Motion detection for tracking

1. A method for tracking a target associated with a motion detection unit and a mobile tracking unit, the method comprising:

initializing an accumulator;

processing the motion data to generate motion information; and

quantizing the motion information into three levels then

incrementing the accumulator by a positive increment, if the motion information falls into a first level;

bypassing adjusting the accumulator, if the motion information falls into a second level; and

decrementing the accumulator by a negative increment, if the motion information falls into a third level;

comparing the accumulator to an accumulator limit; and

taking a position fix, if the accumulator meets the accumulator limit.

2. The method of claim 1 , wherein the act of processing the motion data to generate the motion information comprises counting a number of transitions during a period of time.

3. The method of claim 2 , wherein the act of quantizing the motion information into the three levels comprises:

categorizing the number of transitions to the first level, if the number of transitions is above a high threshold (High_TH);

categorizing the number of transitions to the second level, if the number of transitions is between the high threshold and above a low threshold, inclusive; and

categorizing the number of transitions to the third level, if the number of transitions is below the low threshold (Low_TH).

4. The method of claim 1 , wherein a magnitude of the positive increment is greater than a magnitude of the negative increment.

5. The method of claim 1 , wherein the act of taking the position fix, if the accumulator meets the accumulator limit, comprises:

incrementing a movement event counter, taking a position fix, if the accumulator meets the accumulator limit;

comparing the movement event counter to a threshold; and

taking the position fix, if the movement event counter meets the threshold.

6. A device for tracking a target, the device comprising:

a motion detection unit comprising

a sensor to provide motion data;

an accumulator;

a processor to process the motion data to generate motion information;

a quantizer to quantizing the motion information into three levels;

an adder to increment the accumulator by a positive increment, if the motion information falls into a first level;

logic to bypass adjusting the accumulator, if the motion information falls into a second level;

a subtractor to decrementing the accumulator by a negative increment, if the motion information falls into a third level; and

a comparator to compare the accumulator to an accumulator limit; and

a mobile tracking unit to take a position fix, if the accumulator meets the accumulator limit.

7. The device of claim 6 , wherein the processor comprises a counter to count a number of transitions during a period of time.

8. The device of claim 7 , wherein the three levels comprises:

the first level, if the number of transitions is above a high threshold (High_TH);

the second level, if the number of transitions is between the high threshold and above a low threshold, inclusive; and

the third level, if the number of transitions is below the low threshold (Low_TH).

9. The device of claim 6 , wherein a magnitude of the positive increment is greater than a magnitude of the negative increment.

10. A device for tracking a target associated with a motion detection unit and a mobile tracking unit, the device comprising:

means for initializing an accumulator;

means for processing the motion data to generate motion information; and

means for quantizing the motion information into three levels then

means for incrementing the accumulator by a positive increment, if the motion information falls into a first level;

means for bypassing adjusting the accumulator, if the motion information falls into a second level; and

means for decrementing the accumulator by a negative increment, if the motion information falls into a third level;

means for comparing the accumulator to an accumulator limit; and

means for taking a position fix, if the accumulator meets the accumulator limit.

11. The method of claim 10 , wherein the means for processing the motion data to generate the motion information comprises means for counting a number of transitions during a period of time.

12. The method of claim 11 , wherein the means for quantizing the motion information into the three levels comprises:

means for categorizing the number of transitions to the first level, if the number of transitions is above a high threshold (High_TH);

means for categorizing the number of transitions to the second level, if the number of transitions is between the high threshold and above a low threshold, inclusive; and

means for categorizing the number of transitions to the third level, if the number of transitions is below the low threshold (Low_TH).

13. The method of claim 10 , wherein a magnitude of the positive increment is greater than a magnitude of the negative increment.

14. The method of claim 10 , wherein the means for taking the position fix, if the accumulator meets the accumulator limit, comprises:

means for incrementing a movement event counter, taking a position fix, if the accumulator meets the accumulator limit;

means for comparing the movement event counter to a threshold; and

means for taking the position fix, if the movement event counter meets the threshold.

15. A computer-readable medium including program code stored thereon for use in a mobile device to track a target associated with a motion detection unit and a mobile tracking unit, the program code comprising:

program code to initialize an accumulator;

program code to process the motion data to generate motion information; and

program code to quantize the motion information into three levels then

program code to increment the accumulator by a positive increment, if the motion information falls into a first level;

program code to bypass adjusting the accumulator, if the motion information falls into a second level; and

program code to decrement the accumulator by a negative increment, if the motion information falls into a third level;

program code to compare the accumulator to an accumulator limit; and

program code to take a position fix, if the accumulator meets the accumulator limit.

16. The method of claim 15 , wherein the program code to process the motion data to generate the motion information comprises program code to counting a number of transitions during a period of time.

17. The method of claim 16 , wherein the program code to quantize the motion information into the three levels comprises:

program code to categorize the number of transitions to the first level, if the number of transitions is above a high threshold (High_TH);

program code to categorize the number of transitions to the second level, if the number of transitions is between the high threshold and above a low threshold, inclusive; and

program code to categorize the number of transitions to the third level, if the number of transitions is below the low threshold (Low_TH).

18. The method of claim 15 , wherein a magnitude of the positive increment is greater than a magnitude of the negative increment.

19. The method of claim 15 , wherein the program code to take the position fix, if the accumulator meets the accumulator limit, comprises:

program code to increment a movement event counter, taking a position fix, if the accumulator meets the accumulator limit;

program code to compare the movement event counter to a threshold; and

program code to take the position fix, if the movement event counter meets the threshold.

20. A method for tracking a target associated with a motion detection unit and a mobile tracking unit, the method comprising:

measuring motion of the target to produce motion data;

processing the motion data to generate motion information; and

comparing the motion information to a threshold; and

if the motion information is greater than the threshold, instructing the mobile tracking unit to take a position fix; and

if the motion information is less than the threshold, skipping to take a position fix.