# US 6,590,520 B1 · Method and system for determining air turbulence using bi-static measurements > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,590,520 B1 - Document ID: US6590520B1 - Status: Granted - Kind: B1 - Application number: 10/067,154 - Filed: 2002-02-04 - Granted: 2003-07-08 - Earliest claimed: 2002-02-04 - Assignees: Lockheed Martin Corporation - Inventors: Daniel Walter Steele; Joseph L. Chovan - Web page: https://patentgrep.com/patent/US6590520B1 ## CPC - G01S 13/953: {mounted on aircraft} - G01S 3/48: the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured - G01S 13/003: {Bistatic radar systems; Multistatic radar systems} - G01S 13/87: Combinations of radar systems, e.g. primary radar and secondary radar - Y02A 90/10: Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE ## Abstract A method and system for determining atmospheric disturbances or turbulence is disclosed. The system includes a plurality of sensor arrays, including at least one sensor element, distributed in a predetermined manner. Each of the sensor elements is in communication with a corresponding receiving system that is operable to receive and process energy received from the aircraft. A determination is then made regarding air turbulence by determining a rate of change of signal phase among selected sets of signals received at the receiving systems. A turbulence map is then determined from the determined rate of change of the phase and the angle of the received signal. When the rate of phase change exceeds known levels an indication of turbulence is made. ## Claims ### Claim 1 A system for determining atmospheric disturbance that may exist in front of an aircraft comprising: a plurality of sensor arrays, each array containing at least one sensor element, arranged in a predetermined pattern and concurrently receiving at least one signal; a receiving system in communication with a corresponding one of said at least one sensor element in each of said plurality of sensor arrays, said receiving system operable to isolate a same signal from said at least one received signal in each of said plurality of sensor arrays; means for determining a phase value for each of said same signals; means for determining a rate of phase change for selected subsets of said same signals; means for indicating turbulence when said rate of phase change exceeds a known threshold associated with selected subsets of said same received signals. ### Claim 2 (depends on 1) The system as recited in claim 1 further comprising means for mapping each of said turbulence indications, wherein said turbulence indications are associated with a corresponding signal angle of arrival. ### Claim 3 (depends on 1) The system as recited in claim 1 wherein said same signal is selected from the group comprising: IFF, altitude transponder, navigation transponder, VHF radio, UHF radio, FLIR, ground based RADAR, weather RADAR, ultraviolet, visible, infrared. ### Claim 4 (depends on 1) The system as recited in claim 1 wherein said plurality of sensor arrays are located forward of said aircraft direction of travel. ### Claim 5 (depends on 1) The system as recited in claim 1 wherein said plurality of sensor arrays are located aft of said aircraft direction of travel. ### Claim 6 (depends on 1) The system as recited in claim 1 wherein said subsets are selected from at least two sensor arrays. ### Claim 7 (depends on 1) The system as recited in claim 1 wherein said predetermined pattern is selected from the group comprising: circular, rectangular, linear, square, star, perpendicular, parallel. ### Claim 8 (depends on 1) The system as recited in claim 1 wherein said rate of phase change is determined as a difference in instantaneous phase differences among at least two same signals at at least two known times. ### Claim 9 (depends on 1) The system as recited in claim 1 wherein said rate of phase change is determined as a difference in phase differences among at least two same signals over at at least two known periods. ### Claim 10 (depends on 9) The system as recited in claim 9 wherein said phase difference is an average of phase differences in each of said at least two known periods. ### Claim 11 (depends on 9) The system as recited in claim 9 wherein said phase difference is a weighted average of phase differences in each of said at least two known periods. ### Claim 12 (depends on 9) The system as recited in claim 9 wherein said phase difference is a polynomial function representative of phase differences in each of said at least two known periods. ### Claim 13 (depends on 12) The system as recited in claim 12 wherein said polynomial function is determined using a minimum least square error. ### Claim 14 (depends on 1) The system as recited in claim 1 wherein said at least one sensor element is predeterminedly positioned within a corresponding sensor array. ### Claim 15 (depends on 14) The system as recited in claim 14 wherein said at least one sensor element is positioned with a corresponding sensor array to provide unambiguous angle of arrival information. ### Claim 16 (depends on 14) The