| 摘要 |
A variable rate tuner is one in which the rate of change of tuned frequency with respect to tuning shaft rotation varies automatically as a function of the shaft rotation speed. In this tuner the circuitry is completely digital, including a shaft encoder which puts out shaft velocity and shaft direction signals. A digital multiplier multiplies or divides the shaft velocity signal. A counter selects the multiplication factor as a function of shaft velocity. The multiplied velocity signal then increments or decrements a frequency-determining quantity, depending upon whether the shaft direction is such as to increase or decrease the tuned frequency.
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