This app note is for a PSOC1, I am just going through the details now.
I'm wondering how it might change if a PSOC3/5LP were used instead. I don't see anything obvious that could be further "optimized"? the signal pre-conditioning is still needed as far as i can see.
I was wondering if the same signal pre-conditioning is requored if instead of using a comparator instead it was brought in through the PGA and ADC and Digital filter? The application being looked at may be slightly more interested in the analog response back from the ultrasonics.
First link to a PSOC 4 solution, the other a circuit cellar solution -