# US 11,444,716 B2 · Optical transmission system and carrier monitoring apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,444,716 B2 - Document ID: US11444716B2 - Status: Granted - Kind: B2 - Application number: 17/426,800 - Filed: 2020-01-31 - Published: 2022-04-28 - Granted: 2022-09-13 - Earliest claimed: 2019-02-01 - Assignees: Nippon Telegraph and Telephone Corporation - Applicants: Nippon Telegraph and Telephone Corporation - Inventors: Takashi Mitsui; Toshiaki Shitaba - Web page: https://patentgrep.com/patent/US11444716B2 ## CPC - H04B 10/25751: {Optical arrangements for CATV or video distribution (adaptations of television systems for optical transmission H04N7/22)} - H04J 14/0227: {Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation} - H04B 10/075: using an in-service signal (H04B10/071 takes precedence) - H04B 10/293: Signal power control - H04J 1/00: Frequency-division multiplex systems (H04J14/00 takes precedence) - H04J 14/0221: {Power control, e.g. to keep the total optical power constant} - H04L 27/10: Frequency-modulated carrier systems, i.e. using frequency-shift keying (H04L27/32 takes precedence) - H04B 10/07955: {Monitoring or measuring power} - H04B: TRANSMISSION - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An optical transmission system includes: first and second optical transmitting units for respectively transmitting first and second optical signals that are obtained, respectively, as a result of first and second frequency-multiplexed multi-channel signals being converted by means of FM batch conversion; a carrier monitoring function unit for monitoring each carrier signal included in the optical signals; an output adjustment unit for adjusting signal intensities of the optical signals and outputting the optical signals; a multiplexer for outputting a multiplexed signal of the optical signals; an amplifier for amplifying the multiplexed signal; and first and second optical receiving units for receiving the respective optical signals included in the amplified multiplexed signal. The output adjustment unit adjusts the respective signal intensities of the optical signals such that the signal intensity at each optical receiving unit is larger than or equal to a predetermined value. The carrier monitoring function unit updates the predetermined values based on a minimum optical sensitivity that is calculated based on the amount of frequency deviation of each carrier signal included in the optical signals. ## Claims ### Claim 1 An optical transmission system comprising: a first optical transmitting unit for transmitting a first optical signal having a first wavelength that is obtained as a result of first frequency-multiplexed multi-channel signals being converted by means of FM batch conversion; a second optical transmitting unit for transmitting a second optical signal having a second wavelength different from the first wavelength that is obtained as a result of second frequency-multiplexed multi-channel signals being converted by means of FM batch conversion; a carrier monitoring function unit for acquiring the first optical signal and monitoring each carrier signal included in the acquired optical signal; an output adjustment unit for acquiring the first optical signal and the second optical signal, adjusting signal intensities of the acquired optical signals, and outputting the optical signals; a multiplexer for multiplexing the first optical signal and the second optical signal that have been subjected to signal intensity adjustment by the output adjustment unit, and outputting a multiplexed signal; an amplifier for amplifying the multiplexed signal; a first optical receiving unit for receiving the first optical signal included in the multiplexed signal that has been amplified by the amplifier; and a second optical receiving unit for receiving the second optical signal included in the multiplexed signal that has been amplified by the amplifier, wherein the carrier monitoring function unit obtains an amount of frequency deviation of each carrier signal included in the first optical signal, and calculates a minimum optical sensitivity at the first optical receiving unit based on the amount of frequency deviation, and the output adjustment unit adjusts the signal intensities of the acquired first optical signal and second optical signal such that the signal intensity of the first optical signal received by the first optical receiving unit is larger than or equal to a first predetermined value, and the signal intensity of the second optical signal received by the second optical receiving unit is larger than or equal to a second predetermined value, and updates the first predetermined value based on the minimum optical sensitivity at the first optical receiving unit calculated by the carrier monitoring function unit. ### Claim 2 (depends on 1) The optical transmission system according to claim 1, wherein the output adjustment unit adjusts the signal intensities of the first optical signal and the second optical signal such that a signal intensity of the multiplexed signal output from the amplifier is a third predetermined value. ### Claim 3 (depends on 1) The optical transmission system according to claim 1, wherein the output adjustment unit adjusts the signal intensities of the first optical signal and the second optical signal based on insertion loss that occurs in the multiplexer, and transmission loss that occurs between the amplifier and the first optical receiving unit and between the amplifier and the second optical receiving unit. ### Claim 4 (depends on 1) The optical transmission system according claim 1, wherein the carrier monitoring function unit further acquires the second optical signal, obtains an amount of frequency deviation of each carrier signal included in