# US 8,542,364 B1 · System to reduce gyroscopic errors with limited power supply quality in a fiber optic gyroscope > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,364 B1 - Document ID: US8542364B1 - Status: Granted - Kind: B1 - Application number: 12/640,931 - Filed: 2009-12-17 - Granted: 2013-09-24 - Earliest claimed: 2009-12-17 - Assignees: Honeywell International Inc. - Applicants: Gregory W Keith; Derek Mead; Douglas E. Smith; Norman Gerard Tarleton - Inventors: Gregory W Keith; Derek Mead; Douglas E. Smith; Norman Gerard Tarleton - Web page: https://patentgrep.com/patent/US8542364B1 ## CPC - G01C 19/726: {Phase nulling gyrometers, i.e. compensating the Sagnac phase shift in a closed loop system} - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) ## Abstract A fiber optic gyroscope includes a light source, an optical coupler in optical communication with the light source, with the optical coupler configured to receive an optical signal from the light source, an optical modulator in optical communication with the optical coupler, and a fiber optic coil in optical communication with the optical modulator. A demodulator is configured to receive an optical signal from the optical coupler and convert the optical signal to an electrical signal. A loop closure electronics module is configured to receive the electrical signal from the demodulator. A bias modulator is responsive to an output from the loop closure electronics module and is configured to output a modulation signal to the optical modulator. A first crosstalk filter network is operatively coupled to the demodulator, and a second crosstalk filter network is operatively coupled to the bias modulator. ## Claims ### Claim 1 A fiber optic gyroscope, comprising: a light source; an optical coupler in optical communication with the light source and configured to receive an optical signal from the light source; an optical modulator in optical communication with the optical coupler; a fiber optic coil in optical communication with the optical modulator; a demodulator configured to receive an optical signal from the optical coupler and convert the optical signal to an electrical signal; a loop closure electronics module configured to receive the electrical signal from the demodulator; a bias modulator responsive to an output from the loop closure electronics module and configured to output a modulation signal to the optical modulator; a first crosstalk filter network operatively coupled to the demodulator; and a second crosstalk filter network operatively coupled to the bias modulator. ### Claim 2 (depends on 1) The fiber optic gyroscope of claim 1, wherein the light source comprises a laser. ### Claim 3 (depends on 1) The fiber optic gyroscope of claim 1, wherein the optical modulator comprises an integrated optical chip. ### Claim 4 (depends on 1) The fiber optic gyroscope of claim 1, wherein the first crosstalk filter network comprises a first pair of common mode and differential mode filter networks. ### Claim 5 (depends on 1) The fiber optic gyroscope of claim 1, wherein second crosstalk filter network comprises a second pair of common mode and differential mode filter networks. ### Claim 6 (depends on 1) The fiber optic gyroscope of claim 1, further comprising a first power supply that provides a positive voltage to the first and second crosstalk filter networks. ### Claim 7 (depends on 6) The fiber optic gyroscope of claim 6, further comprising a second power supply that provides a negative voltage to the first and second crosstalk filter networks. ### Claim 8 (depends on 1) The fiber optic gyroscope of claim 1, wherein the first and second crosstalk filter networks are connected to a common ground reference. ### Claim 9 (depends on 1) The fiber optic gyroscope of claim 1, further comprising a sampling clock generator operatively coupled to the loop closure electronics module. ### Claim 10 (depends on 9) The fiber optic gyroscope of claim 9, further comprising a tunable bias modulation clock generator operatively coupled to the bias modulator. ### Claim 11 (depends on 1) The fiber optic gyroscope of claim 1, wherein the fiber optic gyroscope is a interferometric fiber optic gyroscope. ### Claim 12 (depends on 1) The fiber optic gyroscope of claim 1, wherein the first and second crosstalk filter networks include at least one filter circuit comprising: a first input line coupled to a first capacitor and a common mode choke; a second input line coupled to the first capacitor and the common mode choke; a first output line from the common mode choke coupled to a second capacitor; and a second output line from the common mode choke coupled to the second capacitor. ### Claim 13 (depends on 1) The fiber optic gyroscope of claim 1, wherein the first and second crosstalk filter networks include at least one filter circuit comprising: a first input line coupled to a first capacitor and common mode choke; a second input line coupled to the first capacitor and the common mode choke; a first output line from the common mode choke coupled to a first inductor; a second output line from the common mode choke coupled to a second inductor; a first output line from the first inductor coupled to a second capacitor and a third capacitor; and a second output line from the second inductor coupled to the second capacitor and a resistor, wherein the third capacitor is coupled to the resistor. ### Claim 14 (depends on 1) The fiber optic gyroscope of claim 1, wherein the first and second crosstalk filter networks include at least one filter circuit comprising: a first input line coupled to a first capacitor and a common mode choke; a second input line coupled to the first capacitor and the common mode choke; a first output line from the common mode choke coupled to a first inductor; a second output line from the common mode choke coupled to a second inductor; a first output line from the first inductor coupled to a first resistor; a second output line from the second inductor coupled to a second resistor; a first output line from the first resistor coupled to a second capacitor and a third capacitor; and a second output line from the second resistor coupled to the second capacitor and a third resistor, wherein the third capacitor is coupled to the third resistor. ### Claim 15 (depends on 1) The fiber optic gyroscope of claim 1, wherein the first and second crosstalk filter networks each comprise at least one single stage choke circuit for a floating ground. ### Claim 16 (depends on 1) The fiber optic gyroscope of claim 1, wherein the first and second crosstalk filter networks each comprise at least one dual stage choke circuit for a floating ground. ### Claim 17 An interferometric fiber optic gyroscope, comprising: a laser light source; an optical coupler in optical communication with the laser light source and configured to receive an optical signal from the laser light source; an integrated optical chip in optical communication with the optical coupler; a fiber optic coil in optical communication with the integrated optical chip; a demodulator configured to receive an optical signal from the optical coupler and convert the optical signal to an electrical signal; a loop closure electronics module configured to receive the electrical signal from the demodulator; a bias modulator responsive to an output from the loop closure electronics module and configured to output a modulation signal to the integrated optical chip; a first crosstalk filter network operatively coupled to the demodulator, the first crosstalk filter network comprising a first pair of common mode and differential mode filter networks; and a second crosstalk filter network operatively coupled to the bias modulator, the second crosstalk filter network comprising a second pair of common mode and differential mode filter networks. ### Claim 18 (depends on 17) The fiber optic gyroscope of claim 17, wherein the first and second crosstalk filter networks are connected to a common ground reference. ### Claim 19 (depends on 17) The fiber optic gyroscope of claim 17, wherein the first and second crosstalk filter networks each comprise at least one single stage choke circuit for a floating ground. ### Claim 20 (depends on 17) The fiber optic gyroscope of claim 17, wherein the first and second crosstalk filter networks each comprise at least one dual stage choke circuit for a floating ground.