SYSTEM AND METHOD FOR LOCATING A POINT IN SPACE

• US 20130016011A1
• Filed: 02/20/2012
• Published: 01/17/2013
• Est. Priority Date: 07/13/2011
• Status: Active Grant

• Current Assignee: Sagrad, Inc
• Original Assignee: Sagrad, Inc
• Inventors: Harriman, Adam
• Granted Patent: US 9,182,469 B2
• Time in Patent Office: Days
• US Class Current: 342/372
• CPC Class Codes: G01S 3/023 Monitoring or calibrating
• CPC Class Codes: G01S 3/44 the adjustment being varied periodically or continuously until it is halted automatically when the desired condition is attained
• CPC Class Codes: H01Q 3/04 for varying one co-ordinate of the orientation
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence

Abstract

A method for locating a point in a first region based on receipt of a rf signal from the point. An antenna array is in the first region at a first position rotatable about an axis. A series of phase-array patterns is provided for implementation with the antenna array to provide measures of rf signal strength. Each pattern provides a plurality of reference values as a function of angle. A plurality of the phase-array patterns are used to acquire, in the first region, a plurality of rf signal strength values based on reception of the rf signal. A set of correlation values is determined where each value is a correlation between signal strength reference values and rf signal strength values acquired based on reception of the rf signal from the point. The correlation values identify a direction relative to the first position along which the point is located.

Claims

1. A method for locating a point in a first region based on receipt of a radio frequency (rf) signal that emanates from the point, comprising:

providing an antenna array in the first region at a first position and rotatable about a first axis;

providing a series of phase-array patterns for implementation with the antenna array to provide measures of rf signal strength;

using each phase-array pattern to provide a plurality of phase-array signal strength reference values as a function of angle of rotation about the first axis;

with the antenna array at the first position, further using a plurality of the phase-array patterns to acquire a plurality of rf signal strength values, each value based on reception of the rf signal that emanates from the point;

determining a set of correlation values where each value is a correlation between (i) signal strength reference values acquired with patterns in the series at one of the angles and (ii) the rf signal strength values acquired with the antenna array which are each based on reception of the rf signal that emanates from the point; and

using the correlation values to identify a direction relative to the first position along which the point is located.

2. The method of claim 1 wherein:

the step of using each phase-array pattern to provide a plurality of phase-array signal strength reference values as a function of angle of rotation about the first axis is performed in a second region different from the first region;

the antenna array is also rotated about a second axis in the second region to provide the signal strength reference values; and

for each combination of one in a plurality of angles of rotation about the first axis and one in a plurality of angles of rotation about the second axis, each in a set of signal strength reference values in the plurality of phase-array signal strength reference values is (i) based on a different one of the patterns and (ii) is acquired by measurement of a rf reference source signal with the antenna array over horizontal and vertical angles at a location different from where the antenna array is used to acquire signal strength values based on reception of the rf signal that emanates from the point.

3. The method of claim 1 wherein:

the step of using each phase-array pattern to provide the plurality of phase-array signal strength reference values as a function of angles of rotation about the first axis is performed in a second region different from the first region;

the signal strength reference values used for determining the set of correlation values are a subset of the plurality of phase-array signal strength reference values resulting from using a subset of the series of phase-array patterns to acquire with the antenna array the plurality of rf signal strength values which are based on the rf signal that emanates from the point in the first region, and

the subset of the series of phase-array patterns results from elimination of one or more patterns in said series of phase-array patterns.

4. The method of claim 3 wherein forming the subset of patterns results in a subset being formed of patterns which are relatively insensitive to reflections in the first region.

5. The method of claim 4 wherein elimination of patterns from the series to form the subset of the series improves accuracy of determining the pointing direction relative to finding the pointing direction with the entire series of phase-array patterns.

6. The method of claim 3 wherein the subset of patterns comprises patterns which exhibit less sensitivity to reflections occurring in the first region relative to an eliminated pattern when acquiring, in the first region, the plurality of signal strength reference values based on the rf signal that emanates from the point.

7. The method of claim 3 wherein the subset of patterns is formed of patterns which exhibit a greater sensitivity to changes in angle over a predefined range relative to an eliminated pattern.

8. The method of claim 7 wherein the predefined range includes a variation in angle about the first axis of plus or minus 0.5°

.

