IR puls modulation problem

Any1 know how you measure the puls on an IR range detector, when using a modulation?

How do i know where on the puls the A/D converter, convert the DC puls. As the voltage will fluxtate from 0V-5V, so how do i make sure the A/D convertion happens every time on the top of the puls?

IRS are analog.

unless you have a digital pulse IR sensor, it won’t pulse for a Looooong time.

If you do, then 58 ms = 1 cm.