System and method of adjusting channel properties for optical storage systems

Abstract

A method of adjusting channel properties of an optical storage system is disclosed to include the steps: Step 1) give a modify step, a trial step and a threshold, Step 2) give an initial point, Step 3) add an initial focus point to the trial step and measure the sum so as to obtain a first jitter value, Step 4) deduct the trial step from the initial focus point and measure the difference so as to obtain a second jitter value, Step 5) deduct the second jitter value from the first jitter value and judge if the difference is greater than the threshold or not, Step 6) deduct the modify step from the initial focus point and then return to step 3) when the difference obtained from step 5) is greater than the threshold, Step 7) deduct the first jitter value from the second jitter value and judge if the difference is greater than the threshold or not in case the difference obtained from step 5) is smaller than the threshold, Step 8) add the initial focus point to the modify step and then return to step 3) when the difference obtained from step 7) is greater than the threshold, and Step 9) keep the initial focus point and return to step 3) to continue search if the difference obtained from step 7) is smaller than the threshold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system block diagram of an optical storage system in accordance with the present invention.

FIG. 2 is a schematic drawing showing a high frequency boot around the cut-off frequency obtained through the low pass filter of the optical storage system according to the present invention.

FIG. 3 illustrates the jitter error defined as the phase error norm.

FIG. 4 a is a biased jitter histogram according to the present invention.

FIG. 4 b is an unbiased jitter histogram according to the present invention.

FIG. 5 is a flow chart showing the channel properties adjustment operation of the jitter servo control unit JSCU according to the present invention.

FIG. 6 is a U curve obtained from the channel properties adjustment operation of the jitter servo control unit JSCU according to the present invention.

FIG. 7 is a flow chart illustrating the correction of the settings of the servo and RF signal of an optical storage system according to the present invention.

Claims

1. A method of adjusting channel properties of an optical storage system for enabling the read-write head of the optical storage system to search from control variables of the optical storage system the optimal focus point that has the least jitter value and high sensitivity, the method comprising the steps: Step 1) give a modify step, a trial step and a threshold;Step 2) give an initial point;Step 3) add an initial focus point to said trial step and measure the sum so as to obtain a first jitter value;Step 4) deduct the trial step from the initial focus point and measure the difference so as to obtain a second jitter value;Step 5) deduct said second jitter value from said first jitter value and judge if the difference is greater than said threshold THD or not;Step 6) deduct said modify step from said initial focus point and then return to Step 3) when the difference obtained from step 5) is greater than said threshold;Step 7) deduct said first jitter value from said second jitter value and judge if the difference is greater than said threshold THD or not in case the difference obtained from step 5) is smaller than said threshold;Step 8) add said initial focus point to said modify step and then return to step 3) when the difference obtained from step 7) is greater than said threshold;Step 9) keep said initial focus point and return to step 3) to continue search if the difference obtained from step 7) is smaller than said threshold.

2. The method as claimed in claim 1, wherein said trial step is greater than said modify step.

3. The method as claimed in claim 1, wherein said threshold is to protect trial and error steps against noises and interferences, preventing a drift.

4. The method as claimed in claim 1, wherein when measuring said first jitter value and said second jitter value, the method searches at least one parameter in proper order on the same time so as to quickly obtain said first jitter value and said second jitter value.

5. The method as claimed in claim 4, wherein said at least one parameter includes at least one of the focus error, tracking error and tilt error.

6. A channel property adjustable optical storage system comprising at least: a RF (radio frequency) filter adapted to receive a RF (radio frequency) signal outputted from an optical detector of the optical storage system;a phase-lock-loop coupled to said RF filter and adapted to receive said RF signal and to output a corresponding phase signal;a jitter measuring unit respectively coupled to said RF filter and said phase-lock-loop and adapted to obtain a phase difference subject to said phase signal and said RF signal and then to obtain a jitter value subject to said phase difference; anda jitter servo control unit coupled to said jitter measuring unit and adapted to make a servo control subject to said jitter value.

7. The channel property adjustable optical storage system as claimed in claim 6, wherein said RF filter is a low pass filter.

