| 摘要 |
PURPOSE:To improve C/N to obtain a flat phase characteristic and to reproduce the carrier of a high-speed modulated signal by adding a moving average circuit and taking the moving average of carrier components to slowly limit the band of carrier components. CONSTITUTION:An input modulated signal (a) is distributed to an inverse modulator (carrier component extracting circuit) 12 through an orthogonal detector 10 and a delay line 11. The inverse modulator 12 extracts a carrier component (a) and inputs it to a moving average circuit 13 which is operated at the clock speed of a frequency (f) corresponding to a signal (a). The circuit 13 converts it to a carrier component c2 obtained by taking the moving average for n clocks, and this component c2 is inputted to a latch circuit 14. The circuit 14 thins this component at the clock speed of f/n to obtain a carrier component c3, and this component c3 is inputted to a digital filter 15 operated at the clock speed of f/nHz. Thus, the digital filter constituting a carrier reproducing filter is operated at the low-speed clock signal, and high C/N and the flat phase characteristic are obtained. |
