Granted Patent B1

US 7,272,369 · App. 11/115,784 · Granted Sep 18, 2007

Abstract

Claims (67)

1. A method of performing a frequency correction of a radio module, said method comprising:

determining a first estimated frequency error for said radio module;

applying a first frequency correction to said radio module based on said first estimated frequency error;

if said first estimated frequency error is greater than a first pre-determined amount, determining a second estimated frequency error for said radio module after said applying said first frequency correction; and

if said second estimated frequency error is within a second pre-determined amount, applying a second frequency correction to said radio module based on said second estimated frequency error.

2. A method as described in claim 1 further comprising:

if said second estimated frequency error is not within said second pre-determined amount, restoring an original reference frequency.

3. A method as described in claim 1 further comprising:

determining if said radio transceiver receives data validly after said second frequency correction;

if said data is valid, updating a reference frequency based on said first and second estimated frequency errors; and

if said data is not valid, restoring an original reference frequency.

4. A method as described in claim 1 further comprising:

if said first estimated frequency error is less than or equal to said first pre-determined amount, updating a net total of all frequency errors since the last time a reference frequency stored in memory was updated; and

if said net total is greater than a third pre-determined amount, storing in memory a new reference frequency based on said net total and the previous reference frequency stored in memory.

5. A method as described in claim 1 wherein said determining a first estimated frequency error comprises:

sampling frequency data a plurality of times during a quiescent period; and

applying a median filter to said frequency data.

6. A method as described in claim 1 wherein said second pre-determined amount comprises a frequency value.

7. A method as described in claim 1 wherein said second pre-determined amount comprises a pre-determined percent of said first frequency error.

8. A method of performing a frequency correction of a radio module, said method comprising:

determining a first estimated frequency error for said radio module using an original reference frequency;

if said first frequency error is larger than a pre-determined value, executing a large shift frequency correction by:

modifying said original reference frequency based on said first estimated frequency error;

determining if said first frequency correction is satisfactory;

if said first frequency correction is not satisfactory, restoring said original reference frequency; and

if said first frequency correction is satisfactory, further modifying said original reference frequency based on said determining if said first frequency correction is satisfactory;

if said first frequency error is smaller than a pre-determined value, executing a small shift frequency correction.

9. A method as recited in claim 8 wherein said executing said small shift frequency correction comprises:

modifying said original reference frequency based on said first estimated frequency error;

updating a net total of all frequency errors since the last time a reference frequency stored in memory was updated; and

if said net total is greater than a pre-determined amount, storing a new reference frequency based on said net total and the previous stored reference frequency.

10. A method as recited in claim 9 , wherein said determining if said first frequency correction is satisfactory comprises:

determining a second frequency error for said radio module; and

determining if said second frequency error is satisfactory.

11. A method as recited in claim 10 , further comprising:

determining if said radio transceiver receives data validly after said further modifying said original reference frequency;

if said data is valid, storing said reference frequency as modified by said first and second frequency errors; and

if said data is not valid, restoring said original reference frequency.

12. The method as recited of claim 11 further comprising following said restoring said original reference frequency by correcting said original reference frequency by performing a binary search for a suitable reference frequency.

13. The method as recited of claim 11 further comprising following said restoring said original reference frequency by correcting said original reference frequency by performing a step-by-step search for a suitable reference frequency.

14. A communications device, said device comprising:

a radio module that is tunable using a reference frequency;

logic operable to:

determine a first estimated frequency error for said radio module;

modify said reference frequency based on said first estimated frequency error;

if said modification to said reference frequency is greater than a first pre-determined amount, determine a second estimated frequency error after said modifying said reference frequency; and

if said second estimated frequency error is within a second pre-determined amount, further modify said reference frequency based on said second estimated frequency error.

15. A communications device as described in claim 14 wherein said logic is further operable to:

if said second estimated frequency error is not within said second pre-determined amount, restore said reference frequency.

16. A communications device as described in claim 14 wherein said logic is further operable to:

determine if said radio transceiver receives data validly after said further modifying said reference frequency;

if said data is valid, store for future reference said reference frequency as modified by said first and second estimated frequency errors; and

if said data is not valid, restore said reference frequency.

17. A communications device as described in claim 14 wherein said logic is further operable to:

if said modification to said reference frequency is less than or equal to said first pre-determined amount, update a net total of all frequency errors since the last time a reference frequency stored in memory was updated; and

if said net total is greater than a third pre-determined amount, store in memory a new reference frequency based on said net total and the previous reference frequency stored in memory.

18. A communications device as described in claim 14 wherein said determining a first estimated frequency error comprises:

sampling frequency data a plurality of times during a quiescent period; and

applying a median filter to said frequency data.

19. A communications device as described in claim 14 wherein said second pre-determined amount comprises a frequency value.

20. A communications device as described in claim 14 wherein said second pre-determined amount comprises a pre-determined percent of said first estimated frequency error.

21. A communication device as described in claim 14 further comprising:

a display for displaying information.

22. A communication device as described in claim 14 further comprising:

a user-interface operable to allow a user to interact with said communications device.

23. A communication device as described in claim 14 further comprising:

a memory operable to store information.

Assignments (7)