| 摘要 |
A method and apparatus are disclosed for providing a fiber optic distribution network between a central office and a group of users generally in a localized area, a continuous optical fiber primary loop in communication with the central office passing in the vicinity of each user, patch devices or units being arranged in the loop for coupling users with the central office through optical fibers in the primary loop. Patch units are preferably arranged in spaced-apart relation along the primary loop, each establishing continuity in selected fibers providing communication access to users associated with other patch units while providing communication access with the central office for its own user or users. Each patch unit is preferably adapted for forming two secondary loops between the user and central location, the two secondary loops including adjacent fibers on opposite sides of the primary loop in order to assure service to the particular user in the event of loss of communication access at any point along the primary loop, sensing and switching means being provided for automatically shifiting communication from one secondary loop to another in the event of loss of communication access in the one secondary loop.
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