# US 2016/0258795 A1 · Optical fiber cable > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0258795 A1 - Document ID: US20160258795A1 - Status: Published application - Kind: A1 - Application number: 15/029,480 - Filed: 2014-10-15 - Published: 2016-09-08 - Earliest claimed: 2013-10-15 - Assignees: Silixa Ltd. - Applicants: Silixa Ltd. - Inventors: Mahmoud Farhadiroushan; Daniel Finfer; Veronique Mahue; Tom Parker; Sergey Shatalin; Dmitry Strusevich - Web page: https://patentgrep.com/patent/US20160258795A1 ## CPC - G01F 1/661: using light - G01D 5/3537: {Optical fibre sensor using a particular arrangement of the optical fibre itself} - G02B 6/4415: {Cables for special applications (G02B6/4429, G02B6/4439, G02B6/4479 take precedence)} - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract Embodiments of the present invention provide a cable for optical fiber sensing applications formed from fiber wound around a cable core. A protective layer is then preferably placed over the top of the wound fiber, to protect the fiber, and to help keep it in place on the cable core. The cable core is preferably of a diameter to allow bend-insensitive fiber to be wound thereon with low bending losses. The effect of winding the fiber onto the cable core means that the longitudinal sensing resolution of the resulting cable is higher than simple straight fiber, when the cable is used with an optical fiber sensing system such as a DAS or DTS system. The achieved resolution for the resulting cable is a function of the fiber winding diameter and pitch, with a larger diameter and reduced winding pitch giving a higher longitudinal sensing resolution. ## Claims ### Claim 1 An optical fiber cable, comprising an optical fiber wound on a cable core. ### Claim at position 2 2-3. (canceled) ### Claim 4 (depends on 1) A cable according to claim 1, wherein the optical fiber is contiguously wound on the cable core. ### Claim 5 (depends on 1) A cable according to claim 1, wherein the pitch of the optical fiber windings is substantially constant along the length of the cable. ### Claim 6 (depends on 1) A cable according to claim 1, wherein the pitch of the optical fiber windings is variable along the cable. ### Claim 7 (depends on 6) A cable according to claim 6, wherein the cable comprises at least a first section of optical fiber windings and a second section of optical fiber windings, wherein the pitch of the optical fiber windings in the first section is higher than in the second section. ### Claim 8 (depends on 6) A cable according to claim 6, wherein the cable comprises at least a section of optical fiber windings wherein the helical pitch alters along the length of the section in a determinative manner. ### Claim 9 (depends on 8) A cable accord to claim 8, wherein the determinative manner is in accordance with a mathematical function, preferably a monotonic function. ### Claim 10 (depends on 6) A cable according to claim 6, and comprising a section where the fiber is not substantially helically wound around the cable core, but instead proceeds substantially parallel thereto. ### Claim 11 (depends on 6) A cable according to claim 6, wherein the pitch of the winding is angled in a first direction in a first part of the cable, and is angled in a second, generally opposite, direction in at least a second part of the cable. ### Claim 12 (depends on 1) A cable according to claim 1, wherein the optical fiber is wound on the cable core at an angle of up to 60 degrees, or more preferable less than 45 degrees, or even more preferably around 30 degrees. ### Claim 13 (depends on 1) A cable according to claim 1, and further comprising a frequency selective wrapping at one or more parts of the cable. ### Claim 14 (depends on 1) A cable according to claim 1, wherein the optical fiber is a fiber-in-metal-tube (FIMT) arrangements, the FIMT being bent into a spirally wound shape. ### Claim 15 (depends on 14) A cable according to claim 14, wherein there is no cable core as the bent FIMT is able to retain its shape. ### Claim 16 (depends on 1) A cable according to claim 1, wherein the optical fiber is wound on the cable core: i) helically, ii) cycloidally, and/or iii) in a general winding fashion. ### Claim 17 (depends on 1) A cable according to claim 1, wherein the cable core is solid along its length. ### Claim 18 (depends on 1) A cable according to claim 1, wherein the cable core has one or more hollow regions along its length. ### Claim 19 (depends on 18) A cable according to claim 18, wherein the hollow regions comprise one or more acoustically reactive masses, arranged to change the directional acoustic response of the cable core to incident acoustic energy. ### Claim 20 (depends on 19) A cable according to claim 19, wherein the masses are located in one or more notches formed in the cable core at the circumference thereof. ### Claim 21 (depends on 20) A cable according to claim 20, wherein there are plural notches circumferentially dispersed around the cable core. ### Claim 22 (depends on 19) A cable according to claim 19, wherein the acoustically reactive masses are resiliently mounted in the cable core. ### Claim 23 (depends on 19) A cable according to claim 19, wherein the acoustically reactive mass is a cross-member extending across the hollow region. ### Claim at position 23 24-25. (canceled) ### Claim 26 (depends on 1) A cable according to claim 1, wherein the cable core has a cross section that is any one of: i) circular; ii) polygonal; iii) arc-shaped; iv) horse-shoe shaped; or v) complementarily shaped to the outer surface of an article against which the cable is to be placed in use. ### Claim at position 25 27-31. (canceled) ### Claim 32 A distributed optical fiber sensing system, comprising: a distributed optical fiber sensor module; and an optical fiber cable, having a longitudinally extending wound optical fiber extending along at least part of the optical fiber cable, the distributed optical fiber sensor module arranged to couple with the cable so as to send and receive light into and from the optical fiber in the cable; the sensing resolution of the system being dependent upon the native sensing resolution of the distributed optical fiber sensor module, and the pitch and diameter of the optical fiber windings. ### Claim at position 27 33-34. (canceled) ### Claim 35 A method of flow monitoring in pipework, comprising: performing distributed acoustic sensing using a distributed acoustic sensing system provided with an optical fiber cable having a longitudinally extending wound optical fiber extending along at least part of the optical fiber cable, the distributed acoustic sensing system being used to obtain a set of acoustic data having a spatial resolution dependent on the native resolution of the distributed acoustic sensing system and the properties of the optical fiber cable, the optical fiber cable being arranged with respect to the pipework so as to be sensitive to acoustic energy within the pipework; processing the set of acoustic data to locate eddies within the pipework; and tracking the eddies' location to determine the flow within the pipework. ### Claim at position 29 36-37. (canceled)