Patent ID: 7251300

Claim:
A method of frequency tracking for an automatic frequency control (AFC) subsystem, the method comprising: (a) correlating a recovered data with a received data to produce a first correlated data; (b) delaying said first correlated data of step (a) to produce a delayed first correlated data; (c) correlating said first correlated data of step (a) and said delayed first correlated data of step (b) to produce a second correlated data; (d) adding an imaginary part of said second correlated data to said second correlated data of step (c) to produce a decision data indicative of the frequency fluctuation of said received data; (e) increasing a positive register if said decision data is greater than 0; (f) increasing a negative register if said decision data is less than 0; (g) repeating steps (a)-(f) for N iterations; (h) tuning a voltage controlled oscillator that is associated with said AFC by one frequency step in a negative direction if said positive register is greater than a predetermined threshold value; and (i) tuning said voltage controlled oscillator that is associated with said AFC by one frequency step in a positive direction if said negative register is greater than said predetermined threshold value.