Thanks for your reply. I still have one question. I try to plot the peak detection data to observe the the shape of the peak, which seems like a plateau(square wave).I have done a simulation before in matlab. If only one preamble exist, when the 1st half of the preamble correlate with 2nd half, the shape of peak should be much sharper(like a triangle), because the repeated pattern is not enough.
My question is :
If gunradio only use one preamble with 2 repeated pattern, the shape of the peak should look like a triangle rather than a plateau, is that right?