Effective filter with small tap size
It is quite very difficult to give a correct answer, because you do not give the full information. But I will try.
One of standard way is using "matching filter":

http://en.wikipedia.org/wiki/Matched_filter

http://www.dspguide.com/ch17/3.htm

If length of your signal pattern is quite small (&lt;50 usec) you can use this method.