| 摘要 |
PURPOSE:To realize a demodulation having a reduced distortion in a wide band with elimination of the specified relation between fC and fS, by counting the number of the zero-crosses of the input sample value FM signal and then counting the reciprocal number in the time interval during which the number of the zero-crosses reaches a certain set value to carry out an FM demodulation. CONSTITUTION:The means 5 is provided to count the number (l) of the zero- crosses in which either one of the two consecutive sampled values e(kT) and e[(k- 1)T] is positive and the other is negative respectively for the FM signal e(kT) (k:an integer) of the carrier frequency fC that is sampled in the sampling period T. Then in case when (k) is defined as (i) with l=1 obtained by the means 5 and (k) is defined as (j) in the case of l=N(N: >=2 integer), (d) is obtaned which is expressed as d=e(iT) / [e(iT)-e[(j-1)T]]+(j-1-i)+e[(j-1)T]/[e[(j- 1)T]-e(jT)]. Then the arithmetic means 6 and 7 are provided to calculate (N- 1)pi/d-2pifCT. |
