Sequential tracking and offline demodulation in receiver

1. A receiver for tracking and data demodulation comprising:

a baseband mixer having an output for providing I/Q data;

a sequential tracking unit to sequentially track a desired signal with a variable integration time, the sequential tracking unit comprising

an integrator having an input coupled to the output of the baseband mixer to receive the I/Q data, the integrator using a variable integration time;

a peak processor coupled to the integrator; and

a controller coupled to the peak processor to provide an adjustment signal; and

an automatic frequency control (AFC) loop to perform automatic frequency control of the desired signal, the AFC loop comprising

a data input coupled to the output of the baseband mixer to receive the I/Q data;

a control input coupled to the controller to receive the adjustment signal; and

a data demodulation unit to demodulate the desired signal.

2. The receiver of claim 1 , wherein the sequential tracking unit estimates a searcher frequency delta and inputs the searcher frequency delta to the AFC loop.

3. The receiver of claim 2 , wherein:

the receiver includes a global navigation satellite systems (GNSS) receiver; and

the desired signal is from a satellite.

4. The receiver of claim 1 , wherein the AFC loop uses offline software for performing automatic frequency control of the desired signal.

5. The receiver of claim 1 , wherein the data demodulation unit demodulates over an operating range of the desired signal.

6. The receiver of claim 1 , wherein the sequential tracking unit uses variable bandwidths.

7. The receiver of claim 1 , wherein the AFC loop is deactivated and realigned if a False Lock is detected.

8. The receiver of claim 7 , wherein the False Lock is detected by the AFC loop.

9. The receiver of claim 1 , wherein the sequential tracking unit includes a searcher center frequency, and wherein the sequential tracking unit estimates an estimated frequency of the desired signal.

10. The receiver of claim 9 , wherein the sequential tracking unit predicts a predicted frequency of the desired signal based on the estimated frequency.

11. The receiver of claim 10 , wherein the sequential tracking unit estimates a current searcher frequency delta based on a difference between the predicted frequency and the searcher center frequency.

12. The receiver of claim 11 , wherein the searcher frequency delta is used to correct a coherent I/Q sum.

13. The receiver of claim 12 , wherein:

the receiver includes a global navigation satellite systems (GNSS) receiver; and

the desired signal is from a satellite.

14. A receiver for tracking and data demodulation comprising:

means for mixing a signal to provide I/Q data;

means for sequentially tracking a desired signal with a variable integration time, the act of sequentially tracking comprising

means for integrating the I/Q data to form integrated data;

means for detecting a peak of the integrated data; and

means for controlling an adjustment signal;

means for performing automatic frequency control of the desired signal based on the adjustment signal; and

means for demodulating the desired signal.

15. The receiver of claim 14 , wherein the means for performing automatic frequency control includes means for deactivating and realigning if a False Lock is detected.

16. A method by a receiver for tracking a desired signal comprising:

mixing a signal to provide I/Q data;

sequentially tracking the desired signal with a variable integration time, the act of sequentially tracking comprising

integrating the I/Q data to form integrated data;

detecting a peak of the integrated data; and

controlling an adjustment signal;

performing automatic frequency control of the desired signal based on the adjustment signal; and

demodulating the desired signal.

17. The method of claim 16 , wherein the desired signal is from a GPS satellite.

18. The method of claim 16 , wherein:

the act of sequentially tracking includes estimating a searcher frequency delta; and

the act of performing automatic frequency control includes using the searcher frequency delta.

19. The method of claim 16 , wherein the act of sequentially tracking includes searching over range and Doppler dimensions.

20. The method of claim 16 , further comprising:

receiving a received signal; and

acquiring the desired signal from the received signal;

wherein the source of the received signal is from a Satellite Positioning System (SPS) source that is used for advanced forward link trilateration (AFLT).

21. The method of claim 16 , further comprising:

receiving a received signal; and

acquiring the desired signal from the received signal;

wherein the source of the received signal is from a terrestrial source that is used for advanced forward link trilateration (AFLT).

22. The method of claim 16 , wherein the act of demodulating includes demodulating over an operating range of the desired signal.

23. The method of claim 16 , wherein the act of sequentially tracking includes using variable bandwidths.

24. The method of claim 16 , wherein the act of performing automatic frequency control includes deactivating and realigning if a False Lock is detected.

25. The method of claim 24 , wherein the act of performing automatic frequency control includes detecting the False Lock.

26. The method of claim 16 , wherein the act of sequentially tracking includes:

using a searcher center frequency; and

estimating an estimated frequency of the desired signal.

27. The method of claim 26 , wherein the act of sequentially tracking further includes predicting a predicted frequency of the desired signal based on the estimated frequency.

28. The method of claim 27 , wherein the act of sequentially tracking further includes estimating a searcher frequency delta based on a difference between the predicted frequency and the searcher center frequency.

29. The method of claim 28 , further comprising using the searcher frequency delta to correct a coherent I/Q sum.

30. A non-transitory computer-readable medium including program code stored thereon, comprising:

program code to sequentially tracking a desired signal with a variable integration time, the act of sequentially tracking comprising

program code to integrate I/Q data to form integrated data;

program code to detect a peak of the integrated data; and

program code to control an adjustment signal;

program code to perform automatic frequency control of the desired signal based on the adjustment signal; and

program code to demodulate the desired signal.

31. The computer-readable medium of claim 30 , further comprising program code to estimate a searcher frequency delta and to input the searcher frequency delta for performing automatic frequency control.

32. The computer-readable medium of claim 31 , wherein the desired signal is from a GPS satellite.