1. A probability density function separating apparatus that separates a predetermined component in a given probability density function, comprising:
a domain transforming section that is supplied with the probability density function and transforms the probability density function into a spectrum in a predetermined variable axis; and
a deterministic component computing section that multiplies a multiplier coefficient according to a type of distribution of a deterministic component included in the given probability density function by a value, in the variable axis, of a first null of the spectrum and computes a peak to peak value of the probability density function with the deterministic component.
2. The probability density function separating apparatus as claimed in claim 1, wherein the probability density function separating apparatus previously stores the multiplier coefficient every type of distribution of the deterministic component and computes the peak to peak value by means of the multiplier coefficient corresponding to the selected type of distribution of the deterministic component.
3. The probability density function separating apparatus as claimed in claim 1, further comprising a standard deviation computing section that computes standard deviation of a random component included in the probability density function based on the spectrum.
4. The probability density function separating apparatus as claimed in claim 3, wherein the standard deviation computing section computes the standard deviation based on a magnitude of a predetermined variable component, in the variable axis, of the spectrum.
5. The probability density function separating apparatus as claimed in claim 4, wherein the standard deviation computing section computes the standard deviation based on a ratio between a magnitude of a first variable component and a magnitude of a second variable component of the spectrum.
6. The probability density function separating apparatus as claimed in claim 5, wherein the standard deviation computing section calculates a value obtained by dividing the ratio between the magnitude of the first variable component and the magnitude of the second variable component of the spectrum by a ratio between a magnitude of the first variable component and a magnitude of the second variable component of a spectrum of the deterministic component, and computes the standard deviation based on this value.
7. The probability density function separating apparatus as claimed in claim 3, further comprising a random component computing section that computes a probability density function with a random component based on the standard deviation.
8. The probability density function separating apparatus as claimed in claim 7, wherein
the deterministic component computing section comprises:
a candidate value computing section that previously stores the multiplier coefficient every type of distribution of the deterministic component and computes each peak to peak value when each multiplier coefficient is used;
a candidate function computing section that respectively computes a probability density function with the deterministic component based on each peak to peak value computed from the candidate value computing section;
a synthesizing section that respectively generates composite probability density functions made by respectively synthesizing each probability density function with the deterministic component computed from the candidate function computing section and the probability density function with the random component computed from the random component computing section; and
a selecting section that compares each composite probability density function generated from the synthesizing section with the given probability density function and selects one peak to peak value from the plurality of peak to peak values computed from the candidate value computing section based on the comparison result.
9. The probability density function separating apparatus as claimed in claim 1, wherein the deterministic component computing section detects the value, in the variable axis, of the first null of the spectrum based on a peak of a spectrum obtained by second-order differentiating the spectrum output from the domain transforming section by the variable axis.
10. The probability density function separating apparatus as claimed in claim 1, wherein
the deterministic component computing section computes a probability density function corresponding to the deterministic component, based on the peak to peak value, and
the probability density function separating apparatus further includes a random component computing section that computes a random component included in the given probability density function, by dividing the spectrum transformed by the domain transforming section by an absolute value (a magnitude spectrum) of the probability density function corresponding to the deterministic component which is computed by the deterministic component computing section.
11. The probability density function separating apparatus as claimed in claim 1, wherein
the given probability density function is a probability density function with a noise component included in a signal under test, and
the probability density function separating apparatus further comprises a total jitter computing section that computes a value of total jitter included in the signal under test, based on the peak to peak value computed by the deterministic component computing section.
12. The probability density function separating apparatus as claimed in claim 11, further comprising:
a random component computing section that computes a random component included in the probability density function based on the spectrum, wherein
the total jitter computing section computes the value of the total jitter based on the peak to peak value and the random component.
13. The probability density function separating apparatus as claimed in claim 11, wherein
the total jitter computing section is supplied with a random component included in the probability density function, and computes the value of the total jitter based on the peak to peak value and the random component.
14. The probability density function separating apparatus as claimed in claim 11, further comprising
a deciding section that decides whether the signal under test is acceptable based on the value of the total jitter which is computed by the total jitter computing section.
15. A probability density function separating method for separating a predetermined component from a given probability density function, comprising:
a domain transforming step of being supplied with the probability density function and transforming the probability density function into a spectrum in a predetermined variable axis; and
a deterministic component computing step of multiplying a multiplier coefficient according to a type of distribution of a deterministic component included in the given probability density function by a value, in the variable axis, of a first null of the spectrum and computing a peak to peak value of the probability density function with the deterministic component.
