Adaptive lattice predictive filter

1. A method comprising:

decorrelating a sensor signal using a lattice filter to generate orthogonal backward prediction errors; and

estimating a disturbance correction signal using the orthogonal backward prediction errors.

2. The method of claim 1 , further comprising generating the sensor signal from a disturbance signal.

3. The method of claim 1 , further comprising using the disturbance correction signal to generate a storage device control signal.

4. The method of claim 3 , wherein the storage device control signal is a servo control signal for a disc drive.

5. The method of claim 1 , further comprising generating a phase normalized sensor signal based on the sensor signal, wherein decorrelating the sensor signal comprises decorrelating the phase normalized sensor signal.

6. The method of claim 1 , wherein decorrelating a sensor signal using a lattice filter comprises decorrelating a sensor signal using at least two lattice filters.

7. The method of claim 1 , wherein the sensor signal is generated from a disturbance signal of a storage device.

8. The method of claim 7 , wherein the storage device is a disc drive.

9. The method of claim 1 , wherein decorrelating a sensor signal further comprises generating a forward predictor error signal.

10. The method of claim 9 , further comprising:

generating a mean square error (MSE) of the forward prediction error signal and the orthogonal backward prediction error;

comparing the MSE to a threshold; and

if the MSE is above the threshold, further decorrelating the backward prediction errors.

11. The method of claim 1 , wherein the estimating step includes using a multiple regression filter to estimate the disturbance correction signal.

12. The method of claim 11 , wherein the generated orthogonal backward prediction errors are weighted before being inputted to a stage of the multiple regression filter.

13. The method of claim 1 , wherein the lattice filter includes multiple stages, the method further comprising:

evaluating a lattice stage error from at least one of the multiple lattice filter stages to determine if an additional lattice filter stage is to be added.

14. A circuit comprising:

a sensor circuit that generates a sensor signal from a disturbance signal;

a phase-normalization filter that normalizes the phase of the sensor signal;

a lattice filter circuit that decorrelates the phase-normalized sensor signal to generate orthogonal backward prediction errors; and

a multiple regression filter that estimates a disturbance correction signal using the orthogonal backward prediction errors.

15. The circuit of claim 14 wherein the disturbance signal is an external disturbance signal from a storage device and wherein the disturbance correction signal is input to an actuator of the storage device.

16. The circuit of claim 14 wherein the sensor circuit generates a sensor signal from a disturbance signal generated by a chassis of a data storage device.

17. The circuit of claim 14 , further comprising:

a comparator module adapted to generate a position error signal (PES) based on a reference position and a head position signal;

a servo control module adapted to generate a servo signal based on the PES;

a combination module adapted to combine the servo signal with the disturbance correction signal to generate a combined control signal; and

an actuator module adapted to generate an actuator signal to control an actuator arm of a disc drive using the combined control signal.

18. A servo control circuit, comprising:

a sensor circuit that generates a sensor signal from a disturbance signal related to a device;

a lattice predictor circuit comprising a plurality of lattice stages, wherein the lattice predictor circuit receives the sensor signal as an input and each stage of the plurality of lattice stages generates a backward prediction error;

a multiple regression filter comprising a plurality of regression stages, wherein the backward prediction error output from each stage of the plurality of lattice stages is input to a corresponding stage of the plurality of regression stages, and wherein the multiple regression filter generates a disturbance correction signal;

a combination module adapted to combine a servo signal with the disturbance correction signal to generate a combine control signal; and

an actuator module adapted to generate an actuator signal to control an actuator arm of a disc drive in response to the combined control signal.