| 摘要 |
In a channel selecting apparatus for a television receiver having a tuner with a voltage-controlled, variablereactance device as its tuning element, and in which such tuning element has a non-linear relation between its control voltage and the resulting receiving frequency; a sweep pulse generator is operable for producing sweep pulses, a counter counts the sweep pulses for producing progressively changing binary codes corresponding to the changing counts of the counter and which represent respective control voltages for the variable reactance device, a digital-to-analog converter receives the binary codes and converts the same into the respective control voltages for the variable reactance device, and a circuit is provided for varying the period of the sweep pulses so that the rate of change of the receiving frequency is substantially uniform over the range of the progressively changing binary codes. Such circuit for varying the period of the sweep pulses is preferably operable by the binary codes so as to respond to the changes in the latter.
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