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Linux/IWR1443BOOST: Change chirp configuration (.cfg file) using ROS

William James8
Prodigy 40 points
Part Number: IWR1443BOOST
Other Parts Discussed in Thread: IWR1443, IWR1642BOOST

Tool/software: Linux

Hello,

I've been trying to upload different chirp configurations to the IWR1443 mmWave sensor and plot the resulting Point Cloud using ROS. The already given example runs perfectly. However, I've tried to run it giving as an input a different .cfg (instead of 1443_2d/3d.cfg) file and I doesn't work (I've taken the .cfg files from the TI mmWave chirp database). In general, tends to give different errors while sending the configuration parameters to the sensor - and specially with the last  "sensorStart" of the .cfg file-.  Is there any limitation in terms of what chirp configurations can work jointly with ROS or anything I consider when trying to use different .cfg files? 

Thanks!

  • 0
    TI__Mastermind 30405 points

    Hi William,

    Please follow the instructions provided under the section named Reconfiguring the chirp profile in the ROS point cloud visualizer user's guide to generate a new config using the mmWave Demo Visualizer and apply it to the ROS demo per the provided instructions. The chirp configurations provided in the Chirp database may not be compatible with the mmWave SDK OOB demo (which is what the ROS driver uses on the EVM) as mentioned in the Testing and Results section of the corresponding Chirp. The ones which can work with the OOB Demo and hence the ROS Point Clloud Visualizer have it clearly mentioned in this section. For  instance, the Very Fine Motion Detection Chirp states the following:

    Testing and Results

    The chirp configuration files provided above were tested with the corresponding EVMs (IWR443BOOST and IWR1642BOOST) using the out of box demo and mmWave Demo Visualizer. The motion was detected on the X-Y Scatter and Doppler-Range plots on the mmWave Demo Visualizer. Please refer to the Very Fine Motion Detection experiment for details of the Test Setup and Results.

    Please mark the thread as resolved if this answered your question otherwise let us know if you need more support on this topic.

    Thanks

    -Nitin

  • 0 in reply to Nitin Sakhuja
    Prodigy 40 points

    Hi Nitin,

    Thanks for your answer, was very helpful. Also in a related manner, while using the mmWave Demo Visualizer, is there any way to know the range accuracy any chirp configuration? That value is given for the chirp configurations database but I couldn't find it while using the demo visualizer.

    Thanks,
    William

  • 0 in reply to William James8
    TI__Mastermind 30405 points

    Hi William,

    Please note that the accuracy specified in most of the chirps in Chirp database is the the theoretical maximum accuracy which is a function of Range resolution and SNR. It is defined as Range Accuracy = Range Resolution / Sqrt (2 x SNR). Make sure to convert the SNR to linear scale (10^(SNRdb/10). before using in this equation. Additional post processing may be needed in software to achieve this value.

    The achievable accuracy also depends upon (limited by) the size of the FFT as it defines the FFT resolution (aka range inter-bin resolution). Intuitively, the FFT granularity needs to be fine enough to measure the desired range increment. Sso the application may need to first get an initial coarse range measurement using the provided chirp configuration and then perform a zoom FFT on the range of interest, using additional processing in software with a higher order FFT. This technique is demonstrated in the High Accuracy Range measurement Labs available in the mmWave Industrial toolbox. 

    The mmWave Demo Visualizer does not provide the (theoretical) range accuracy for the chirp configuration but you can calculate it using the formula provided above.

    Regards

    -Nitin

  • 0 in reply to Nitin Sakhuja
    Prodigy 40 points

    Hi Nitin,

    Thanks again for your help. However, your answer has lead me to another doubt. My goal is detecting an object (drone) with the smallest accuracy and highest range possible. In that case, there would not be other object around, therefore the resolution wouldn't be important (although as you mentioned on your previous answer, resolution and accuracy relate to each other through SNR.) I have two questions I hoped you could assist me with:

    1- I'd like to be able to have a range vs accuracy characterization. I've figured that the best way to do so would be that for any given distance, I calculate the SNR, and with it, the accuracy. This should show that from d=0 to d=dmax, the accuracy keeps decreasing. Is there any way I could have that kind of characterization for the IWR1443. I've noticed that while using the demo visualizer, resolution and maximum range relate to each other whereas they do not in theory (I assume that not every chirp config is possible and the pair B-Tmeas changes with it). Also, which would be fair values for RCS, Tmeas, SNRmin while calculating dmax on the following formula?

    2- As I mentioned before, I'm interested in measuring a certain object with the highest accuracy and farthest range (no velocity estimation needed). Although this relates to the previous one, is there any particular configuration on the Demo Visualizer you'd recommend me for that experiment? This also related to the Tmeas value from the previous question.

    To sum up, what would be the right configuration in order to detect a drone and how could I characterize the distance-accuracy pair.

    Thanks a lot!

    William

  • 0 in reply to William James8
    TI__Mastermind 30405 points

    Hi William,

    We don't have a range vs accuracy characterization but you can make one for a particular Range Resolution and SNR yourself.

    1. Even though range resolution may not be important in your application, higher range resolution is needed for higher accuracy.

    2. Now range resolution translates into Bandwidth so effectively you need to fix the bandwidth and SNR and then plot the accuracy vs Range resolution (i.e. bandwidth) and accuracy vs SNR plots.

    I would recommend you to enter your application requirements such as max range, range resolution (keep it as fine as possible until you see errors in Sensing estimator due to IF bandwidth and/or Memory limitations), max velocity and velocity resolution into mmWave Sensing Estimator and derive a chirp configuration. Sensing estimator take the above Radar Equation and also the device specific considerations into account to generate the right sensor parameters for the use case.

    Regards

    -Nitin