| 摘要 |
PROBLEM TO BE SOLVED: To obtain a carrier frequency correctly. SOLUTION: An intermediate frequency digital QPSK signal is given to a conversion section 21, in which the signal is converted into a complex base band signal based on a base frequency ω of the QPSK signal, the base band signal is biquadrated at a calculation section 24, the result of biquadration is given to a FFT circuit 25, a frequency at which a peak is obtained in the FFT result is divided into 1/4 at a frequency divider 26, the obtained error frequency Δω and the frequency ω are added to obtain a carrier frequency of an input signal. |
