Fc_in_MHz input defined in openofdm_rx.v but not listed anywhere else as a source

in the latest version openofdm_rx.v has Fc_in_MHz defined as a 16 bit input and that is used in the syn long and phase estimation. 

But i dont see any where where this is connected.

What does Fc_in_MHz refer to as a 16bit value?

Is it center frequency? if so the IQ data is already at baseband. Or do we set this to 0?
