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PGA450Q1EVM / how to increase detecting distance

K.Yaita
Guru 29710 points
Other Parts Discussed in Thread: PGA450Q1EVM

Hi Team,

Could you tell me the "evaluation tab setting" that can increase maximum detecting distance with PGA450Q1EVM?
I assume transducer-transformer sensor pair is default (using Murata MA58MF14-7N and Mitsumi K5-R4).

*current setting is the following.


Best Regards,
Yaita / Japan disty

  • 0
    TI__Mastermind 27940 points
    Hello K.Yaita,

    The Downsample register setting determines both the record length and resolution. TI offers a downsample rate between 25-to-50 (or 3.3m-to-6.6m, or 20ms-to-29ms). To maximize the detectable distance, set the downsample to 50 (for 50us intervals), and maximize the blanking timer to 255. Based on your snapshot, I advise to download the latest GUI from the PGA450Q1EVM product page.

    Here is an excel equations that can be used to convert required maximum distance to downsample equivalent:
    =ROUNDUP(([Distance]/(343/2))/768*(1000000),0)
  • 0 in reply to Akeem Whitehead
    Guru 29710 points

    Hi Akeem-san,

    Thank you for your support.

    I would like to confirm if the following equation comes from datasheet. (I coudn't find the equation in datasheet..)
    --------------------------------------------------------------
    Here is an excel equations that can be used to convert required maximum distance to downsample equivalent:
     =ROUNDUP(([Distance]/(343/2))/768*(1000000),0)
    --------------------------------------------------------------
    Best Regards,
    Yaita / Japan disty

  • 0 in reply to K.Yaita
    TI__Mastermind 27940 points
    Hi Yaita,

    The downsample minimum equation is given in the datasheet in section 8.2.2.2.2 Downsample Rate.

    The Excel equation and datasheet equation yield the same results. Here is how the variables of the two relate in the Excel format:
    [Distance]/(343/2) : solving for time = distance/velocity
    •Distance = distance in meters from transducer to target
    •343 = speed of sound in meters per second
    •2 = divider of two to split the round-trip time into one-way
    time/768*(1000000): solve for required downsample rate based on FIFO memory size and ADC output rate
    •768 = FIFO memory size of 768 8-bit cells
    •1000000 = ADC has a sample rate of 1MSPS
    Rounding up since downsample register value must be whole.