| 摘要 |
<p>Frequency and periodic time measurement of non-coherent wave packages in Dopple velocity meters uses counter and comparison logic. The time of single periods is measured by means of a counter and the reciprocal value is formed. The measurement is compared with store information. If the new measurement deviates from the last mean value, the comparison logic limits a signal via a control logic. In order to prevent erroneous measurements and to achieve initiation the number of zero passages of the input signal is registered by a "bad value" counter (7). The counter (7) is restored to zero by a "good measurement".</p> |