8. The channel property adjustable optical storage system as claimed in claim 6, wherein said low pass filter is adapted to filter out high frequency noises, to obtain a high boost around the cutoff frequency for compensating inner symbol interferences (ISI) of said RF signal, said boost being determined subject to said jitter value.

9. The channel property adjustable optical storage system as claimed in claim 6, wherein said phase difference signal is a signed value; said jitter measuring unit is adapted to selectively use 1-norm, 2-norm or the infinite norm of a window to obtain the maximum absolute value from the window so as to convert said signed value into a biased jitter value.

10. The channel property adjustable optical storage system as claimed in claim 9, wherein said jitter measuring unit counts the number of the biased jitter value falling to every pit width of the RF signal so as to obtain a biased jitter histogram having the center thereof based on the center of the statistic center.

11. The channel property adjustable optical storage system as claimed in claim 10, wherein said biased jitter value is real-time measured and utilized simultaneously or off-time measured and recorded then locked-up as a pre-determined table.

12. The channel property adjustable optical storage system as claimed in claim 10, wherein said jitter measuring unit further removes said statistic center from said biased jitter histogram, thereby obtaining an unbiased jitter histogram.

13. The channel property adjustable optical storage system as claimed in claim 12, wherein said jitter servo control unit receives said unbiased jitter histogram and uses a search method to search the optimal focus point from control variables of the system, said optimal focus point having the least jitter value and a high sensitivity.

14. The channel property adjustable optical storage system as claimed in claim 13, wherein said search method comprises the steps of: Step 1) give a modify step, a trial step and a threshold;Step 2) give an initial point;Step 3) add an initial focus point to said trial step and measure the sum so as to obtain a first jitter value;Step 4) deduct the trial step from the initial focus point and measure the difference so as to obtain a second jitter value;Step 5) deduct said second jitter value from said first jitter value and judge if the difference is greater than said threshold THD or not;Step 6) deduct said modify step from said initial focus point and then return to Step 3) when the difference obtained from step e) is greater than said threshold;Step 7) deduct said first jitter value from said second jitter value and judge if the difference is greater than said threshold THD or not in case the difference obtained from step 5) is smaller than said threshold;Step 8) add said initial focus point to said modify step and then return to step 3) when the difference obtained from step 7) is greater than said threshold;Step 9) keep said initial focus point and return to step 3) to continue search if the difference obtained from step 7) is smaller than said threshold.

15. The channel property adjustable optical storage system as claimed in claim 14, wherein said trial step is greater than said modify step.

16. The channel property adjustable optical storage system as claimed in claim 14, wherein said threshold is to protect trial and sear steps against noises and interferences, preventing a drift.

17. The channel property adjustable optical storage system as claimed in claim 14, wherein when measuring said first jitter value and said second jitter value, the method searches at least one parameter in proper order on the same time so as to quickly obtain said first jitter value and said second jitter value.

18. The channel property adjustable optical storage system as claimed in claim 17, wherein said at least one parameter includes at least one of the focus error, tracking error and tilt error.

19. A method of correcting the settings of the servo and RF signal of an optical storage system, comprising the steps of: Step 1) compare a RF signal to the recovery time pulse thereof to obtain a phase difference signal;Step 2) convert said phase difference signal into a bias jitter value;Step 3) count the number of the biased jitter value falling to every pit width of said RF signal so as to obtain a biased jitter histogram having the center thereof based on the center of the statistic center;Step 4) deduct the statistic center to obtain an unbiased jitter histogram; andStep 5) send said unbiased jitter histogram to a servo for search so as to obtain the least jitter value and the optimal focus point.

20. The method as claimed in claim 19, wherein said biased jitter value is further classified as NT-based and NT-MT-based jitter.

21. The method as claimed in claim 20, wherein said NT-based jitter value has a statistic on the RF width only; said NT-MT-based jitter value has a statistic on different adjacent NT-MT and high-low combinations.

22. The method as claimed in claim 21, wherein said biased jitter value is measured and recorded in a statistic table for inquiry.

23. The method as claimed in claim 22, wherein said biased jitter value is real-time or off-time measured.