Hello PY YEN,

Thank you for considering to use Texas Instruments.  The TX value depends upon the signal provided to CLKIN and your clock divider setting. Component Y1 which is part number ASEMB-8.000MHZ-LY-T provides 8MHz to the TDC1000.  The division factor of the clock divider can be programmed with the TX_FREQ_DIV field in the CONFIG_0 register.  There are some obstacles to measuring taller water levels than what is shown in the EVM user guide, but it might be possible for your application.  TIDA-00322 might be good starting place for figuring out how.

Hello PY YEN,

Thanks for posting to the sensors forum! The circuit suggested for TIDA-00322 is optimized for 1MHz performance but should work fine for 2MHz operation as well. You can alter the values in the bandpass filter if you are not getting the appropriate signal at the COMPIN pin, but change should not be necessary since the filter is speced for up to 3MHz. There are no expected changes for the high voltage driving circuit as well.

My recommendation would be to create this design in order to test this setup on your own tank. There can be some differences in performance depending on the tanks material so it is always good to try and use the same or similar tank you will use for your final application. The 2MHz transducer will provide a finer resolution for your measurements but please note that the higher the frequency the faster the signals attenuate since they cannot carry much energy. My recommendation to achieve a 1.5m distance is to incorporate a wave guide under the transducer. This helps keep the signal of the transducer concentrated and prevent it from spreading to maximize the detectable distance. This also  helps for instances if the tank is tilted and the wave guide also acts as a natural filter to improve signal to noise ratio.

If you need a starting point you can use the TDC1000-C2000EVM and simply create the boost circuit for testing. I hope this helps!

Best,

Isaac

Hello PY YEN,

No worries, always glad to help out!

We don’t have a part number for the waveguide, the waveguide is essentially an addition to the inside of the tank that fills along with the tank. Typically it can be made out of plastic. 

It just needs to at least be the diameter of the selected transducer to allow the entire signal from the transducer to enter the waveguide and have holes at the bottom or along its length to ensure that liquid fills it along with the tank.

The measurement is performed as normal, the waveguide just ensures increased stability and performance.

Best,

Isaac

Hello PY YEN, 

Let me help address your questions:

  1. With the optimized and suitable circuit on the same water tank , how about the propagation distance  of  1MHz & 2 MHz sensor  ?   will 2MHz sensor propagate further than 1MHz sensor ??   

• It is difficult to define the sensing range of each system since they can depend on many factors such as, how the transducer is being mounted, the tank material, frequency and driving voltage along with others. This is why we typically recommend testing on as close of a system to your final product as possible. A 2MHz transducer will have a lesser propagation distance than a 1MHz transducer, meaning the 1MHz transducer would be able to travel farther than the 2MHz transducer.

  2. If the sensor is enclosed with different material such as  metal  cover or  plastic cover   ,  will it affect the  propagation distance ? Will metal cover propagate further than plastic one ( while using the  same frequency sensor ) ?

•    Relating cover material with sensing range is not something we have really experimented with before. Typically, sensors with a cover are less sensitive compared to transducers that do not have covers. The benefit of covered transducers is that they are very robust for harsh environments.

I hope this helps!

Best,

Isaac

Hello PY YEN,

Glad to help out.

I dont have a direct example myself, but I am aware that customers have been able to achieve larger distances than what was tested using the TIDA-00322 solution in our documentation. They achieved this by increasing the voltage being generated by the transducer in order to have enough sound pressure to have enough strength to reach the end of their tank and return back to the sensor, the only thing I am not sure of is the exact distance they were able to achieve. 

Best,

Isaac

Hello PY YEN,

Thanks for the info. Like I said its hard to define a distance because its dependent on a lot of factors like tank material/thickness, voltage on the transducer, transducer fov, and so on. 

Have you tried using the waveguide in your tests to see if this helps you achieve a greater distance?

I would also suggest perhaps looking at TUSS4470, this device has an improved dynamic range compared to the TDC1000. Perhaps this will help you increase the sensing range. The device can be used in a similar way to the TDC1000, the TUSS4470 can generate an interrupt when the echo generates a signal high enough to trigger a programmed threshold, similar to the TDC1000. Unfortunately, the TUSS4470 only goes up to 1MHz excitation for transducers and is not automotive qualified if that is a requirement for your application.

Best,

Isaac 

Hello PY YEN,

The waveguide should improve your performance due to the fact that it keeps your ultrasonic signals energy from dispersing all over the tank. As far as the TUSS4470 goes, the same disclaimer goes as the previous solution its hard to quantify due to all the other factors, but the nice part about TUSS4470 is that you shouldn't require a separate circuit to drive the transducer at a higher voltage. This device can handle up to 36V without additional components, and the dynamic range is much larger, supporting up to 90dB of gain compared to the 32dB given by the TDC1000. So overall its a better device and should see some improvements in your setup.

Best,

Isaac 

Hello PY YEN,

No worries glad to help out. Please let me know if there is any other help needed. Feel free to start a new post regarding TUSS4470 if the questions are regarding that device in specific it helps users find answers much easier if  have if they have a similar question.

Best,

Isaac

Hello PY YEN, 

That is correct the TUSS4470 is the optimized solution for long distance measurements using a 1MHz transducer.

Best,

Isaac