Did anyone know the ofdm PN correlation process? Why the output value of PN-Peak is very small?

Hi guys,

Thanks in advance .

I am doing the ofdm preamble sync test, using the pn-peak PN Correlation
Please refer to* ofdm_sync_pn.py* file.

Before the normalization process, I open the
gr__peak_detector_fb.ccfile, and try the print out the peak_val, to
see if the peak_value is very
large. According the PN correlation process, I believe the peak value is
subjected to ifft_length, at least 64 or more. But the actual output
is very small, nearly 2 or 3. I am so confused.
*The PN correlation method can be referred to T. M. Schmidl and D. C.
“Robust Frequency and Timing Synchonization for OFDM,” IEEE Trans.
Communications, vol. 45,no. 12, 1997.