Patent ID: 7751487

Claim:
A radio communication apparatus which uses a low-intermediate frequency to receive a multiband OFDM signal for hopping a center frequency at a specified band interval, said apparatus comprising: frequency conversion means for converting the received multiband OFDM signal into a low-intermediate frequency signal; an intermediate frequency filter to remove unnecessary waves in a low-intermediate frequency signal frequency-converted by said frequency conversion means, the intermediate frequency filter including a Hilbert bandpass filter formed by two real filters having a same characteristic and interconnected by a gyrator, a predetermined absolute value being used for a half-band frequency of a ladder-type low-pass filter as a real filter, the predetermined absolute value also being used as a center frequency of said Hilbert bandpass filter, and an integer ratio being used for an element value of a ladder-type prototype filter; AD conversion means for AD converting a filtered low-intermediate frequency signal output by the intermediate frequency filter into a digital signal using a specified sampling frequency to induce frequency folding in the digital signal; and OFDM demodulation means for demodulating the digital signal into a sequence of sub-carriers along a frequency axis so as to perform fast spectrum analysis, wherein said OFDM demodulation means sorts, after demodulation, the sequence of sub-carriers changed due to the frequency folding caused by the specified sampling frequency during AD conversion.