Pre-amble detection techniques

Hello

Enjoying reading all about the USRP (and other SDR) and gnu radio

Anybody got some advice on pre-amble detection techniques ?

Sliding window ?

fifo ?

Looking for some Mode S signals. 0.5 us pulses, located at 0us, 1us,
3.5us and 4.5 us.

------T----T---------T-----T-------------------

Andrew