| 摘要 |
Displacement between two signals on a record media is precisely measured by counting the number of capstan tachometer signals occurring between the two signals. This count is time metered per tachometer cycle to calculate an average velocity. In addition, elapsed times between immediately adjacent tachometer signal changes and the signals are measured. The average velocity per tachometer cycle is then multiplied by the total number of tachometer cycles and those portions of a tachometer cycle occurring adjacent the signals. With the known distance per tachometer cycle, the total elapsed time is a precise indication of the distance between the two signals. This method is also used for measuring media slip. Upon occurrence of a first signal, the media is stopped. After stopping, the media is started, all the while measuring the distance the media is moved. Distance measured at a constant velocity is then compared with the latter measurement to indicate slip.
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