Method and system for downhole clock having compensation

Details Method and system for downhole clock having compensation Method and system for downhole clock having compensation

2006-10-03

2006-10-03

Chang, Joseph (Department: 2817)

Oscillators

Frequency stabilization

Temperature or current responsive means in circuit

C331S158000, C331S066000, C331S069000, C331S070000, C331S044000, C367S086000, C367S038000, C367S025000

Reexamination Certificate

active

07116182

ABSTRACT:
A downhole crystal-based clock that is substantially insensitive to the factors that cause frequency deviation. The clock may be maintained at a predetermined temperature using a temperature sensing device and a heating device, where the predetermined temperature corresponds to the temperature at which the crystal experiences only slight frequency deviation as a function of temperature. A microprocessor may monitor the clock and compensate for long-term aging effects of the crystal according to a predetermined algorithm. The predetermined algorithm may represent long-term aging effects of the crystal which were derived by comparing the crystal clock to a more accurate clock (e.g., an atomic clock) prior to placing the clock downhole. In this manner, the crystal-based clock may be substantially free from the factors that cause frequency, and therefore time variations.

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John R. Vig. “Quartz Crystal Resonators and Oscillators For Frequency Control and Timing Applications, a Tutorial,” Chapters 2, 6 and 8; Jan. 2001.

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