PGA460: Recommendation for Transducer selection&frequency

Hello Stephan,

Thanks for the patience on this let me help address your questions:

1. transducer type /Vendor/part number (shall be a closed transducer as it needs to work in a quite humid environment as it is placed above the water
   1. We have a list of transducers we have tested on our website, the list is not limited to these so feel free to test other transducers. If you order the EVM it comes with a transducer out of the box so it could be a good place to start. Please follow this link to view this list: www.ti.com/.../slac787
2. 1 transducer (for send&receive or 2 transducers?
   1. We refer to this as mono-static or bi-static topologies. This mainly depends on the distances you are trying to measure and the frequency of your transducer. If you are trying to make really small measurements 2 transducers may be necessary but higher frequency transducers attenuate faster. If your minimum requirement is 3cm I would lean towards using 2 transducers. 
3. transducer frequency?
   1. If the measurement is traveling through water we typically recommend using a high frequency to have a better resolution since the speed of sound is faster. If its coupled through air and just reflecting off the top of the water then you will not need such a high frequency. You can calculate resolution using this formula: Resolution = (1/frequency)*speed of sound
4. what is the maximum cable length from driver output to the transducer sender (and from transducer receiver to input if bistatic configuration is recommended)
   1. This mainly depends on the transducer itself, we usually recommend performing these tests on your system or asking the transducer manufacturer for more info.

Please review this document as I believe it has a lot of information that may help you along the design process: https://www.ti.com/lit/an/slaa732a/slaa732a.pdf

I hope this helps please let me know if there are any other questions!

Best,

Isaac