Direction finding system device and method

• US 8,988,283 B2
• Filed: 03/16/2011
• Issued: 03/24/2015
• Est. Priority Date: 03/17/2010
• Status: Active Grant

• Current Assignee: HISEP Technology, Ltd.
• Original Assignee: HISEP Technology, Ltd.
• Inventors: Erad, Yariv, Vered, Uri, Vered, Gal, Erad, Menachem
• Primary Examiner(s): LIU, HARRY K
• Application Number:
  US13/634,736
• Publication Number:
  US 20130002489A1
• Time in Patent Office: 1,469 Days
• Field of Search: 342/432, 342/434, 342/437, 342/443, 342/417
• US Class Current: 342/432
• CPC Class Codes: G01S 3/20 derived by sampling signal received by an antenna system having periodically-varied orientation of directivity characteristic
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence

Abstract

The present invention relates to a method for determining the direction to a target by a direction finder, which comprises: predefining a direction axis as a 0° direction; first and second pair of antennas arranged such that a first line connecting between the first pair of antennae defines a 0°-180° axis parallel to said direction axis, and a second line connecting said second pair of antennas defines a 90°-270° axis perpendicular to said direction axis; generating a 0° antenna pattern and establishing a wireless communication between the direction finder and said target; attenuating the wireless communication signal until lost and recording the attenuation value; generating a 180° antenna pattern using said first pair of antennas, and establishing a wireless communication between the direction finder and said target; attenuating the wireless communication signal until lost, and recording the attenuation value and concluding a true direction to the target.

Claims

1. Method for determining the direction to a target by a direction finder, which comprises:

a. predefining a direction axis on a plane of the direction finder as a 0°

direction;

b. providing on said plane of the direction finder a first pair and a second pair of antennas, said first and second pairs of antennas are arranged in such a configuration that a first line connecting between the two antennas of the first pair defines a 0°

-180°

axis which is parallel to said direction axis of the direction finder, and a second line connecting between the two antennas of said second pair of antennas defines a 90°

-270°

axis which is perpendicular to said direction axis of the direction finder;

c. generating a 0°

antenna pattern A using said first pair of antennas, and establishing a wireless communication between the direction finder and said target;

d. attenuating the wireless communication signal between the direction finder and said target until the wireless communication is lost, and recording the attenuation value R_A which corresponds to said loss of wireless communication;

e. generating a 180°

antenna pattern B using said first pair of antennas, and establishing a wireless communication between the direction finder and said target;

f. attenuating the wireless communication signal between the direction finder and said target until the wireless communication is lost, and recording the attenuation value N_B which corresponds to said loss of wireless communication;

g. determining from the relation between attenuations R_A and N_B and from the respective antenna patterns A and B one or more possible directions to the target;

h. repeating steps (c)-(g) for antenna patterns C and D in 90° and

270°

respectively while using said second pair of antennas, and determining from the respective antenna patterns C and D and from the relation between attenuations R_C and N_D one or more additional possible directions to the target; and

i. correlating between all the directions as obtained in steps (g) and (h) and concluding a true direction φ

to the target.

2. Method according to claim 1, wherein each of the antenna patterns has a form of a cardioid.

3. Method according to claim 1, wherein said two pairs of antennas are four antennas that are arranged in a rhombus configuration.

4. Method according to claim 1, wherein said two pairs of antennas are three antennas that are arranged in a right isosceles triangle, while one of the antennas is common to the two pairs of antennas.

5. Method according to claim 1, wherein a loss of wireless communication is a loss of handshake between the direction finder and the target.

6. Method according to claim 1, wherein the communication signal which is attenuated up to a point of loss of communication is the received signal or the transmitted signal.

7. Method according to claim 1 for a 2D direction finding, wherein said plane of the direction finder is maintained essentially horizontally during said direction finding.

8. Method according to claim 1, for further finding the elevation angle between the direction finder and the target, which further comprises the step of:

while maintaining said plane of the direction finder essentially vertical, performing steps (c)-(g), resulting in determination of one or more elevation angles θ

to the target.

9. Method according to claim 8, further comprising a verification procedure for the determined elevation angle, which comprises repeating said steps (c)-(g) while using another pair of antennas, and correlation of the results to the previous ones to obtain a true elevation angle.

10. Method according to claim 1 for further determining the distance from the target, wherein the distance is determined using the round trip time of the signal between the direction finder and the target, the speed of light, and the processing times of the direction finder and the target.

11. Method according to claim 8 for compensating a case where the device is not held perfectly vertical, wherein the direction finder further comprises a tilt sensor for measuring the tilt angle δ

of the direction finder relative to an axis vertical to the horizon, and subtracting this tilt angle from the elevation angle θ

to obtain a true elevation angle.

12. Method according to claim 7 for compensating a case where the device is not held perfectly horizontal, wherein the direction finder further comprises a tilt sensor for measuring the tilt angle δ

of the direction finder relative to an axis vertical to the horizon, and compensating respectively the direction φ

to obtain a true direction angle φ

to the target.

