I need a clean 40Mhz square wave to power the "sender" transducer
I don't need huge resolution on my reading (I think 8-bits would be plenty)
no ultrasonic transducer can respond to a frequency that high.
I thought that maybe I could achieve this with ultrasound transducers, by looking at the travel time from a sender to a receiver. The idea is really straightforward, but the catch is that I would need to be sampling a 40kHz sine wave at a minimum of 3MHz for the resolution required.
How do you account for amplitude changing with distance?