| 摘要 |
The invention relates to a method and an apparatus for accurate digital determination of the time or phase position of a signal pulse train in relation to a fixed time or frequency reference. The arrangement generates and produces directly on the output a digital word corresponding to the measuring value current at that time. The pulse train is compared in a plurality of EXCLUSIVE-OR gates (OR0-OR3) with a number of reference clock signals (RCL0-RCL3) which are mutually displaced in time. There is produced on the output of each gate a signal (MS0-MS3) which is dependent on the input signals of the gates with respect to frequency and pulse ratio. The output signals from the gates are sent to a comparison circuit (CO) in which a MIN of MAX operation is carried out, the pulse ratio of the output signals (MS0-MS3) being compared and the output signal which lies nearest to a predetermined pulse-ratio value being subjected to analogue/digital conversion in a converter (AD). The pulse train, in digital form, is thereafter code-converted in a code converter (CC) together with the three most significant bits taken from the pulse train prior to the AD-conversion process. The thus produced binary code can be corrected for systematic deviations resulting from frequency differences between the frequency, reference frequency and/or sampling frequency of the pulse train, by the addition/subtraction of a predetermined numeric sequence. |
