This sets the LNB's receive local oscillator frequency in MHz, which combines with the received satellite frequency to derive the modem's actual receive frequency, with 0 disabling the feature. Getting this right matters because the demodulator tunes based on the resulting Terminal Frequency = LNB_LO plus or minus Rx_Frequency, so an incorrect LO here means the modem is listening on the wrong satellite frequency even if its own Rx setting is correct. With a 10750 MHz LO and low-side mix, a satellite downlink at 11700 MHz would appear to the modem's demodulator as 950 MHz.