How to shape a gaussian pulse to a clear square pulse?

[ferdem]

Hi all, I have 50Khz returning echo signal in an ultrasound application. Echo signal is amplified well but need to be reshaped. It is like gaussian pulse and I want to convert it to a clear square pulse. Here waveforms:
**broken link removed**

Now I m using envelope detector preceding a comparator, like an ASK demodulator. Results are not bad but I m looking for some other circuits that may have better performance, more suitable etc. I have a few opamps and passives. What would you suggest me? Thanks in advance.

 

[Einar M]

I worked on such a system 30 years ago. We used a limiting amp to flatten the wave shape before any pulse detection circuitry. Don't remember any more details.