Patent ID: 7856066

Claim:
An OFDM receiver comprising: a tuner which receives a radiofrequency signal subjected to orthogonal frequency division multiplex modulation therein and converts the same to an intermediate frequency signal; a variable gain amplifier which amplifies the intermediate frequency signal in accordance with a gain control signal; an analog-digital converter which converts the signal amplified by the variable gain amplifier to a digital signal; a fast Fourier transformer which transforms the digital signal into signals in a frequency domain corresponding to a plurality of carriers; an equalizer which processes the signals outputted from the fast Fourier transformer in accordance with a Doppler detection signal thereby to make synchronization between the carriers so as to produce received data; a level control circuit which generates a control signal corresponding to the gain control signal, for bringing an average level of the digital signal to a predetermined level, based on the digital signal; a digital-analog converter which analog-converts the control signal to produce the gain control signal; and a Doppler frequency detector which extracts frequency components of the control signal thereby to produce the Doppler detection signal.