A data processing system for registering an optical fiber having a core, the core including multiple optical gratings closely-spaced and written along the core such that there is a repeated pattern along the core, the data processing system comprising: a memory configured to store predetermined reference reflection data and measurement reflection data determined for a length of the core and detected from interferometric patterns corresponding to scatter reflections received from the core; and data processing circuitry coupled to the memory, the data processing circuitry configured to: filter or window a central spectral peak of the optical gratings out of the reference reflection data to produce filtered reference reflection data; filter or window a central spectral peak of the optical gratings out of the measurement reflection data to produce filtered measurement reflection data; produce multiple correlation values by correlating: multiple segments within a search range of segments of the filtered measurement reflection data with a selected segment of the filtered reference reflection data corresponding to a desired fiber segment, or a selected segment of the filtered measurement reflection data with multiple segments within a search range of segments of the filtered reference reflection data; determine a greatest correlation value of the multiple correlation values; and identify a location along the core of a segment of the filtered measurement reflection data corresponding to the greatest correlation value based on a location along the core of a segment of the filtered reference reflection data corresponding to the greatest correlation value. a memory configured to store predetermined reference reflection data and measurement reflection data determined for a length of the core and detected from interferometric patterns corresponding to scatter reflections received from the core; and data processing circuitry coupled to the memory, the data processing circuitry configured to: filter or window a central spectral peak of the optical gratings out of the reference reflection data to produce filtered reference reflection data; filter or window a central spectral peak of the optical gratings out of the measurement reflection data to produce filtered measurement reflection data; produce multiple correlation values by correlating: multiple segments within a search range of segments of the filtered measurement reflection data with a selected segment of the filtered reference reflection data corresponding to a desired fiber segment, or a selected segment of the filtered measurement reflection data with multiple segments within a search range of segments of the filtered reference reflection data; determine a greatest correlation value of the multiple correlation values; and identify a location along the core of a segment of the filtered measurement reflection data corresponding to the greatest correlation value based on a location along the core of a segment of the filtered reference reflection data corresponding to the greatest correlation value. filter or window a central spectral peak of the optical gratings out of the reference reflection data to produce filtered reference reflection data; filter or window a central spectral peak of the optical gratings out of the measurement reflection data to produce filtered measurement reflection data; produce multiple correlation values by correlating: multiple segments within a search range of segments of the filtered measurement reflection data with a selected segment of the filtered reference reflection data corresponding to a desired fiber segment, or a selected segment of the filtered measurement reflection data with multiple segments within a search range of segments of the filtered reference reflection data; determine a greatest correlation value of the multiple correlation values; and identify a location along the core of a segment of the filtered measurement reflection data corresponding to the greatest correlation value based on a location along the core of a segment of the filtered reference reflection data corresponding to the greatest correlation value.