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  • TI Thinks Resolved

CCS/IWR1642: IWR1642

Prodigy 190 points

Replies: 8

Views: 137

Part Number: IWR1642

Tool/software: Code Composer Studio

What is TI IWR1642's 77Ghz FMCW advantage over same Bandwidth UWB?

Since there are so many UWB radar available recently, we would like to know why (how much in which quality)we should go with TI 1642 solution?

Specially we are interested in project "Vital Sign". Several UWB radar baord offers vital sign measuring distance over 8 meter. What can be the good reason for FMCW TI solution over UWB module?

  • Hello,

    1) Fundamentally at mmWave frequencies such as 77GHz/60GHz wavelengths are smaller this helps in getting the Antenna size smaller and hence over all smaller solution leading to smaller board size and lower cost of over all system.

    2) Better range resolution : With 4 GHz continuous Bandwidth gives better range resolution

    3) If you compare with the Pulse radars UWB radars, FMCW radar offers lower IF frequency band, hence lower sampling rates leading to simpler ADC and signal processing chain. This enables low power architecture based Radar system.

    4) Rich point cloud, better velocity resolutions are better.

    You could review below application note for getting higher level understanding advantages working with mmWave sensing as compared to UWB.
    www.ti.com/.../spry328.pdf
  • In reply to CHETHAN KUMAR Y.B.:

    1) Fundamentally at mmWave frequencies such as 77GHz/60GHz wavelengths are smaller this helps in getting the Antenna size smaller and hence over all smaller solution leading to smaller board size and lower cost of over all system. 

    [kisub] According to your comment, comparing to 24Ghz UWB, it would be about 3 times smaller with the same accuracy. Right?


    2) Better range resolution : With 4 GHz continuous Bandwidth gives better range resolution

    [kisub] FMCW 4Ghz vs UWB 250Mhz. Therefore, it should be 16 times better in terms of range resolution. For example, UWB 100 meter coverage vs FMCW 400 meter coverage.

    3) If you compare with the Pulse radars UWB radars, FMCW radar offers lower IF frequency band, hence lower sampling rates leading to simpler ADC and signal processing chain. This enables low power architecture based Radar system. 

    [kisub] Lower IF frequency band > Simpler ADC, Signal Processing Chain. Accordingly Low power. 

    4) Rich point cloud, better velocity resolutions are better.
    [kisub] Even though TI FMCW offer more rich point cloud and support only 1 meter distance measurement, Several UWB radar baords offer vital sign measuring distance over 8 meter.  What would be the reason for the longer distance measurement?


    You could review below application note for getting higher level understanding advantages working with mmWave sensing as compared to UWB.
    www.ti.com/.../spry328.pdf

  • In reply to CHETHAN KUMAR Y.B.:

    1) Fundamentally at mmWave frequencies such as 77GHz/60GHz wavelengths are smaller this helps in getting the Antenna size smaller and hence over all smaller solution leading to smaller board size and lower cost of over all system.

    [kisub] According to your comment, comparing to 24Ghz UWB, it would be about 3 times smaller with the same accuracy. Right?


    2) Better range resolution : With 4 GHz continuous Bandwidth gives better range resolution

    [kisub] FMCW 4Ghz vs UWB 250Mhz. Therefore, it should be 16 times better in terms of range resolution. For example, UWB 100 meter coverage vs FMCW 400 meter coverage.

    3) If you compare with the Pulse radars UWB radars, FMCW radar offers lower IF frequency band, hence lower sampling rates leading to simpler ADC and signal processing chain. This enables low power architecture based Radar system.

    [kisub] Lower IF frequency band > Simpler ADC, Signal Processing Chain. Accordingly Low power.

    4) Rich point cloud, better velocity resolutions are better.
    [kisub] Even though TI FMCW offer more rich point cloud and support only 1 meter distance measurement, Several UWB radar baords offer vital sign measuring distance over 8 meter. What would be the reason for the longer distance measurement?
  • In reply to kisub Jung:

    Hello Kisub,

    Please find my comments below:

    1) Fundamentally at mmWave frequencies such as 77GHz/60GHz wavelengths are smaller this helps in getting the Antenna size smaller and hence over all smaller solution leading to smaller board size and lower cost of over all system.

