| 摘要 |
PURPOSE:To obtain the automatic frequency controller which is suitable for IC-implementation by detecting a unique word(UW) before demodulating a received RF signal. CONSTITUTION:An extractor 3 extracts a UW corresponding part from the intermediate frequency(IF) signal of the output of an A/D converter 2. A correlation calculating means 41 performs mutual correlation processing with modulated waveforms generated by modulating three kinds of frequencies, i.e., a frequency f1 as high as a desired intermediate frequency signal, a little higher frequency f1, and a little lower frequency f2 with the UW. A comparing decision means 42 determines which of f0, f1, and f2 have a maximum correlation value. An integrating means 43 averages the output of the comparing decision means 42 and increases or decreases the counted value of a counting means 44 according to the mean value. A D/A converter 6 converts the counted value from digital to analog and outputs the result to a voltage-controlled oscillator(VCO) 7. The VCO 7 outputs a local oscillation frequency corresponding to the output of the D/A converter 6. |
