| 摘要 |
PURPOSE:To speed receiving operation by making a sweep speed higher fast feeding than in step feeding. CONSTITUTION:When an up switch 2 is closed within 500ms, a switch 4 is also closed and an FF10 is set, so that an output Q is at a lever H for 500ms from this point in time. Consequently, an output pulse is applied from a reference oscillator 1 to the up the up input of an up-down counter via an AND gate 11 to increase the frequency in steps of 100kHz. Then, the output is supplied to a PLL circuit 9, so the reception frequency is swept by only 100kHz. When the switch 2 is pushed continuously for >=500ms, the FF10 is inverted 500ms later, so AND gates 10 and 11 are closed while AND gates 13 and 14 are opened. Consequently, the output of an oscillator 1 is applied to the up-down counter 7 via the gate 13, so that the up- down counter 7 goes up in steps of 300kHz from the reception frequency, set by step feeding, as a preset value. |
