Frequency adjustment method

1. A frequency adjustment method, applied to a reference oscillation signal, the method comprising:

dividing a frequency scan section into M scan frequencies, wherein M is a positive integer greater than 1;

down-converting a signal according to the M scan frequencies to obtain M down-converted signals;

performing a correlation calculation operation on the M down-converted signals, respectively, to obtain M correlation results;

grouping the M scan frequencies into N frequency groups, wherein N is a positive integer greater than 1, performing a group calculation operation on the N frequency groups, respectively, to obtain N group calculation results; and

selecting a target frequency group from the N frequency groups according to the N group calculation results, and obtaining an adjusted oscillation frequency from the target frequency group,

wherein each frequency group comprising P selected frequencies, wherein P is a positive integer greater than 1, corresponding to P consecutive scan frequencies in the frequency scan section, wherein every two consecutive frequency groups in the N frequency groups comprise same (P−1) selected frequencies,

wherein the step of performing the group calculation operation on the N frequency groups, respectively, to obtain the N group calculation results comprises:

selecting the frequency group on which the group calculation operation is to be performed from the N frequency groups;

selecting P correlation results from the M correlation results according to the target frequency group;

sequentially corresponding P weightings to the selected P correlation results, and performing a weighted accumulation operation on the selected P correlation results; and

repeating the above steps to obtain the N group calculation results corresponding to the N frequency groups.

2. The method according to claim 1 , wherein M is an odd number.

3. The method according to claim 1 , wherein M=N+(P−1), and P is greater than 2.

4. The method according to claim 1 , wherein the step of dividing the frequency scan section into the M scan frequencies divides the frequency scan section into the M scan frequencies according to a frequency scan step.

5. The method according to claim 1 , wherein the step of down-converting the signal according to the M scan frequencies to obtain the M down-converted signals comprises:

sequentially selecting one of the M scan frequencies according to a predetermined sequence and utilizing the selected scan frequency as a frequency of the reference oscillation signal; and

down-converting the signal by the reference oscillation signal to obtain the M down-converted received signals.

6. The method according to claim 5 , wherein the predetermined sequence is an incremental selection sequence, a decremental selection sequence or an interleaved selection sequence.

7. The method according to claim 1 , wherein the P correlation results are selected from the P selected frequencies in the target frequency group.

8. The method according to claim 1 , wherein the P weightings are determined according to a proportion function.

9. The method according to claim 1 , wherein the step of selecting the target frequency group from the N frequency groups according to the N group calculation results, and obtaining the adjusted oscillation frequency from the target frequency group comprises:

obtaining an extreme value according to a comparison on the N group calculation results;

selecting the frequency group having the extreme value to be the target frequency group; and

obtaining the adjusted oscillation frequency from the P selected frequencies in the target frequency group.

10. The method according to claim 9 , wherein the extreme value is a maximum value of the group calculation results.

11. The method according to claim 9 , wherein the step of obtaining the adjusted oscillation frequency from the P selected frequencies in the target frequency group obtains a central selected frequency according to the P selected frequencies and utilizing the central selected frequency as the adjusted oscillation frequency.

12. The method according to claim 11 , wherein:

when P is an odd number, the central selected frequency is the scan frequency corresponding to a ((P+1)/2) th selected frequency in the target frequency group; and

when P is an even number, the central selected frequency is an average of the scan frequencies corresponding to a (P/2) th selected frequency and a ((P+2)+1) th selected frequency.

13. The method according to claim 1 , wherein the step of down-converting the signal according to the M scan frequencies to obtain the M down-converted received signals comprises:

down-converting the signal according to an initial oscillation frequency to obtain an initial down-converted signal;

storing the initial down-converted signal; and

down-converting the initial down-converted signal according to M frequency differences between the scan frequencies and the initial oscillation frequency, respectively, to obtain the M down-converted received frequencies.

14. The method according to claim 13 , wherein the initial frequency is an ((M+1/2) th frequency scan section.

15. The method according to claim 13 , wherein the initial oscillation frequency is an average value of the frequency scan section.