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BOOSTXL-PGA460: Dimension of Target

Shivam Saxena
Prodigy 20 points
Part Number: BOOSTXL-PGA460
Other Parts Discussed in Thread: PGA460

Hi, 

Just wanted to know that if there are any specifications on the dimensions of the TARGET  that is to be sensed?

Meaning if the sensor can sense up to a particular Distance for a definite shape/size.

Any suggestion on this is appreciated, 

Thanks.

  • 0
    TI__Mastermind 27950 points
    Hi Shivam,

    The target properties for ultrasonic sensing are based on a combination of acoustic impedance mismatch (material) and radar cross section (shape and size). Both of these concepts are discussed in detail in section 2 of the PGA460 Ultrasonic Module Hardware and Software Optimization app note at: www.ti.com/.../slaa732.pdf

    In short, a large flat highly dense material (e.g. steel sheet) will return a stronger echo than a narrow/rounded object (e.g. rope).
    In an opposite extreme, a large flat sheet of spongy absorbent material will return very little energy, while a narrow steel pole will reflect strongly.

    What type of target are you attempting to detect, and at what range? I may be able to give a feasibility review based on my experience.
  • 0 in reply to Akeem Whitehead
    Prodigy 20 points

    Hi Akeem,

    Thanks for your reply. 

    As for what you have asked:

    I am trying for Long Range detection i.e., approximately 6+ meters.

    Now for the “Type of Target”, that is what I am looking for.

    I think with the increase in distance, the Size (and Type) of Target will play an important role. I went through the document (slaa732.pdf) and videos but I’m not able to find any answer.

    Like you have mentioned, I might use the Steel sheet but what should be the (Approx.) minimum dimensions of that sheet so that I can get a good reflection at such a distance.

    The conditions are Practical so of course Noise will be there.

    Any Suggestions?

    Thank You.

  • 0 in reply to Shivam Saxena
    TI__Mastermind 27950 points
    Hi Shivam,

    You are correct, as distance increases, ultrasonic echo attenuation increases, and the size, shape, and material of the target become increasingly relevant. The slaa732.pdf document discusses these parameters as follows:
    • Size/Shape = Sonar Cross Section. In short, it is easier to detect an object that reflects energy back in the direction of the sensor. A wall returns more energy than a ball.
    • Material = Acoustic Impedance Mismatch refers to the amount of ultrasonic energy is absorbed by certain materials versus the amount that is reflected from the material. In short, soft/spongy material is more likely to absorb the echo than a solid/metal.

    In general, you should be able to detect most human sized objects up to 6+ meters.