Tracking apparatus and method for airborne targets

• US 10,302,755 B2
• Filed: 05/20/2014
• Issued: 05/28/2019
• Est. Priority Date: 05/20/2014
• Status: Active Grant

• Current Assignee: SpotterRF LLC
• Original Assignee: SpotterRF LLC
• Inventors: Harris, Logan Carl
• Primary Examiner(s): McGue, Frank J
• Application Number:
  US14/282,829
• Publication Number:
  US 20170102460A1
• Time in Patent Office: 1,834 Days
• Field of Search: 342 21
• CPC Class Codes: G01S 13/4454 phase comparisons monopulse, i.e. comparing the echo signals received by an interferometric antenna arrangement
• CPC Class Codes: G01S 13/72 for two-dimensional tracking, e.g. combination of angle and range tracking, track-while-scan radar
• CPC Class Codes: H01Q 1/125 Means for positioning
• CPC Class Codes: H01Q 3/08 for varying two co-ordinates of the orientation

Abstract

A method for determining location information for an airborne target includes synthesizing a cyclic transmit signal, transmitting an electromagnetic beam corresponding to the cyclic transmit signal, providing a plurality of vertically offset return signals corresponding to at least two receive antennas that are vertically offset, down-converting the plurality of vertically offset return signals with the cyclic transmit signal to provide a corresponding plurality of baseband signals, determining magnitude and phase information for each vertically offset return signal as a function of range from the corresponding baseband signal, and determining elevation information for an airborne target from the magnitude and phase information. Azimuthal information for the airborne target may be determined by tracking amplitude variations in the return signal in response to azimuthal rotation of the receive antennas. A corresponding apparatus, system, and computer readable medium are also disclosed herein.

Claims

1. An apparatus for determining location information for an airborne target, the apparatus comprising:

a signal generation module configured to synthesize a cyclic transmit signal having a fixed frequency slope over a substantial portion of each cycle;

an antenna array comprising at least one transmit antenna configured to emit an electromagnetic beam corresponding to the cyclic transmit signal wherein the electromagnetic beam spans more than 30 degrees in elevation and less than 12 degrees in azimuth;

the antenna array further comprising at least two receive antennas that are vertically offset and configured to provide a corresponding plurality of vertically offset return signals;

a down-conversion module configured to down-convert the plurality of vertically offset return signals with the cyclic transmit signal to provide a corresponding plurality of baseband signals;

a magnitude and phase extraction module configured to receive the plurality of baseband signals and provide magnitude and phase information for each return baseband signal as a function of range;

a filtering module configured to filter out transient peaks in the magnitude information;

a target tracking module configured to receive the magnitude and phase information and determine elevation information for an airborne target corresponding to a peak in the magnitude information; and

wherein the target tracking module is configured to determine azimuthal information for the airborne target in response to physical azimuthal rotation of the antenna array.

2. The apparatus of claim 1, wherein azimuthal information is determined by tracking amplitude variations in the return signal, or a signal corresponding thereto, in response to azimuthal rotation of the antenna array.

3. The apparatus of claim 1, wherein the target tracking module is configured to orientate the antenna array according to the elevation information and the azimuthal information.

4. The apparatus of claim 1, wherein the electromagnetic beam is emitted without up-conversion of the cyclic transmit signal.

5. The apparatus of claim 1, further comprising a behavior filter configured to observe movements of a potential target and thereby determine if the potential target is not an aircraft.

6. The apparatus of claim 1, further comprising a target classification module configured to use microdoppler information to classify the airborne target.

7. A computer-implemented method for determining location information for an airborne target, the method comprising:

synthesizing a cyclic transmit signal having a fixed frequency slope over a substantial portion of each cycle;

transmitting an electromagnetic beam corresponding to the cyclic transmit signal wherein the electromagnetic beam spans more than 30 degrees in elevation and less than 12 degrees in azimuth;

providing a plurality of vertically offset return signals corresponding to at least two receive antennas that are vertically offset;

down-converting the plurality of vertically offset return signals with the cyclic transmit signal to provide a corresponding plurality of baseband signals;

determining magnitude and phase information for each vertically offset return signal as a function of range from the corresponding baseband signal;

filtering out transient peaks in the magnitude information;

determining elevation information for an airborne target that corresponds to a peak in the magnitude information from the magnitude and phase information; and

determining azimuthal information for the airborne target in response to physical azimuthal rotation of the antenna array.

8. The method of claim 7, wherein azimuthal information is determined by tracking amplitude variations in the return signal, or a signal corresponding thereto, in response to azimuthal rotation of the receive antennas.

9. The method of claim 7, further comprising orientating the antenna array according to the elevation information and the azimuthal information.

10. The method of claim 7, further comprising observing movements of a potential target to determine if the potential target is not an aircraft.

11. The method of claim 7, further comprising using microdoppler information to classify the airborne target.

12. A non-transitory computer readable medium having computer executable instructions stored thereon that when executed by a digital processing apparatus cause the digital processing apparatus to conduct a method for determining location information for an airborne target, the method comprising:

synthesizing a cyclic transmit signal having a fixed frequency slope over a substantial portion of each cycle;

transmitting an electromagnetic beam corresponding to the cyclic transmit signal wherein the electromagnetic beam spans more than 30 degrees in elevation and less than 12 degrees in azimuth;

providing a plurality of vertically offset return signals corresponding to at least two receive antennas that are vertically offset;

down-converting the plurality of vertically offset return signals with the cyclic transmit signal to provide a corresponding plurality of baseband signals;

determining magnitude and phase information for each vertically offset return signal as a function of range from the corresponding baseband signal;

filtering out transient peaks in the magnitude information;

determining elevation information for an airborne target that corresponds to a peak in the magnitude information from the magnitude and phase information; and

determining azimuthal information for the airborne target in response to physical azimuthal rotation of the receive antennas.

13. The computer readable medium of claim 12, wherein azimuthal information is determined by tracking amplitude variations in the return signal, or the signal corresponding thereto, in response to azimuthal rotation of the receive antennas.

14. The computer readable medium of claim 12, wherein the method further comprises orientating the antenna array according to the elevation information and the azimuthal information.

15. The computer readable medium of claim 12, wherein the method further comprises observing movements of a potential target to determine if the potential target is not an aircraft.

16. The computer readable medium of claim 12, wherein the method further comprises using microdoppler information to classify the airborne target.

17. The computer readable medium of claim 12, wherein the electromagnetic beam is transmitted without up-conversion of the cyclic transmit signal.