| 摘要 |
The modulated baseband signal which has a continuous useful signal and noise signal spectrum is first of all band-restricted with a bandpass filter and then sampled at a sampling frequency (fa) which lies below the minimum sampling frequency prescribed by the sampling theorem. The sampling frequency (fa) is not less than the double value of the difference between the upper and the lower stop band frequency of the band-restricted useful signal spectrum, and the useful signal spectrum lies within one period segment ((1)/2fa). This undersampling produces a sampling frequency (fa) of around 3000 Hz which allows the use of an 8-bit microcomputer as a digital filter in a ripple-control receiver. <IMAGE> |
