| 摘要 |
The receiver has a memory for the alternative frequencies of the adjusted transmitter and a circuit for altering the tuning of the receiver to an alternative frequency. At least one of two separate oscillators (10,11), whose frequencies and levels can be mutually independently adjusted, can be set to an alternative frequency. A changeover switch (7) is used to selectively connect one of the two oscillators to the mixing stage (3). The oscillators are controlled by phase-locked-loops or PLLs. A second changeover switch synchronised with the first connects the output of the PLL loop filter of the oscillator to be switched in with the control input of a selective intermediate circuit. |
