| 摘要 |
A method and system for receiving a signal in a received frequency and shifting the received frequency to become a desired frequency is provided. The system includes a controllable oscillator for generating a first internal frequency, a frequency estimating unit connected to the controllable oscillator, a first frequency shift unit, connected to the controllable oscillator and to the frequency estimating unit, for shifting the received frequency according to the first internal frequency, thereby obtaining an initially shifted frequency and a second frequency shift unit connected to the first frequency shift unit and the frequency estimating unit for shifting the initially shifted frequency. The frequency estimating unit determines a total frequency shift value from the desired frequency, the received frequency and the first internal frequency and it also determines a first frequency shift value and a second frequency shift value from the total frequency shift value. Furthermore, the frequency estimating unit provides a first frequency change command to the controllable oscillator, so as to correct the first internal frequency according to the first frequency shift value, a second frequency change command to the second frequency shift unit, so as to shift the initially shifted frequency according to the second frequency shift value.
|
