# US 12,000,922 B2 · Determination of cardinal direction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,000,922 B2 - Document ID: US12000922B2 - Status: Granted - Kind: B2 - Application number: 17/342,273 - Filed: 2021-06-08 - Published: 2021-12-09 - Granted: 2024-06-04 - Earliest claimed: 2020-06-08 - Assignees: Elta Systems Ltd. - Applicants: Elta Systems Ltd. - Inventors: Josef Steinmetz - Web page: https://patentgrep.com/patent/US12000922B2 ## CPC - G01S 7/4026: {Antenna boresight} - G01S 13/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S13/46) - G01S 7/4091: {during normal radar operation} - G01S 13/867: {Combination of radar systems with cameras} - G01S 13/88: Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00) - 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 ## Abstract A method including: detecting that an aerial vehicle is located at a reference axis of a sensor, or at a predetermined or calculated angle of the reference axis of the sensor, the method further comprising, by a processor and memory circuitry: obtaining a given position Paerial of the aerial vehicle upon its detection at the reference axis of the sensor, or upon its detection at the predetermined or calculated angle of the reference axis of the sensor, and position Psensor of the sensor, and determining, based at least on Paerial and Psensor, a cardinal direction with respect to the reference axis. ## Claims ### Claim 1 A system including a processor and memory circuitry configured to: obtain a position Paerial of an aerial vehicle upon its detection at a reference axis of a sensor, or upon its detection at a predetermined or calculated angle of the reference axis of the sensor, and determine, based at least on Paerial and a position Psensor of the sensor, a cardinal direction with respect to the reference axis of the sensor. ### Claim 2 (depends on 1) The system of claim 1, including the sensor, wherein the sensor is configured to detect that the aerial vehicle is located at its reference axis, or at a predetermined or calculated angle of its reference axis. ### Claim 3 (depends on 1) The system of claim 1, wherein the cardinal direction is a north direction. ### Claim 4 (depends on 1) The system of claim 1, configured to: obtain a vector V′1 joining Paerial and Psensor and expressed in UTM coordinates, determine an orientation α of UTM north with respect to V′1, determine an orientation a of geographical north with respect to V′1, based on α, thereby determining orientation of the geographical north with respect to the reference axis. ### Claim 5 (depends on 1) The system of claim 1, configured to convert Paerial and Psensor into UTM coordinates, and determine a vector V′1 joining Psensor to Paerial in UTM coordinates. ### Claim 6 (depends on 1) The system of claim 1, comprising a camera having known spatial relationship relative to the sensor and usable to detect that the aerial vehicle is located at the reference axis of the sensor, or at a predetermined angle of the reference axis of the sensor. ### Claim 7 (depends on 6) The system of claim 6, configured to: obtain a vector V′1 joining Paerial and Psensor and expressed in UTM coordinates, determine an orientation α of UTM north with respect to V′1, determine an orientation σ of geographical north with respect to V′1, based on α, thereby determining orientation of the geographical north with respect to the reference axis. ### Claim 8 (depends on 7) The system of claim 7, configured to apply a correction to α or to σ to compensate a tilt between a light of sight of the camera and the reference axis of the sensor. ### Claim 9 (depends on 1) The system of claim 1, wherein the sensor is a radar or an antenna configured to: obtain at least one first received signal sensed by a first part of the radar or antenna, obtain at least one second received signal sensed by a second part of the radar or antenna, and detect that the aerial vehicle is located at the reference axis of the radar or antenna based on at least the first received signal and the second received signal. ### Claim 10 (depends on 9) The system of claim 9, configured to detect that the aerial vehicle is located at the reference axis of the radar or antenna based on a detection of an extremum of a function depending at least from the first received signal and the second received signal. ### Claim 11 (depends on 1) The system of claim 1, wherein the sensor is a radar or antenna, wherein the aerial vehicle is located in a blind zone of the radar or antenna, and wherein a signal transmitted by the aerial vehicle is delayed to simulate a virtual position of the aerial vehicle out of the blind zone. ### Claim 12 (depends on 1) The system of claim 1, wherein, for a system including a plurality of sensors including at least one first sensor and at least one