16. The probability density function separating method as claimed in claim 15, further comprising a standard deviation computing step of computing standard deviation of a random component included in the probability density function based on the spectrum.
17. An article comprising machine executable instructions tangibly embodied on a non-transitory machine readable medium, the instructions operable to cause one or more machines to make a computer function as a probability density function separating apparatus that separates a predetermined component from a given probability density function, the instructions making the computer function as: a domain transforming section that is supplied with the probability density function and transforms the probability density function into a spectrum in a predetermined variable axis; and a deterministic component computing section that multiplies a multiplier coefficient according to a type of distribution of a deterministic component included in the given probability density function by a value, in the variable axis, of the first null of the spectrum and computes a peak to peak value of the probability density function with the deterministic component.
18. The program as claimed in claim 17, the program further making the computer function as a standard deviation computing section that computes standard deviation of a random component included in the probability density function based on the spectrum.
19. The program as claimed in claim 18, the program making the computer function as the standard deviation computing section that calculates a value obtained by dividing a ratio between a magnitude of a first variable component and a magnitude of a second variable component of the spectrum of the probability density function by a ratio between a magnitude of the first variable component and a magnitude of the second variable component of a spectrum of the deterministic component and computes the standard deviation based on this value.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A tilt controller comprising:
a control signal generator generating a first control signal and a second control signal to control an actuator adjusting a tilt of a pickup that reads data recorded on an optical disc;
a reference control signal generator generating a reference control signal using the first control signal and the second control signal;
a driving signal generator generating signals to drive the actuator using the first and second control signals and the reference control signal;
a first control signal protector preventing the first control signal from being distorted by the reference control signal generator; and
a second control signal protector preventing the second control signal from being distorted by the reference control signal generator.
2. The controller as claimed in claim 1, wherein:
the first control signal protector prevents a voltage of the first control signal from being changed by a first signal output from a first terminal of the reference control signal generator, and
the second control signal protector prevents a voltage of the second control signal from being changed by a second signal output from a second terminal of the reference control signal generator.
3. The controller as claimed in claim 2, wherein:
the first control signal protector comprises a first voltage follower having an input connected to the first control signal and an output connected to the first terminal of the reference control signal generator, and
the second control signal protector comprises a second voltage follower having an input connected to the second control signal and an output connected to the second terminal of reference control signal generator.
4. An optical reproducing apparatus comprising:
a pickup reading data recorded on an optical disc;
an actuator adjusting a tilt of the pickup;
a control signal generator generating a first control signal and a second control signal to control the actuator adjusting the tilt of the pickup;
a reference control signal generator generating a reference control signal using the first control signal and the second control signal;
a driving signal generator generating signals to drive the actuator using the first and second control signals and the reference control signal;
a first control signal protector preventing the first control signal from being distorted by the reference control signal generator; and
a second control signal protector preventing the second control signal from being distorted by the reference control signal generator.
5. The apparatus as claimed in claim 4, wherein:
the first control signal protector prevents a voltage of the first control signal from being changed by a first signal output from a first terminal of the reference control signal generator, and
the second control signal protector prevents a voltage of the second control signal from being changed by a second signal output from a second terminal of the reference control signal generator.
6. The apparatus as claimed in claim 5, wherein:
the first control signal protector comprises a first voltage follower having an input connected to the first control signal and an output connected to the first terminal of the reference control signal generator, and
the second control signal protector comprises a second voltage follower having an input connected to the second control signal and an output connected to the second terminal of reference control signal generator.
7. An optical reproducing apparatus comprising:
a pickup reading data recorded on an optical disc;
an actuator adjusting a tilt of the pickup;
a control signal generator adding a focus control signal and a tilt control signal to generate a first control signal and subtracting the focus control signal and the tilt control signal to generate a second control signal;
first and second voltage followers buffering the first and second control signals, respectively;
a voltage divider generating a reference control signal based on voltage division of the first and second buffered control signals; and
a driving signal generator, comprising:
first, second and third amplifiers amplifying the first, second and reference control signals, respectively, and
first, second and third level shifters which shift a level of the amplified first, second and reference control signals, respectively, to drive the actuator.
8. A control circuit for preventing distortion in signals used to drive an actuator of an optical pickup, the circuit comprising:
a control signal generator generating first and second control signals based on a focus control signal and a tilt control signal;
first and second voltage followers buffering the first and second control signals, respectively;
a reference control signal generator generating a reference control signal to drive the actuator using the first and second buffered control signals; and
an actuator driving signal generator driving the actuator based on the non-buffered first and second control signals and the reference control signal.