| 摘要 |
A variable rate tuning circuit of the type which may be used to control the frequency of transmitters, receivers, and transceivers includes a manually rotatable dial (15) connected to a pulse generator (20) the output of which produces pulses directly proportional to the amount of dial rotation. These pulses are applied directly to a frequency determining counter (10), and the pulse rate is such that fine resolution over the frequency of the device may be obtained directly from rotating the dial slowly. Large changes in frequency may be made by rotating the dial rapidly. The output pulses pass through a differentiator (40), and integrator (30) to a voltage-to-frequency converter (35). The faster the dial is rotated, the larger will be the analog voltage output of the integrator, thus the higher the output frequency of the converter (35). The output of the converter is also applied to the frequency determining counter (10). Therefore, the amount the counter is incremented or decremented with respect to the amount of dial rotation is a function of the speed at which the dial is rotated.
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