9. The method of claim 1 wherein each correlation value is based on a correlation between a signal strength reference value acquired for one of the patterns and an rf signal strength value acquired with the same one pattern and based on reception by the antenna array of the rf signal which emanates from the point.

10. The method of claim 1 wherein the array is also rotatable about a second axis and the step of using each phase array pattern to provide signal strength reference values includes acquiring the values as a function of rotation about the second axis.

11. A method for defining a set of receive patterns for use in a phase array antenna system to determine the direction of an object, comprising:

providing an rf source at a first location;

providing an antenna comprising a plurality of elements each arranged to separately receive an rf signal;

providing a first series of antenna receive patterns, each pattern defined by a set of phase shift values;

sequentially positioning the antenna at each in a set of first angles of orientation with respect to the first position of the source;

while the antenna is positioned at each angle of orientation, sequentially applying the sets of phase shift values to individually modify each rf signal received by each element and acquiring a first set of signal strength data for each receive pattern at each angle;

using the signal strength data to determine for each angle the relative sensitivity of each receive pattern to the rf signal;

identifying for each angle one or more receive patterns exhibiting relatively low signal strengths; and

defining a set of antenna receive patterns which is a first subset of the first series, which set (i) includes for each first angle of orientation at least one pattern having a relatively low signal strength and (ii) excludes other receive patterns present in the first series.

12. The method of claim 11 further including:

using members of the first subset of receive patterns, acquiring a second set of signal strength data from an rf source co-positioned with the object; and

comparing signal strength information derived from the first location for members of the first subset of receive patterns with signal strength data of the second set to determine the direction of the object.

13. The method of claim 11 wherein the step of comparing includes calculating correlations between signal strength information acquired at the first location with signal strength information acquired at the second location.

14. The method of claim 12 wherein the step of comparing signal strength information includes normalizing a set of signal strength values acquired from the first location and normalizing signal strength data of the second set.

15. The method of claim 11 wherein the first series of patterns includes over one million patterns and members of the subset are fewer than one hundred thousand patterns.

16. The method of claim 11 wherein the object is at a location different than the first location.

17. The method of claim 13 wherein the subset of the first series includes at least ten thousand patterns.

18. The method of claim 11 further including

providing an rf source, which may be the same source as, or a source different than, the first rf source, at a second position;

placing the antenna at each of a second number of angles (one angle) of orientation with respect to the second position, wherein the second angles include at least one of the first angles of orientation;

while the antenna is positioned at each angle in the second number of angles (one angle) of orientation with respect to the second position of orientation, acquiring a third set of signal strength data at the second location by applying sets of phase shift values for those receive patterns in the subset of the first series to individually modify each rf signal received by each element in accord with each of the receive patterns in the subset of the first series;

using the third set of signal strength data to identify one or more receive patterns exhibiting relatively low signal strengths at the second location; and

defining a second subset of antenna receive patterns which is a subset of the first subset of the first series, which second subset (i) includes for each in the first number of angles of orientation at least one pattern exhibiting a relatively low signal strength at the second location and (ii) excludes one or more receive patterns in the first subset.

19. The method of claim of 18 wherein the step of acquiring signal strength data from the object is performed at the second location using only members of the second subset of receive patterns.

20. The method of claim of 18 wherein the step of positioning the antenna at each of a second number of angles of orientation with respect to the second position only positions the antenna at one angle.

21. The method of claim 18 wherein the same rf source is used to acquire the first set of signal strength data and the third set of signal strength data.

22. The method of claim 18 wherein:

the object is positioned at the second location; and

the object and the second source are positioned different distances from the antenna.

25. A method for determining a pointing direction, comprising:

providing a set of phase array receive patterns each having a different response characteristic to a source as a function of angle;

receiving signal strength data from the source with each of the patterns;

making a comparison between the signal strength data from all of the patterns and each member in a group of data sets, wherein each member in the group of data sets comprises signal strength data acquired with the phase array receive patterns at one of a plurality of angle orientations with respect to a known source location; and

making a first determination of the pointing direction based on the comparison.

26. The method of claim 25 wherein the first determination identifies a zone based on the comparison, the method further including making at least a second determination of the pointing direction by orienting the set of receive patterns toward the zone and again receiving signal strength data from the source with each of the patterns.