the second optical signal, and calculates a minimum optical sensitivity at the second optical receiving unit based on the amount of frequency deviation, and the output adjustment unit further updates the second predetermined value based on the minimum optical sensitivity at the second optical receiving unit calculated by the carrier monitoring function unit. ### Claim 5 (depends on 1) The optical transmission system according to claim 1, further comprising a second multiplexer for multiplexing the first optical signal transmitted from the first optical transmitting unit and the second optical signal transmitted from the second optical transmitting unit, wherein the output adjustment unit acquires an optical signal multiplexed by the second multiplexer, demultiplexes the acquired optical signal into the first optical signal and the second optical signal, adjusts signal intensities of the demultiplexed first optical signal and second optical signal, and outputs the first optical signal and the second optical signal. ### Claim 6 (depends on 1) The optical transmission system according claim 1, wherein the output adjustment unit calculates a first necessary signal intensity that is a signal intensity that the first optical signal included in the multiplexed signal output from the amplifier is required to have, based on the first predetermined value, insertion loss that occurs in the multiplexer, and transmission loss that occurs between the amplifier and the first optical receiving unit, calculates a second necessary signal intensity that is a signal intensity that the second optical signal included in the multiplexed signal output from the amplifier is required to have, based on the second predetermined value, insertion loss that occurs in the multiplexer, and transmission loss that occurs between the amplifier and the second optical receiving unit, calculates respective output signal intensities of the first optical signal and the second optical signal that are included in the multiplexed signal output from the amplifier so as to satisfy the first necessary signal intensity and the second necessary signal intensity, respectively, calculates respective input signal intensities of the first optical signal and the second optical signal that are included in the multiplexed signal input to the amplifier, the input signal intensities being required to achieve the calculated output signal intensities, and calculates respective adjustment amounts for the signal intensities of the acquired first optical signal and second optical signal, based on a result of measuring the signal intensities of the acquired first optical signal and second optical signal and the calculated respective input signal intensities. ### Claim 7 A carrier monitoring device that adjusts respective signal intensities of a first optical signal and a second optical signal that are included in a multiplexed signal input to an amplifier for amplifying the first optical signal and the second optical signal, the first optical signal being an optical signal having a first wavelength that is obtained as a result of first frequency-multiplexed multi-channel signals being converted by means of FM batch conversion and that is to be transmitted to a first optical receiving unit, the second optical signal being an optical signal having a second wavelength different from the first wavelength that is obtained as a result of second frequency-multiplexed multi-channel signals being converted by means of FM batch conversion and that is to be transmitted to a second optical receiving unit, the carrier monitoring device comprising: a first acquisition unit for acquiring the first optical signal; a second acquisition unit for acquiring the second optical signal; a first measurement unit for measuring a signal intensity of the first optical signal acquired by the first acquisition unit; a second measurement unit for measuring a signal intensity of the second optical signal acquired by the second acquisition unit; an adjustment amount calculation unit for calculating respective adjustment amounts for the signal intensity of the first optical signal acquired by the first acquisition unit and the signal intensity of the second optical signal acquired by the second acquisition unit, based on a measurement result of the measurement performed by the first measurement unit and a measurement result of the measurement performed by the second measurement unit, such that the signal intensity of the first optical signal received by the first optical receiving unit is larger than or equal to a first predetermined value, the signal intensity of the second optical signal received by the second optical receiving unit is larger than or equal to a second predetermined value, and a signal intensity of the multiplexed signal output from the amplifier is larger than or equal to a third predetermined value; a signal intensity adjustment unit for adjusting the signal intensity of the first optical signal acquired by the first acquisition unit and the signal intensity of the second optical signal acquired by the second acquisition unit based on the respective adjustment amounts calculated by the adjustment amount calculation unit, and outputting the first optical signal and the second optical signal that have been subjected to the signal intensity adjustment; and a carrier monitoring function unit for obtaining an amount of frequency deviation of each carrier signal included in the first optical signal or the second optical signal, calculating a minimum optical sensitivity at the first optical receiving unit or the second optical receiving unit based on the amount of frequency deviation, and updating the first predetermined value or the second predetermined value based on the minimum optical sensitivity.