| 摘要 |
PURPOSE:To obtain a center frequency accurately by quantizing the input signal to 3-value levels in the thresholds provided vertically symmetrically with respect to the center level in a measuring method for narrow band irregular signals utilizing correlations. CONSTITUTION:Thresholds V(+) and V(-) are provided vertically symmetrically with respect to the center level of an input signal. A level discriminating circuit 1 produces a positive output when the input signal exceeds the threshold V(+) and zero output in other case, and a level discriminating circuit 1' produces a negative output when the input signal is below the threshold V(-) and zero output in other case. The outputs of the circuits 1, 1' are inputted to delay circuits 2, 2', by which they are delayed by the same time. The outputs of the circuits 1, 1' and 2, 2' are mutually ANDed by an AND circuit 3, after which they are integrated in an integrating circuit 4. Said integrated output is positive when the above-mentioned delay times are large and negative when small. Said output is so controlled as to be made zero, whereby the center frequency of the input signal is obtained. |
