I've not understood really well your question but, when I used the srf04 (something similar), I remember It was pretty easy.
You get an impulse with the lenght proportional to the first reflection.
Be careful when you send the second impulse, it should be when the various previous reflections are estinguished.

I've not understood your question very well but, when I used the srf04 (something similar), I remember it was pretty easy.

You get an impulse with the length proportional to the first reflection. Be careful when you send the second impulse, it should be when the various previous reflections are extinguished.