# US 2019/0170848 A1 · Systems and methods for direction finding using augmented spatial sample covariance matrices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170848 A1 - Document ID: US20190170848A1 - Status: Published application - Kind: A1 - Application number: 16/267,824 - Filed: 2019-02-05 - Published: 2019-06-06 - Earliest claimed: 2016-09-09 - Assignees: Raytheon Company - Applicants: Raytheon Company - Inventors: James M. Bowden - Web page: https://patentgrep.com/patent/US20190170848A1 ## CPC - G01S 3/043: {Receivers} - G01S 3/14: Systems for determining direction or deviation from predetermined direction {(aerial arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00; combinations of different interacting aerial units for giving a desired directional characteristic H01Q21/29; aerials or aerial systems providing at least two radiation patterns H01Q25/00)} - G01S 3/48: the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured - G01S 3/74: Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals (systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14) - G01S 11/02: using radio waves (G01S19/00 takes precedence) - 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 In an array antenna having a plurality of subarrays, a direction finding system and technique includes receiving signals at an array antenna and capturing data with a plurality of groups of subarrays. Each group of subarrays may capture data during a selected one of a plurality of different dwell times. The method further includes generating a plurality of dwell spatial sample covariance matrices (SCMs) using data corresponding to one or more of the plurality of groups of subarrays and combining the plurality of dwell spatial SCMs in complex form to generate an aggregate covariance matrix (ACM). The ACM may then be used in subsequent processing with MINDIST technique to estimate a direction of a received signal based on the combined data. ## Claims ### Claim 1 A system comprising: a plurality of subarrays, each of the subarrays having an output port; a radio frequency (RF) receiver having one or more receiver channels, wherein the number of subarrays is greater than the number receiver channels; and a switch network having a plurality of input ports with each input port coupled to an output of one or more respective ones of said plurality of subarrays and having output ports with each switch output coupled to an input of respective one of the one or more receiver channels, said switch network operable to switch between different groups of subarrays at different dwell times such that at least one group of subarrays is configured to provide signals to the receiver channels; a direction finding processor coupled to receive signals from said RF receiver during a selected one of a plurality of dwell times. ### Claim 2 (depends on 1) The system of claim 1, wherein said receiver is configured to simultaneously provide signals to said DF processor of subarrays is active and at least one array element in each of the groups of subarrays is inactive. ### Claim 3 (depends on 1) The system of claim 1, wherein the switch matrix comprises a plurality of stages and each of the plurality of stages includes two or more switches. ### Claim 4 (depends on 1) The system of claim 1, wherein each of the plurality of subarrays is coupled to an input of said switch network. ### Claim 5 (depends on 1) The system of claim 1, wherein at least one subarray of the group of subarrays is coupled directly to a receiver channel. ### Claim 6 (depends on 1) The system of claim 1, wherein each of the plurality of subarrays comprise one or more antenna elements coupled directly to the direction finding module. ### Claim 7 (depends on 1) The system of claim 1, wherein the direction finding module comprises: a spatial sample covariance matrix (SCM) module to receive the data and generate one or more dwell spatial sample covariance matrices (SCMs) and an aggregate covariance matrix using the data; a p-table module to generate a table having components as a function of frequency and angle measurements; a principal component module coupled to the SCM module and the p-table module, wherein the principal component module generates a principal component table having one or more principal components sorted by the frequency and angle measurements; a distance measurement module coupled to the principal component module, wherein the distance measurement module calculates a distance from a test point to each entry in the principal component table; and a minimum distance module coupled to the distance measurement module, wherein the minimum distance measurement module determines a minimum distance point based on the calculated distances from the test point to each entry in the principal component table. ### Claim 8 (depends on 1) The system of claim 1, wherein the switch network is further configured to select groups of subarrays from among the plurality of groups of subarrays with which to receive signals. ### Claim 9 (depends on 1) The system of claim 1, wherein each of the selected groups of subarrays are configured to receive signals during a corresponding one of a plurality of dwell times. ### Claim 10 (depends on 1) The system of claim 1, wherein at each of the plurality of dwell times, the switch network is further configured to simultaneously couple respective ones of a selected group of subarrays to respective ones of the one or more receiver channels. ### Claim 11 (depends on 7) The system of claim 7, wherein the SCM module generates the aggregate covariance matrix by combining the one or more dwell spatial SCMs in complex form. ### Claim 12 (depends on 11) The system of claim 11, wherein the minimum distance module is further configured to use values from the aggregate covariance matrix to generate a DF output signal indicative of a direction of a signal received by at least some of the selected groups of subarrays. ### Claim 13 (depends on 12) The system of claim 12, wherein the principal component module is configured to use values from the aggregate covariance matrix to pre-compute the principal component table. ### Claim 14 (depends on 13) The system of claim 13, wherein the distance measurement module is configured to form the test point by extracting the one or more principal components as complex phases from the aggregate covariance matrix. ### Claim 15 (depends on 14) The system of claim 14, wherein the minimum distance point corresponds to a direction of the received signals. ### Claim 16 (depends on 15) The system of claim 15, wherein the p-table module is configured to determine vector data for each of the plurality of array elements, wherein the vector data includes an angle and a frequency measurement. ### Claim 17 (depends on 16) The system of claim 16, wherein the p-table module is configured to identify a phase difference between each of the elements in the aggregated covariance matrix using angle measurements.