# US 2014/0153921 A1 · Method and apparatus for detecting uncharacteristic power level changes of an optical signal > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153921 A1 - Document ID: US20140153921A1 - Status: Published application - Kind: A1 - Application number: 13/693,594 - Filed: 2012-12-04 - Published: 2014-06-05 - Earliest claimed: 2012-12-04 - Assignees: ADVA Optical Networking SE - Applicants: ADVA Optical Networking SE - Inventors: David FOX; Lawrence T. DILLARD, III; Neil GRAYSON - Web page: https://patentgrep.com/patent/US20140153921A1 ## CPC - H04B 10/07: Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems - H04B 10/075: using an in-service signal (H04B10/071 takes precedence) - H04B 10/85: Protection from unauthorised access, e.g. eavesdrop protection - H04B: TRANSMISSION ## Abstract A monitoring apparatus for detecting uncharacteristic short-term power level changes of an optical signal transmitted through an optical fiber, said monitoring apparatus comprising a power level variance calculation unit adapted to calculate a power level variance on the basis of a long-term power level and a current power level of said optical signal and a short-term variance filter adapted to filter transient changes indicated by the calculated power level variance and to generate a trouble occurrence indication indicating an uncharacteristic short-term power level change, if the filtered power level variance exceeds a predetermined power level variance. ## Claims ### Claim 1 A monitoring apparatus for detecting uncharacteristic power level changes of an optical signal transmitted through an optical fiber,said monitoring apparatus comprising: a power level variance calculation unit adapted to calculate a power level variance on the basis of a long-term power level and a current power level of said optical signal and a short-term variance filter adapted to filter transient changes indicated by the calculated power level variance and to generate a trouble occurrence indication indicating an uncharacteristic short-term power level change, if the filtered power level variance exceeds a predetermined power level variance. ### Claim 2 (depends on 1) The monitoring apparatus according to claim 1, wherein said monitoring apparatus further comprises a long-term differential signal filter adapted to filter measured power levels of said optical signal to provide the long-term power level applied to said power level variance calculation unit. ### Claim 3 (depends on 1) The monitoring apparatus according to claim 1, wherein the power levels of said optical signal are measured by a fiber optic data receiver adapted to receive data signals via the optical fiber. ### Claim 4 (depends on 3) The monitoring apparatus according to claim 3, wherein the measured power levels comprise power levels measured by a near-end fiber optic data receiver and/or power levels measured by a far-end fiber optic data receiver and transported via the optical fiber. ### Claim 5 (depends on 4) The monitoring apparatus according to claim 4, wherein the power levels measured by the far-end fiber optic data receiver are encoded by a remote data signal processing unit and transported via the optical fiber to the near-end fiber optic data receiver being connected to a decoding unit adapted to decode the received encoded power levels. ### Claim 6 (depends on 5) The monitoring apparatus according to claim 5 comprising an oversampling filter receiver and/or the decoded power levels supplied by said decoding unit and to perform an oversampling of the received power levels with a predetermined oversampling ratio to reduce aliasing and signal noise and/or to increase a resolution of an analog to digital converter provided in said near-end fiber optic data receiver and/or in said far-end fiber optic data receiver. ### Claim 7 (depends on 6) The monitoring apparatus according to claim 6, wherein a power level sampling unit is adapted to receive periodically the oversampled power levels from said oversampling filter and to supply a current power level to said power level variance calculation unit and a set of power levels to said long-term differential signal filter. ### Claim 8 (depends on 7) The monitoring apparatus according to claim 7, wherein said long-term differential signal filter is adapted to perform a modified exponential moving average (MEMA) calculation on the basis of the power levels provided by said power level sampling unit. ### Claim 9 (depends on 8) The monitoring apparatus according to claim 8, further comprising a database which is adapted to store the power levels provided by the power level sampling unit, and/or the long-term power levels calculated by the long-term differential signal filter and/or the power level variances calculated by said power level variance calculation unit and/or the trouble occurrence indications generated by said short-term variance filter. ### Claim 10 (depends on 1) The monitoring apparatus according to claim 1, wherein said trouble occurrence indication generated by said short-term variance filter is output to a terminal of a remote network operator and/or to a terminal of a local system operator. ### Claim 11 (depends on 1) The monitoring apparatus according to claim 1, wherein said short-term variance filter is adapted to generate a trouble occurrence clear indication if the filtered power level variance is less than the predetermined power level variance. ### Claim 12 (depends on 6) The monitoring apparatus according to claim 6, wherein the oversampling ratio of said oversampling filter is set to four. ### Claim 13 (depends on 1) The monitoring apparatus according to claim 1, wherein the trouble occurrence indication is generated by said short-term variance filter, if the filtered power level variance exceeds ±1 dB within a predetermined time period. ### Claim 14 (depends on 3) The monitoring apparatus according to claim 3, wherein said fiber optic data receiver is integrated in a pluggable SFP-transceiver. ### Claim 15 (depends on 1) An optical network access apparatus comprising at least one pluggable transceiver having a fiber optic data receiver adapted to measure power levels of a received optical signal and comprising a monitoring apparatus according to claim 1 adapted to detect uncharacteristic short-term power level changes in said optical signal. ### Claim 16 (depends on 15) An optical transmission system comprising optical network access apparatuses according to claim 15 connected to each other via at least one optical fiber. ### Claim 17 A method for detecting uncharacteristic short-term power level changes of an optical signal transmitted through an optical fiber said method comprising the steps of: (a) calculating a power level variance on the basis of a long-term power level and a current power level of said optical signal and (b) filtering transient changes indicated by the calculated power level variance and generating a trouble occurrence indication indicating an uncharacteristic short-term power level change if the filtered power level variance exceeds a predetermined power level variance. ### Claim 18 A method for detecting uncharacteristic short-term and/or long-term power level changes or fluctuations of an optical signal transmitted through an optical fiber to a transceiver wherein a first trouble occurrence indication indicating an uncharacteristic short-term power level change is generated if a filtered power level variance exceeds a predetermined power level variance; a second trouble occurrence indication indicating a long-term power level change is generated if a current power level is outside an operating power range of the transceiver. ### Claim 19 (depends on 17, 18) An optical network access apparatus comprising a monitoring apparatus adapted to perform the method of claim 17 or 18.