초록 ▼

An interference signal from an adjacent signal is prevented and a desired signal demodulated. A frequency conversion circuit 4 converts a received signal frequency to a first intermediate frequency signal of a first intermediate frequency higher than the frequency of the signal to be demodulated by

An interference signal from an adjacent signal is prevented and a desired signal demodulated. A frequency conversion circuit 4 converts a received signal frequency to a first intermediate frequency signal of a first intermediate frequency higher than the frequency of the signal to be demodulated by 57 MHz. The first intermediate frequency signal is further converted to a second intermediate frequency signal of a second intermediate frequency by a frequency conversion circuit 8. The second intermediate frequency is a frequency lower than the 57 MHz of the first intermediate frequency by exactly a frequency 쩍 of an FFT sampling f-clock. A clock generation circuit 11 generates a signal of a frequency two times the FFT sampling clock, that is, four times the second intermediate frequency. The second intermediate frequency is sampled by the A/D conversion circuit 10 based on the signal supplied from the clock generation circuit 11, demodulated by a demodulation circuit 12, and subjected to an FFT operation by an FFT circuit 13, whereby the signal is demodulated.

대표청구항 ▼

The invention claimed is: 1. A receiving apparatus comprising: a first converting means for converting a received signal to a first intermediate frequency signal by using a signal of a first frequency; an extracting means for extracting a signal of a predetermined bandwidth from the first intermedi

The invention claimed is: 1. A receiving apparatus comprising: a first converting means for converting a received signal to a first intermediate frequency signal by using a signal of a first frequency; an extracting means for extracting a signal of a predetermined bandwidth from the first intermediate frequency signal; a second converting means for converting the signal output from the extracting means to a second intermediate frequency signal by using a signal having a frequency lower than the first frequency by exactly a frequency 쩍 of an FFT (fast Fourier transform) sampling frequency; and a demodulating means for digitally demodulating the second intermediate frequency signal based on a clock of a frequency two times the FFT sampling frequency, wherein an oscillation frequency and a frequency forming an image are calculated from a channel selected by a user and a band forming an image frequency is suppressed in advance. 2. The receiving apparatus as claimed in claim 1, wherein a bandwidth which said extracting means extracts has said first frequency as a center frequency and is equal to a bandwidth of one segment of the received signal. 3. A receiving method comprising: a first conversion step of converting a received signal to a first intermediate frequency signal by using a signal of a first frequency; an extraction step of extracting a signal of a predetermined bandwidth from the first intermediate frequency signal; a second conversion step of converting a signal output at the extraction step to a second intermediate frequency signal by using a signal having a frequency lower than the first frequency by exactly a frequency 쩍 of an FFT sampling frequency; a demodulation step of digitally demodulating the second intermediate frequency signal based on a clock of a frequency two times the FFT sampling frequency; calculating an oscillation frequency and a frequency forming an image from a channel selected by a user; and suppressing a band forming an image frequency. 4. A computer-readable medium adapted to store a computer program for making a receiving apparatus execute processing, the computer program comprising: program code for converting a received signal to a first intermediate frequency signal by using a signal of a first frequency; program code for extracting a signal of a predetermined bandwidth from the first intermediate frequency signal; program code for converting a signal output at the extraction step to a second intermediate frequency signal by using a signal having a frequency lower than the first frequency by exactly a frequency 쩍 of an FFT sampling frequency; program code for digitally demodulating the second intermediate frequency signal based on a clock of a frequency two times the FFT sampling frequency; program code for calculating an oscillation frequency and a frequency forming an image from a channel selected by a user; and program code for suppressing a band forming an image frequency. 5. A receiving apparatus comprising: a converting means for converting a received signal to an intermediate frequency signal by using a signal having a frequency higher than the frequency of the received signal by exactly a frequency 쩍 of an FFT sampling frequency; and a demodulating means for digitally demodulating the intermediate frequency signal based on a clock of a frequency two times the FFT sampling frequency; wherein an oscillation frequency and a frequency forming an image are calculated from a channel selected by a user and a band forming an image frequency is suppressed in advance. 6. A receiving method comprising: a conversion step of converting a received signal to an intermediate frequency signal by using a signal having a frequency higher than the frequency of the received signal by exactly a frequency 쩍 of an FFT sampling frequency; a demodulation step of digitally demodulating the intermediate frequency signal based on a clock of a frequency two times the FFT sampling frequency; calculating an oscillation frequency and a frequency forming an image from a channel selected by a user; and suppressing a band forming an image frequency. 7. A computer-readable medium adapted to store a computer program for making a receiving apparatus execute processing, the computer program comprising: program code for converting a received signal to an intermediate frequency signal by using a signal having a frequency higher than the frequency of the received signal by exactly a frequency 쩍 of an FFT sampling frequency; program code for digitally demodulating the intermediate frequency signal based on a clock of a frequency two times the FFT sampling frequency; program code for calculating an oscillation frequency and a frequency forming an image from a channel selected by a user; and program code for suppressing a band forming an image frequency.