system as recited in claim 14 wherein said at least one sensor element is positioned in accordance with interferometric equations. ### Claim 17 (depends on 1) The system as recited in claim 1 further comprising: means for determining an angle of arrival of said same signal received at a corresponding sensor array. ### Claim 18 (depends on 1) The system as recited in claim 1 wherein said sensor arrays are substantially ground based. ### Claim 19 (depends on 1) The system as recited in claim 1 wherein said sensor arrays are located on said aircraft. ### Claim 20 (depends on 19) The system as recited in claim 19 wherein said sensor arrays are located to detect said received signal. ### Claim 21 A method for determining air turbulence which can undesirably affect the operation of an aircraft subjected to said turbulence comprising the steps of: receiving a signal at a predetermined frequency in an area where said turbulence is expected; detecting a phase change in said received signal due to turbulence; comparing said detected phase change with a threshold value; and indicating the presence of said turbulence when said detected phase change exceeds said threshold value. ### Claim 22 (depends on 21) The method as recited in claim 21 wherein the step of receiving further comprises: employing at a plurality of sensor arrays, each array containing at least one sensor element, arranged in a predetermined pattern for concurrently receiving said predetermined frequency signal; processing said received signal at a receiving system corresponding to each of said at least one sensor elements; determining a phase value for each received signal; determining a rate of phase change for selected subsets of said received signals. ### Claim 23 (depends on 21) The system as recited in claim 21 further comprising the step of: mapping said turbulence indications, wherein said turbulence indications are associated with a corresponding signal angle of arrival. ### Claim 24 (depends on 21) The method as recited in claim 21 wherein said received signal is selected from the group comprising: IFF, altitude transponder, navigation transponder, VHF radio, UHF radio, FLIR, ground based RADAR, weather RADAR, ultraviolet, visible, infrared. ### Claim 25 (depends on 22) The method as recited in claim 22 wherein said plurality of sensor arrays are located forward of said aircraft direction of travel. ### Claim 26 (depends on 22) The method as recited in claim 22 wherein said plurality of sensor arrays are located aft of said aircraft direction of travel. ### Claim 27 (depends on 22) The method as recited in claim 22 wherein said subsets are selected from at least two sensor arrays. ### Claim 28 (depends on 22) The method as recited in claim 22 wherein said predetermined pattern is selected from the group comprising: circular, rectangular, linear, square, star, perpendicular, parallel. ### Claim 29 (depends on 21) The method as recited in claim 21 wherein said rate of change is determined as a difference in instantaneous phase differences among at least two received signals at at least two known times. ### Claim 30 (depends on 21) The method as recited in claim 21 wherein said rate of change is determined as a difference in phase differences among at least two same received signals over at at least two known periods. ### Claim 31 (depends on 30) The method as recited in claim 30 wherein said phase difference is an average of phase differences in each of said at least two known periods. ### Claim 32 (depends on 30) The method as recited in claim 30 wherein said phase differences are a weighted average of phase differences in each of said at least two known periods. ### Claim 33 (depends on 30) The method as recited in claim 30 wherein said phase difference is a polynomial function representative of phase differences in each of said at least two known periods. ### Claim 34 (depends on 33) The method as recited in claim 33 wherein said polynomial function is determined using a minimum least square error. ### Claim 35 (depends on 22) The method as recited in claim 22 wherein said at least one sensor element is predeterminedly positioned within a corresponding sensor array. ### Claim 36 (depends on 35) The method as recited in claim 35 wherein said at least one sensor element is positioned to provide unambiguous angle of arrival information. ### Claim 37 (depends on 35) The method as recited in claim 35 wherein said at least one sensor element is positioned in accordance with interferometric equations. ### Claim 38 (depends on 22) The method as recited in claim 22 further comprising the step of: determining an angle of arrival of each of said received signal received at a corresponding sensor array. ### Claim 39 (depends on 22) The method as recited in claim 22 wherein said sensor arrays are substantially ground based. ### Claim 40 (depends on 22) The method as recited in claim 22 wherein said sensor arrays are located on said aircraft. ### Claim 41 (depends on 40) The method as recited in claim 40 wherein said sensor arrays are located to detect said received signal.