Ultrasonic ink Level circuit

I want to make a circuit that can convert the low, high, empty,overflow analog signals
from an ultrasonic pickup into digital signals eg 1 for True condition. I have never purchased such sensor form the market. The distance is maximum 20cm for empty level. It should be small in size. Please help with the possible design consideration, circuit, catalog website etc.

What sort of signal does it output?

If it's just a votlage then it sounds like a comparator will do.

ultrasonic sensors generate analog signal proportional to the level. These produce acoustic sound waves above 20KHZ. The intensity of reflected waves decide the level.
That is a rough idea, regarding these sensors.

A simple comparator should work.