13. Method according to claim 11, wherein the measured angle δ

serves for the device as an indication to perform a 2D direction measurement when δ

is essentially 0°

, an elevation angle measurement when δ

is essentially 90°

, or both a 2D measurement and an elevation angle measurement when δ

is essentially 45°

thereby performing a 3D measurement.

14. Method according to claim 1 wherein each determination of the possible directions to the target based on the respective attenuations and on the antenna patterns is performed using one or more equations or one or more look up tables.

15. Method according to claim 8 wherein each determination of the possible elevation of the target with respect to the direction finder based on the respective attenuations and on the antenna patterns is performed using one or more equations or one or more look up tables.

16. Method according to claim 14, wherein the look up tables or equations also comprise correction factors to compensate for one or more of:

a. a specific pair of antennas in use and the characteristics of each antenna;

b. a 2D or 3D mode of operation, and the tilt angle of holding the device;

c. an operating frequency of the communication;

d. an antenna type in use; and

e. effect of the manner of holding the direction finder by the user hands on the antennas patterns.

17. Method according to claim 10, wherein the targets 2D or 3D locations are displayed in a radar-alike manner.

18. Method according to claim 17, which includes requesting by the direction finder and receiving from the target additional information relating to the identity of the target, its status, its type, or its characteristics, and displaying to the user at least a portion thereof.

19. Method according to claim 18, further comprising filtering from the display at least some of the targets, based on targets type, status, location, range from the direction finder or a target, characteristics of targets, angular sector, or a combination thereof.

20. Method according to claim 18 for use in monitoring of a child, wherein the target is attached to a child.

21. Method according to claim 18, wherein the target is attached to a product or is located at a specific department of a store, and wherein the direction to the product or said specific department respectively is determined and displayed.

22. Method according to claim 18, wherein one or more of the targets are defined as Landmarks or Marks.

23. Method according to claim 18, wherein relative distances, elevations, and directions between targets are calculated and displayed.

24. Method according to claim 17, which is performed repeatedly for the purpose of navigation.

25. Method according to claim 24, wherein when both the direction finder and the target are in movement, an estimated meeting location between them is calculated and displayed at the DF.

26. Method according to claim 1, which further comprises a step of transferring by the direction finder data to the target, or performing operation at the DF based on the results of the direction finding.

27. Method according to claim 26, for operating a music system, wherein at a first stage targets are located and assigned a speaker name, and at a second stage music data are transferred respectively to each of the targets.

28. A direction finder for determining the direction to a target, which comprises:

a. a first pair and a second pair of antennas, said first and second pairs of antennas are arranged on a plane of the direction finder in such a configuration that a first line connecting between the two antennas of the first pair defines a 0°

-180°

axis which is parallel to said direction axis of the direction finder, and a second line connecting between the two antennas of said second pair of antennas defines a 90°

-270°

axis which is perpendicular to said direction axis of the direction finder;

b. a wireless communication unit for establishing communication with a target via a wireless communication signal;

c. a controlled attenuator for attenuating said wireless communication signal;

d. a hybrid junction for enabling wireless communication of said signal in a selected antenna pattern each time via one of said pairs of antennas; and

e. a processing unit for;

e.1. switching said hybrid junction to generate and transmit a 0°

antenna pattern A through the first pair of antennas, attenuating the signal until the wireless communication is lost, and recording the attenuation value which corresponds to said loss of wireless communication as an R_A attenuation value;

e.2. switching at the hybrid junction to generate a 180°

antenna pattern B through the first pair of antennas, attenuating the signal until the wireless communication is lost, and recording the attenuation value which corresponds to said loss of wireless communication as an N_B attenuation value;

e.3. using one or more equations or look up tables, determining from the difference R_A−

N_B, one or more possible directions to the target;

e.4. repeating steps (e.1)-(e.3) while transmitting antenna patterns C and D in 90° and

270°

respectively through the second pair of antennas, and determining from the antenna patterns C and D respectively and from the relation between attenuations R_C and N_D one or more additional possible directions to the target; and

e.5. correlating between all the directions as obtained in steps (e.3) and (e.4) and concluding a true direction φ

to the target.

29. A direction finder according to claim 28, wherein said wireless communication unit, controlled attenuator, and hybrid junction are implemented by software.

30. A direction finder according to claim 28, for finding a 2D direction to the target.

31. A direction finder according to claim 28, for further finding the elevation of the target with respect to the direction finder, wherein the processing unit is further used for:

while maintaining said plane of the direction finder essentially vertical, performing steps (e.1)-(e.3), resulting in determination of one or more elevation angles θ

between the direction finder and the target.

32. A direction finder according to claim 30, further comprising a tilt sensor for measuring the tilt angle δ

of the direction finder relative to an axis vertical to the horizon, and subtracting this tilt angle from the determined elevation angle θ

to obtain a true elevation angle, thereby compensating for a case where the direction finder is not held perfectly vertical.