| 摘要 |
PURPOSE:To attain easy tuning operation by changing the tuning sweep time in response to a frequency so that the relation between a tuning voltage and a tuning sweep time at a frequency sweep band is linear thereby making the change in the array display constant independently of the value of a reception frequency. CONSTITUTION:An output signal of a reference signal oscillator 9 is given to an up-down counter 8 as a clock signal, and a means 12 frequency-dividing the clock signal with a prescribed ratio and a switch 13 switching the clock signal into the clock signal as it is and a frequency-divided clock signal are inserted between them. A frequency dividing ratio signal of the counter 8 is inputted to a programmable frequency divider 5 and a subtractor 14, the subtractor 14 operates a difference N-Nx between the output frequency dividing ratio N and the frequency dividing ratio Nx corresponding to a prescribed reference frequency, outputs a carry signal with N-Nx<0, sets the switch 13 to the position of a terminal 1 and drives the counter 8 at the normal speed. Further, the switch 13 is thrown to the position of a terminal 2 at N-Nx>=0 so as to drive the counter 8 at a speed lower than the normal speed. |
