# US 2013/0154880 A1 · Digital beamforming for simultaneously mitigating weak and strong interference in a navigation system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154880 A1 - Document ID: US20130154880A1 - Status: Published application - Kind: A1 - Application number: 13/712,633 - Filed: 2012-12-12 - Published: 2013-06-20 - Earliest claimed: 2011-12-15 - Assignees: Northrop Grumman Guidance and Electronics Company, Inc. - Inventors: JEFF DICKMAN; MATHEW A. COSGROVE - Web page: https://patentgrep.com/patent/US20130154880A1 ## CPC - G01S 19/21: Interference related issues {; Issues related to cross-correlation, spoofing or other methods of denial of service} - G01S 19/215: {issues related to spoofing} - G01S 19/36: relating to the receiver frond end - 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 An adaptive cascaded electronic protection processing system for global navigation satellite system (GNSS) threat mitigation is provided. The system includes a precorrelation characterization component configured to provide at least one parameter characterizing a plurality of received signals. A correlator is configured to provide a plurality of correlation results, each representing one of the plurality of received signals. A spatial weight contribution component is configured to determine an optimal set of digital beam-forming weights via an optimization process according to the at least one parameter. A postcorrelation characterization component is configured to determine at least one constraint on the optimization process according to the plurality of correlation results. ## Claims ### Claim 1 An adaptive electronic protection system for a global navigation satellite system (GNSS) threat mitigation comprising: a precorrelation characterization component configured to provide at least one parameter characterizing a plurality of received signals; a correlator configured to provide a plurality of correlation results, each representing one of the plurality of received signals; a spatial weight computation component configured to determine an optimal set of digital beam-forming weights via an optimization process according to the at least one parameter; and a postcorrelation characterization component configured to determine at least one constraint on the optimization process according to the plurality of correlation results. ### Claim 2 (depends on 1) The adaptive electronic protection processing system of claim 1, wherein precorrelation characterization component provides a covariance matrix representing the plurality of received signals. ### Claim 3 (depends on 1) The adaptive electronic protection processing system of claim 1, the spatial weight computation component applying at least one constraint on the optimization process according to navigation data representing the position of at least one GNSS satellite. ### Claim 4 (depends on 1) The adaptive electronic protection processing system of claim 1, further comprising, for each received signal, a digital antenna electronics component configured to downconvert the received signal to an intermediate frequency, digitize the intermediate frequency signal into a stream of digital samples at an associated sampling rate, and downconvert the stream of digital samples to a baseband digital signal. ### Claim 5 (depends on 4) The adaptive electronic protection processing system of claim 4, further comprising, for each of the baseband digital signals, a temporal filter configured to provide a temporal cancelation of emitters to mitigate narrow-band jamming. ### Claim 6 (depends on 4) The adaptive electronic protection processing system of claim 4, a given temporal filter comprising: a shift register configured to apply a coarse delay to the baseband digital signal, the coarse delay comprising an integer increment of samples at the sampling rate; and a finite impulse response (FIR) filter, having adaptively selected weights, configured to apply a fine delay to the baseband digital signal. ### Claim 7 (depends on 6) The adaptive electronic protection processing system of claim 6, further comprising a precorrelation characterization component comprising a covariance estimation component to provide a signal covariance matrix representing the plurality of received signals and determine the adaptively selected weights for each FIR filter from at least the covariance estimation component. ### Claim 8 (depends on 7) The adaptive electronic protection processing system of claim 7, wherein a tap weight vector representing the adaptively selected weights for the FIR filters is calculated as the product of an inverse of the signal covariance matrix and an autocorrelation vector of the plurality of received signals. ### Claim 9 (depends on 1) The adaptive electronic protection processing system of claim 1, wherein the postcorrelation characterization component is configured to locate a spread-spectrum emitter, the at least one constraint on the optimization process determined by the spatial weight computation component comprising introducing a spatial null in a direction of the spread-spectrum emitter as an optimization constraint. ### Claim 10 (depends on 1) The adaptive electronic protection processing system of claim 1, the at least one constraint on the optimization process determined by the spatial weight computation component comprising an optimization constraint to compensate for carrier phase biases due to spatial beam-forming ### Claim 11 (depends on 1) The adaptive electronic protection processing system of claim 1, comprising: a set of multipliers configured to generate respective weighted correlation results from the plurality of correlation results; and a summation component configured to sum the weighted correlation results into a spatially filtered correlation result. ### Claim 12 (depends on 11) The adaptive electronic protection processing system of claim 11, further comprising a carrier phase repair component configured to compensate the spatially filtered correlation result for carrier phase biases due to spatial beam-forming. ### Claim 13 A method for adaptive processing in a navigation system comprising: applying temporal filtering to each of a plurality of input streams to provide a plurality of filtered input streams; generating a covariance matrix representing the plurality of input streams; generating a plurality of correlation results, each representing one of the plurality of filtered input streams; and calculating a beam-forming weight for each input stream from the covariance matrix and the plurality of correlation results. ### Claim 14 (depends on 13) The method of claim 13, wherein applying temporal filtering to each of a plurality of input streams comprises: applying a coarse delay to the input stream comprising an integer increment of samples at an associated sampling rate; and applying a finite impulse response (FIR) filter, having adaptively selected weights, to apply a fine delay to the input stream. ### Claim 15 (depends on 13) The method of claim 13, wherein calculating a beam-forming weight for each input stream from the covariance matrix and the plurality of correlation results comprises calculating the beam-forming weight for each input steam via an optimization process having at least one optimization constraint determined from the covariance matrix. ### Claim 16 (depends on 15) The method of claim 15, the optimization process comprising one of a minimum variance process, a minimum variance distortion-less response process, or adaptive filtering with bias constraints. ### Claim 17 (depends on 15) The method of claim 15, the optimization process being constrained by each of navigation data representing the position of a set of global navigation satellite system (GNSS) satellites and a location of an emitter that is not affiliated with the set of GNSS satellites. ### Claim 18 (depends on 13) The method of claim 13, further comprising: determining a spatially filtered correlation result from the plurality of correlation results and the beam-forming weight for each input stream; and compensating the spatially filtered correlation result for carrier phase biases due to spatial beam-forming. ### Claim 19 A adaptive electronic protection processing system for a global navigation satellite system (GNSS) threat mitigation comprising: a precorrelation characterization component configured to provide at least one parameter characterizing a plurality of received signals; a digital antenna electronics component configured to downconvert the received signal to an intermediate frequency, digitize the intermediate frequency signal into a stream of digital samples at an associated sampling rate, and downconvert the stream of digital samples to a baseband digital signal a temporal filter for each baseband digital signal configured to provide a temporal cancelation of emitters to mitigate narrow-band jamming; a correlator configured to provide a plurality of correlation results, each representing one of the plurality of baseband digital signals; a spatial weight computation component configured to determine an optimal set of digital beam-forming weights via an optimization process according to the at least one parameter; and a postcorrelation characterization component configured to determine at least one constraint on the optimization process according to the plurality of correlation results. ### Claim 20 (depends on 19) The adaptive electronic protection processing system of claim 19, the spatial weight computation component applying at least one constraint on the optimization process according to navigation data representing the position of at least one GNSS satellite and at least one constraint on the optimization process.