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PGA460-Q1: Fishfinder using PGA460-Q1

Part Number: PGA460-Q1
Other Parts Discussed in Thread: PGA460, TDC1000

Dear Friends.

Now I am going to develop a wireless FishFinder using PGA460-Q1.

I found most commercial wireless Fishfinders have used dual frequencies 50KHz for long range and 200KHz for shorter range.

My fishfinder will have maximum depth range 50m and I have not yet decided which protocol to use for wireless.

I see PGA460-Q1 is mainly for automotive applications.

I am wondering if it is possible  to develop fishfinder using this chip.

If so, could you recommend which transducer is suitable for my project.

Thanks for any reply.

  • Chai,
    The PGA460 is intended for air-coupled ultrasonic applications, so we have no data to confirm whether or not our device can support water-coupled applications. However, our device does support the frequency range you've listed (50kHz to 200kHz), so you are more than welcome to make an attempt. I do not know of many water coupled transducers, although Prowave appears to have the 200LM450 "Underwater Ultrasonic Transducer" with a center frequency of 200kHZ.
    Other potential closed-top transducer candidates/vendors include: Audiowell, Massa, Murata, PUI Audio, SensComp, and SensorTec.
  • Dear Akeem.

    Thanks for your view and nice reply.

    Yes. I am willing to go further.

    But I have one more question.

    What seems to be the most challenge to this chip for underwater application?

    And what is the difference to air-coupled ultrasonic applications?

    Thanks again and best regards.

  • Chai,

    The rate of ultrasonic attenuation increases as the medium becomes denser. Air, being less dense than water, allows low-frequency ultrasound to travel farther, when compared to using the same ultrasonic frequency in water. Ultrasound attenuation in air increases as a function of frequency and humidity. Therefore, air coupled ultrasound is typically limited to frequencies below 500kHz due to excessive path loss/absorption.

    The speed of sound is also impacted by the transmission medium. To put it in perspective, sound travels nearly five times faster in water (1481m/s) than through air (343m/s), which also impacts the rate of ultrasonic attenuation. For this reason, high-frequency ultrasound, usually in the hundreds+ kHz range, is more suitable for liquid transmission. Therefore, TI's PGA460-Q1 is recommended for air-coupled applications (supports up to 480kHz), while TI's TDC1000 can be paired with frequencies operating at higher frequencies.

    For more information on the fundamentals of ultrasound, I recommend that you visit:
    www.nde-ed.org/.../cc_ut_index.htm
  • Thanks again for your time.
    To be honest, I had development in Sonar Development.
    So I have basic understanding of underwater acoustic.
    But as I wrote, my fishfinder will use ultrasound of 200KHz which PGA460-Q1 supports.
    What I am asking is what will be the main challenge if I use this chip for underwater applications like Fishfinder.
    Thanks for understanding and best regards.
  • Chai,
    Given our team's lack of experience/testing in using the PGA460-Q1 in water-coupled applications, I am unable to comment on the feasibility or potential challenges of using the 200kHz transducer underwater.

    I would be interested to see the outcome of your testing if you decide to use the PGA460-Q1 for your testing.
  • Akeem.

    Thanks again for your time and reply.

    Certainly I will go to test and let you know the result.

    In the datasheet,  it is written like Record Time for Object Detection up to 11 m.

    Does this indicates time record limit measurable in air?

    If so, because of what this limit exsit?

    As we know, the speed of sound is five times faster in the water than in the air.

    It means we can detect object up to 55m depth in the water?

    Thanks again.

  • Hello Chai,

    You are correct. The PGA460 record time can be set up to 65ms, but maximum distance is dependent on the transmission medium.

    • The speed of sound through air is approximately 343 m/s; therefore, the maximum detectable distance is 11m.
    • The speed of sound through water is approximately 1,484 m/s; therefore, the maximum detectable distance is 48m.

    The PGA460 Frequently Asked Questions (FAQ) and EVM Troubleshooting Guide (http://www.ti.com/lit/pdf/slaa733) contains FAQ #5.1 How can I detect an object if it is further than 11m? if extended ranging is necessary.

  • PGA460 is good. But I would recommend you to go for Deeper Smart Sonar its really great and a portable fish finder. Although I do agree that with the distance increase you will lose the signal strength and face connectivity issues. But that is what associated with all kind of wireless fish finders. But still your decision is not bad and is a good decision.