Positioning system with intentional multi-path signal

• US 7,315,275 B2
• Filed: 04/11/2005
• Issued: 01/01/2008
• Est. Priority Date: 07/03/2003
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Navcom Technology, Inc. (Deere & Company)
• Inventors: Stephens, Scott Adam
• Primary Examiner(s): ALSOMIRI, ISAM A
• Application Number:
  US11/103,950
• Publication Number:
  US 20050270227A1
• Time in Patent Office: 995 Days
• Field of Search: 342 5- 10, 342/8, 342/126, 342/146, 342/450, 342/457, 342361-365, 333/21.R, 343/756
• US Class Current: 342/146
• CPC Class Codes: G01S 13/4418 with means for eliminating radar-dependent errors in angle measurements, e.g. multipath effects
• CPC Class Codes: G01S 13/449 Combined with MTI or Doppler processing circuits
• CPC Class Codes: G01S 13/75 using transponders powered from received waves, e.g. using passive transponders , or using passive reflectors
• CPC Class Codes: G01S 13/876 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S13/874 takes precedence
• CPC Class Codes: G01S 2013/466 by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
• CPC Class Codes: G01S 2013/468 by Triangulation, i.e. two antennas or two sensors determine separately the bearing, direction or angle to a target, whereby with the knowledge of the baseline length, the position data of the target is determined
• CPC Class Codes: G01S 3/72 Diversity systems specially adapted for direction-finding
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G01S 7/026 involving the transmission of elliptically or circularly polarised waves
• CPC Class Codes: G01S 7/4078 involving an integrated reference reflector or reference transponder

Abstract

A positioning system includes a device, having an antenna and a reflector with a known position proximate to the antenna, that transmits at least an electromagnetic pulse having a carrier signal frequency. The device receives a return signal over a period of time, wherein the return signal includes a return pulse from an object within a radar detection area of the device and at least one multi-path pulse. The device processes the return signal so as to isolate the return pulse and the at least one multi-path pulse from the return signal. The device determines a range from the device to the object and the position of the device relative to the object. The range is determined in accordance with a time of arrival of the return pulse and the position is determined in accordance with a time of arrival of the at least one multi-path pulse.

Claims

1. A method of determining the position of a device, comprising:

transmitting at least an electromagnetic pulse having a carrier signal frequency from the device;

receiving a return signal over a period of time, wherein the return signal includes a return pulse from an object within a radar detection area of the device and at least one multi-path pulse associated with a reflector at a known position relative to and proximate to the device;

wherein the at least one multi-path pulse comprises at least one pulse that has been generated by both the object and the reflector; and

processing the return signal so as to isolate the return pulse and the at least one multi-path pulse from the return signal and to determine a range from the device to the object and the position of the device relative to the object, including determining the range in accordance with a time of arrival of the return pulse and determining the position in accordance with a time of arrival of the at least one multi-path pulse.

2. The method of claim 1, wherein the pulse during transmitting is polarized and the receiving preferentially receives the return signal having the polarization.

3. The method of claim 2, wherein the polarization is selected from the group consisting of linear polarization, elliptical polarization, right-hand elliptical polarization, left-hand elliptical polarization, right-hand circular polarization and left-hand circular polarization.

4. The method of claim 1, further comprising using a same polarized antenna for both the transmitting and receiving.

5. The method of claim 1, wherein the object is a passive reflector.

6. The method of claim 1, wherein the object is an active landmark.

7. The method of claim 1, wherein the reflector is an active reflector.

8. The method of claim 1, wherein the reflector is a passive reflector.

9. The method of claim 1, further comprising:

moving the device at a velocity in a particular direction while performing the receiving;

detecting a Doppler shift in the return pulse in the return signal; and

determining an angle between the particular direction and a straight line between the device and the object in accordance with the detected Doppler shift.

10. A positioning system, comprising a device, including an antenna and a reflector with a known position relative to and proximate to the antenna, configured to transmit at least an electromagnetic pulse having a carrier frequency, to receive a return signal over a period of time in a receiver, the return signal including a return pulse from an object within a radar detection area of the device and at least one multi-path pulse associated with the reflector, wherein the at least one multi-path pulse comprises at least one pulse that has been generated by both the object and the reflector, to process the return signal so as to isolate the return pulse and the at least one multi-path pulse from the return signal, and to determine a range from the device to the object and a position of the device relative to the object,

wherein the range is determined in accordance with a time of arrival of the return pulse and the position is determined in accordance with a time of arrival of the at least one multi-path pulse.

11. The system of claim 10, wherein the transmitted pulse is polarized and the device is configured to preferentially receive the return signal having the polarization.

12. The system of claim 11, wherein the polarization is selected from the group consisting of linear polarization, elliptical polarization, right-hand elliptical polarization, left-hand elliptical polarization, right-hand circular polarization and left-hand circular polarization.

13. The system of claim 10, wherein the antenna is configured to both preferentially transmit the pulse having the polarization and to preferentially receive the return signal having the polarization.

14. The system of claim 10, wherein the antenna is selected from the group consisting of linearly polarized and circularly polarized.

15. The system of claim 10, wherein the antenna is selected from the group consisting of a bi-cone, a bi-cone with a ground plane, a helix, horizontal omni-directional, omni-directional, hemi-directional and isotropic.

16. The system of claim 10, the device further including:

a processor;

a memory; and

at least one program module, stored in the memory and executed by the processor, the at least one program module containing instructions for;

processing the return signal so as to isolate the return pulse and the at least one multi-path pulse from the return signal; and

determining the range from the device to the object and the position of the device relative to the object;

wherein the range is determined in accordance with the time of arrival of the return pulse and the position is determined in accordance with the time of arrival of the at least one multi-path pulse.

17. The system of claim 10, the device further including:

a vehicle locomotion mechanism for moving the device in a particular direction, at a velocity;

a processor;

a memory; and

at least one program module, stored in the memory and executed by the processor, the at least one program module containing instructions for;

detecting a Doppler shift in the return pulse in the return signal; and

determining an angle between the particular direction and a straight line between the device and the object in accordance with the detected Doppler shift.

18. The system of claim 10, the object further including a mechanism for moving the object in a particular direction, at a velocity;

and

the device includes;

a processor;

a memory; and

at least one program module, stored in the memory and executed by the processor, the at least one program module containing instructions for;

detecting a Doppler shift in the return pulse in the return signal; and

determining an angle between the particular direction and a straight line between the device and the object in accordance with the detected Doppler shift.

19. The system of claim 10, wherein the object is a passive reflector.

20. The system of claim 10, wherein the object is an active landmark.

21. The system of claim 10, wherein the reflector is an active reflector.

22. The system of claim 10, wherein the reflector is a passive reflector.

23. A positioning system, including device means comprising transmit means for transmitting at least an electromagnetic pulse having a carrier frequency, reflect means at a known position relative to and proximate to the transmit means for generating at least one multi-path electromagnetic pulse, and receive means for receiving a return signal over a period of time, the return signal including a return pulse from an object within a radar detection area of the device means and at least one multi-path pulse produced by the device means, wherein the at least one multi-path pulse comprises at least one pulse that has been generated by both the object and the reflect means, signal processing means for processing the return signal so as to isolate the return pulse and the at least one multi-path pulse from the return signal, and range determination means to determine a range from the device means to the object and a position of the device means relative to the object,

wherein the range is determined in accordance with a time of arrival of the return pulse and the position is determined in accordance with a time of arrival of the at least one multi-path pulse.