensing-fmcw-radars-module-1-range-estimation?context=1128486-1139153-1128542

    Best,

    Zigang

     

  • 0 in reply to zigang Yang
    Prodigy 110 points

    It doesn't appear to be behaving as "thermal noise" since it's an instantaneous jump on the range/noise graph and the temperature readout doesn't change. the Noise level also immediately disappears when I disable eliminate the particles. 

  • 0 in reply to Peter Bramsen
    TI__Mastermind 32905 points

    Hi, Peter:

    If the particles are moving, then you will see energy moves on the range-Doppler heat-map.  The energy comes and goes are reflected energy from your particles.   When you nothing moving in front of the radar, then the energy level on the non-zero Doppler bins are usually thermal noise.   

    Best,

    Zigang

  • 0 in reply to zigang Yang
    TI__Mastermind 32905 points

    HI, Peter:

    Since I did not see any feedback, I am closing this e2e thread for now.  

    Best,

    Zigang