US Patent 7697644 Stepped automatic gain control for OFDM systems

A system and method for performing stepped automatic gain control (AGC) for orthogonal-frequency-division-multiplexing (OFDM) applications comprises a radio frequency (RF) tuner and an OFDM demodulator operatively connected to the RF tuner, the OFDM demodulator comprising logic circuitry adapted to (i) detect OFDM symbols from a stream of data; (ii) detect boundaries of the OFDM symbols; (iii) detect a cyclic prefix duration of data values associated with the OFDM symbols; and (iv) provide a feedback to the RF tuner of the information pertaining to the boundaries of the OFDM symbols and the cyclic prefix duration.