OFDM Synchronization

Hi,

I am currently making a OFDM receiver in @ltera DSP builder...using 10
short preambles and 2 LP...so here is my question

1. when we detect the start of the packet using the short preamble....how
do we know as to whether its SP1 , sp2 ...or SPi.

2.because based on this, we have to start with the long preamble
detection.

i know the algorithm for sp packet detection and lp symbol sync ...but
dunno the timing relation between the end of packet detection and symbol
sync

pls help me out....its urgent !

thanks in advance