| 摘要 |
First and second oscillation frequencies are supplied from first and second PLL synthesizers (1,2). First, the first oscillation frequency is increased by a predetermined frequency amount corresponding to the change-over of channels, and is instantly decreased to the original frequency, while the second oscillation frequency is increased at a time behind the increase of the first oscillation frequency without the decrease thereof to the original frequency by the predetermined frequency amount, such that the lowest level in the vibration of the first oscillation signal is coincident at timing to the highest level of the second oscillation signal. The first and second oscillation signals thus controlled are combined in a mixer (3) to provide an output oscillation signal. Therefore, lock time to a new frequency is reduced and the system gain is high. <IMAGE> |
