Patent US9362929

Controlling oscillators
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US9362929

1. A computer implemented method for controlling an oscillator, the method comprising: (6) (2)

determining a first statistical correlation between multiple error values, each error value being indicative of a measurement of a frequency difference between the oscillator and a frequency reference over a period of time, and

determining a control value to control the oscillator by maximising a second statistical correlation between a frequency difference at a time of application of the control value to the oscillator and a correction caused by the application of the control value, the frequency difference being a statistical variable estimated based on the first statistical correlation and an application time value indicative of the time of application of the control value to the oscillator.

2. The method of claim 1, wherein (0) (2)

3. The method of claim 1, wherein determining the control value comprises determining the control value based on noise data indicative of statistical noise characteristics of the oscillator. (1) (0)

5. The method of claim 1, wherein determining the control value comprises: (1) (2)

determining multiple weighting coefficients for the multiple error values based on the multiple error values; and

determining the control value to control the oscillator based on the multiple error values modified according to the multiple weighting coefficients.

6. The method of claim 5, wherein determining the control value comprises determining a linear combination of the multiple error values weighted by the multiple weighting coefficients. (1) (0)

8. The method of claim 6, wherein (0) (3)

7. The method of claim 1, wherein (2) (2)

each of the multiple error values is associated with a measurement duration value indicative of a duration of the measurement of the frequency difference, and

determining the control value comprises determining the control value based on the measurement duration value associated with each of the multiple error values.

9. The method of claim 7, wherein the duration of the measurement is defined between two exposure periods of the frequency reference to the frequency of the oscillator such that each of the multiple error values is indicative of an accumulated phase difference between the oscillator and the frequency reference. (0)

10. The method of claim 7, further comprising performing an optimisation to determine the multiple duration values for obtaining the multiple error values. (0)

11. The method of claim 1, wherein determining the control value comprises determining the control value based on a transfer function indicative of an influence of fluctuations of the oscillator on the multiple error values. (1) (0)

13. A non-transitory computer readable medium with an executable program stored thereon that when executed causes the computer to perform the method of claim 1. (0)

14. A computer system for controlling an oscillator, the computer system comprising: (0) (2)

15. A method for generating a clock signal, the method comprising: (1) (6)

generating the clock signal based on oscillations of an oscillator;

performing multiple measurements of a frequency difference between the oscillator and a frequency reference over a period of time;

determining multiple error values such that each error value is indicative of one of the multiple measurements;

determining a first statistical correlation between the multiple error values;

applying the control value to the oscillator at the time of application.

16. The method of claim 15, wherein measuring the frequency difference comprises measuring an accumulated phase difference. (0)

17. A clock comprising: (1) (4)

an oscillator and a detector to generate a clock signal based on oscillations of the oscillator;

a frequency reference;

a measurement system to perform multiple measurements of a frequency difference between the oscillator and the frequency reference over a period of time; and

a processor to determine multiple error values such that each error value is indicative of one of the multiple measurements;

to determine a first statistical correlation between the multiple error values;

to determine a control value to control the oscillator by maximising a second statistical correlation between a frequency difference at a time of application of the control value to the oscillator and a correction caused by the application of the control value, the frequency difference being a statistical variable estimated based on the first statistical correlation and an application time value indicative of the time of application of the control value to the oscillator; and

to apply the control value to the oscillator at the time of application.

18. The clock of claim 17, wherein the frequency reference is an atomic frequency reference. (0)

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Patent US9362929

Controlling oscillators

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