Method and apparatus for measuring optical distances
First Claim
1. A method for determining the optical distance along a buried optical fiber from a particular location to a central facility, comprising the steps of:
- intentionally applying a stress to the fiber at said particular location;
transmitting to the central facility a timing signal of known periodicity in synchronism with the application of the intentional stress;
detecting at the central facility the stress on the fiber;
establishing, from the timing signal a time difference between application of the stress and its detection at the central facility; and
determining the optical distance from the particular location to the central facility in accordance with the time difference.
2 Assignments
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Accused Products
Abstract
The optical distance along a buried optical fiber (12) from a particular location (13) therealong to a central facility (10) is measured by first applying an intentional stress to the fiber in the form of a vibration signal (35) transmitted into the ground. A timing signal (36) is transmitted to the central facility (10) in synchronism with the application of the stress. Using the timing signal as a reference, the central facility can determine the time difference between when the stress was applied, and when the central facility detected the stress. From the time difference, and a knowledge of the propagation rate of the timing signal, the central facility can establish the optical distance to the particular location at which the stress was applied.
27 Citations
18 Claims
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1. A method for determining the optical distance along a buried optical fiber from a particular location to a central facility, comprising the steps of:
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intentionally applying a stress to the fiber at said particular location; transmitting to the central facility a timing signal of known periodicity in synchronism with the application of the intentional stress; detecting at the central facility the stress on the fiber; establishing, from the timing signal a time difference between application of the stress and its detection at the central facility; and determining the optical distance from the particular location to the central facility in accordance with the time difference. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for determining the location of a fault on a buried optical fiber, comprising the steps of:
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establishing an optical measure of the distance of the fault from a central facility; intentionally applying a stress to the fiber at a particular location; transmitting to the central facility a timing signal of known periodicity in synchronism with the application of the intentional stress; detecting at the central facility the stress on the fiber; establishing, from the timing signal a time difference between application of the stress and its detection at the central facility; determining the optical distance from the particular location to the central facility in accordance with the time difference; and establishing the location of the fault in accordance with the difference between the distance of the fault and the central location and the distance from the particular location and the central facility. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. Apparatus for determining the optical distance along a buried optical fiber from a particular location to a central facility, comprising the steps of:
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means intentionally applying a stress to the fiber at said particular location; means for transmitting to the central facility a timing signal of known periodicity in synchronism with the application of the intentional stress; detecting means at the central facility the stress on the fiber; and processing means for establishing from the timing signal a time difference between application of the stress and its detection at the central facility and for determining the optical distance from the particular location to the central facility in accordance with the time difference. - View Dependent Claims (16, 17, 18)
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Specification