    [kisub] According to your comment, comparing to 24Ghz UWB, it would be about 3 times smaller with the same accuracy. Right?

    [Chethan] Right,  You could refer to below webinar foils to understand better.

    https://training.ti.com/sites/default/files/docs/Mmwave_webinar_Dec2017.pdf

    2) Better range resolution : With 4 GHz continuous Bandwidth gives better range resolution

    [kisub] FMCW 4Ghz vs UWB 250Mhz. Therefore, it should be 16 times better in terms of range resolution. For example, UWB 100 meter coverage vs FMCW 400 meter coverage.

    [Chethan] Range resolution is a function of the available bandwidth from the radar signal 4GHz Bandwidth offers 3.75cm range resolution as compared to 60 cm in case of 24GHz-250Mhz Bandwidth radar.  Range resolution is important in Industrial systems to reliably identify and separate closely spaced objects, and it will not help in achieving larger distance.  To achieve larger distance other elements of radar system need to be tweaked such as output power,  Antenna gain, memory with coherent integration, lower  noise figure of the receiver system etc...

    3) If you compare with the Pulse radars UWB radars, FMCW radar offers lower IF frequency band, hence lower sampling rates leading to simpler ADC and signal processing chain. This enables low power architecture based Radar system.

    [kisub] Lower IF frequency band > Simpler ADC, Signal Processing Chain. Accordingly Low power.

    [Chethan] Absolutely, your comments are right. and Lower memory requirement as well.

    4) Rich point cloud, better velocity resolutions are better.

    [kisub] Even though TI FMCW offer more rich point cloud and support only 1 meter distance measurement, Several UWB radar baords offer vital sign measuring distance over 8 meter. What would be the reason for the longer distance measurement?

    [Chethan] Vital sign measurement requires higher SNR for better performance of the application.  Larger the distance SNR would reduce and there could be increase in the false detection.  Hence to get the best accuracy of the demo  demo is range gated to 1 meter distance.

    However you could change the configuration as shown below in the user-guide.  

    Thanks and regards,

    CHETHAN KUMAR Y.B.

  • In reply to CHETHAN KUMAR Y.B.:

    I tried to change vitalSignsCfg Start and End Range (0.3 , 1,0) to Start and End Range (2.5 , 3). and ran for a while such as 5 minutes. But, it could not detect me.

    What else can I do?

  • In reply to kisub Jung:

    Kisub,

    Assuming that you are using the default chirp configuration that is included in the vital signs demo, the effective maximum range of the provided chirp is approximately 7 meters. So specifying a start and end range of 2.5 to 3 meters should work successfully in the vital signs lab. Please make sure that you are sitting directly in front of the sensor when you are attempting to take these measurements. You might also need to adjust the scaling factors that are used in the vitalSignsCfg CLI command.

    Regards,
    Kyle
  • In reply to Kyle Cousino:

    I would like to have two more questions according to your answer.

    1. I would like to measure vital sign as high accurately as I can in the room 5X5X2.5(height) [0 to 5 meter range]. To do it, what would be better approach for this specification? In my opinion, I can increase accuracy by tracking person and get angle and range and monitor area around that range bin. Any suggestion?

    2. How can I get higher accuracy for vital sign only? I think I can get higher accuracy by increasing FFT to 4K FFT. What do you think? 

  • In reply to kisub Jung:

    Kisub,

    In order to achieve the best vital sign measurements, the sensor needs to be placed at a chest height to the person that you are trying to measure vital signs. We have not tested vital signs measurement when placing the sensor high up in a large room as you describe in your question.

    With regards to your second question, there will not be a noticeable difference in accuracy if you increase to a 4K FFT. The heart waveform and breathing waveform are extrapolated using an IIR and two different band pass filters.

    Regards,
    Kyle

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