second sensor, the system is configured to: detect that an aerial vehicle is located at a first reference axis of the first sensor, or at a first predetermined or calculated angle of the first reference axis of the sensor, obtain a position Paerial of the aerial vehicle upon its detection at the first reference axis of the first sensor, or at the first predetermined or calculated angle of the first reference axis of the first sensor, determine, at the position Paerial of the aerial vehicle, a deviation between the aerial vehicle and a second reference axis of the second sensor, determine, based at least on Paerial and a position Psensor,1 of the first sensor, a cardinal direction with respect to the first reference axis of the first sensor, determine, based at least on Paerial, a position Psensor,2 of the second sensor, and said deviation, the cardinal direction with respect to the second reference axis of the second sensor. ### Claim 13 (depends on 12) The system of claim 12, wherein the first sensor is an active sensor and the second sensor is a passive sensor. ### Claim 14 (depends on 1) The system of claim 1, wherein determination of the cardinal direction is obtainable without using an inertial system. ### Claim 15 (depends on 1) The system of claim 1, wherein the aerial vehicle is a UAV or a drone. ### Claim 16 (depends on 1) The system of claim 1, wherein the reference axis includes at least one of: a broadside direction of the sensor; a boresight direction of the sensor; a center phase of the sensor. ### Claim 17 (depends on 1) The system of claim 1, further configured to: determine data Pt1, . . . PtN informative of at least one of a relative angular position and a range of a given aerial vehicle with respect to the sensor at different instants of time, said given aerial vehicle corresponding to said aerial vehicle or to another aerial vehicle, obtain data P′t1, . . . P′tN informative of position of the given aerial vehicle at the different instants of time, and determine the position Psensor of the sensor based at least on Pt1, . . . PtN and P′t1, . . . PtN. ### Claim 18 A system comprising a processor and memory circuitry, wherein, for a plurality of sensors including at least one first sensor and at least one second sensor, the system is configured to: obtain a position Paerial of an aerial vehicle upon its detection at a first reference axis of the first sensor, or upon its detection at a first predetermined or calculated angle of the first reference axis of the first sensor, determine, at the position Paerial of the aerial vehicle, a deviation between the aerial vehicle and a second reference axis of the second sensor, determine, based at least on Paerial and a position Psensor,1 of the first sensor, a cardinal direction with respect to the first reference axis of the first sensor, determine, based at least on Paerial, a position Psensor,2 of the second sensor, and said deviation, the cardinal direction with respect to the second reference axis of the second sensor. ### Claim 19 A method including: detecting that an aerial vehicle is located at a reference axis of a sensor, or at a predetermined or calculated angle of the reference axis of the sensor, the method further comprising, by a processor and memory circuitry: obtaining a position Paerial of the aerial vehicle upon its detection at the reference axis of the sensor, or upon its detection at the predetermined or calculated angle of the reference axis of the sensor, and position Psensor of the sensor, and determining, based at least on Paerial and Psensor, a cardinal direction with respect to the reference axis. ### Claim 20 (depends on 19) The method of claim 19, further including: determining, by the sensor, data Pt1, . . . PtN informative of at least one of a relative angular position and a range of a given aerial vehicle with respect to the sensor at different instants of time, said given aerial vehicle corresponding to said aerial vehicle or to another aerial vehicle, the method further including, by a processor and memory circuitry: obtaining data P′t1, . . . P′tN informative of position of the given aerial vehicle at the different instants of time, and determining the position Psensor of the sensor based at least on Pt1, . . . PtN and P′t1, . . . P′tN. ### Claim 21 A non-transitory computer readable medium comprising instructions that, when executed by one or more processing circuitries, cause the one or more processing circuitries to perform: obtaining a position Paerial of an aerial vehicle upon its detection at a reference axis of a sensor, or upon its detection at a predetermined or calculated angle of the reference axis of the sensor, and determining, based at least on Paerial and a position Psensor of the sensor, a cardinal direction with respect to the reference axis of the sensor.