# US 2020/0403701 A1 · Equalizer device, communication system, and equalization method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0403701 A1 - Document ID: US20200403701A1 - Status: Published application - Kind: A1 - Application number: 16/975,544 - Filed: 2019-02-20 - Published: 2020-12-24 - Earliest claimed: 2018-02-27 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Masao TANEHASHI - Web page: https://patentgrep.com/patent/US20200403701A1 ## CPC - H04B 10/25073: {using spectral equalisation, e.g. spectral filtering} - H04B 10/2941: {using an equalising unit, e.g. a filter (H04B10/296 takes precedence)} - H04B 10/294: in a multiwavelength system, e.g. gain equalisation - H04L 25/03878: {Line equalisers; line build-out devices} - H04Q 11/0005: {Switch and router aspects} - H04Q 2011/0016: {using wavelength multiplexing or demultiplexing} - H04Q 2011/0035: {using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical} - H04Q 2011/0058: {Crossbar; Matrix} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) ## Abstract An equalizer device includes: an optical matrix switch including a first terminal group including at least two first terminals and a second terminal group including at least two second terminals; an equalizer group including at least two equalizers, an input end of each of the equalizers being connected to one of the second terminals included in the second terminal group, and an output end of each of the equalizers being connected to one of the first terminals included in the first terminal group; a variable attenuator being connected to the second terminal in a last stage included in the second terminal group and attenuating an input optical signal; and controller that changes a connection state between the first terminal and the second terminal, and sets an amount of attenuation in the variable attenuator. ## Claims ### Claim 1 An equalizer device comprising: an optical matrix switch including a first terminal group including at least two first terminals and a second terminal group including at least two second terminals; an equalizer group including at least two equalizers, an input end of each of the equalizers being connected to one of the second terminals included in the second terminal group, and an output end of each of the equalizers being connected to one of the first terminals included in the first terminal group; a variable attenuator being connected to the second terminal in a last stage included in the second terminal group and attenuating an input optical signal; and controller that changes a connection state between the first terminal and the second terminal, and sets an amount of attenuation in the variable attenuator. ### Claim 2 (depends on 1) The equalizer device according to claim 1, wherein each of the equalizers included in the equalizer group adjusts a tilt level of an optical signal input from the input end and outputs the tilt-level-adjusted optical signal from the output end. ### Claim 3 (depends on 1) The equalizer device according to claim 1, wherein the controller is configured to set an amount of attenuation in the variable attenuator according to an amount of loss of an optical signal externally input to the optical matrix switch. ### Claim 4 (depends on 3) The equalizer device according to claim 3, wherein the controller is configured to set an amount of attenuation in the variable attenuator, based on a number of the equalizer passing an optical signal. ### Claim 5 (depends on 4) The equalizer device according to claim 4, wherein the controller is configured to set a larger amount of attenuation in the variable attenuator as a number of the equalizer passing an optical signal decreases. ### Claim 6 (depends on 1) The equalizer device according to claim 1, wherein the controller is configured to: include a setting table summarizing a connection state set to the first terminal and the second terminal group in association with a tilt level of compensation, and an attenuation setting set to the variable attenuator according to an amount of loss of an externally input optical input signal; change a connection state between the first terminal included in the first terminal group and the second terminal included in the second terminal group according to a tilt level set to the optical input signal; and set an amount of attenuation in the variable attenuator, based on the attenuation setting set in association with a tilt level set to the optical input signal. ### Claim 7 (depends on 1) A communication system comprising: the equalizer device according to claim 1; at least two repeaters; and an optical cable connecting the repeater to the equalizer device. ### Claim 8 (depends on 7) The communication system according to claim 7, wherein the equalizer device inputs an optical signal output from the repeater in a previous stage as an optical input signal, compensates for a tilt level of the input optical input signal, attenuates a signal strength of a tilt-level-compensated optical signal in such a way as to bring the signal strength close to a signal strength of the optical input signal, and outputs a signal-strength-attenuated optical signal to the repeater in a subsequent stage as an optical output signal. ### Claim 9 An equalization method in an equalizer device including: an optical matrix switch including a first terminal group including at least two first terminals and a second terminal group including at least two second terminals; an equalizer group including at least two equalizers, an input end of each of the equalizers being connected to one of the second terminals included in the second terminal group, and an output end of each of the equalizer being connected to one of the first terminals included in the first terminal group; and a variable attenuator being connected to one of the second terminals included in the second terminal group and attenuating an optical signal input to the optical matrix switch according to an amount of loss of the optical signal, the equalization method comprising changing a connection state between the first terminal and the second terminal, compensating for a tilt level of an externally input optical signal by setting an amount of attenuation by the variable attenuator according to an amount of loss of an optical signal input to the optical matrix switch and outputting a tilt-level-compensated optical signal as an optical output signal. ### Claim 10 (depends on 9) The equalization method according to claim 9, further comprising setting an amount of attenuation in the variable attenuator according to an amount of loss of an optical signal externally input to the optical matrix switch.