Enhanced Passive Coherent Location Techniques to Track and Identify UAVs, UCAVs, MAVs, and Other Objects

• US 20080088508A1
• Filed: 05/15/2007
• Published: 04/17/2008
• Est. Priority Date: 03/05/1999
• Status: Active Grant

• Current Assignee: ERA as (Omnipol as)
• Original Assignee: ERA Systems Corporation (General Dynamics Corporation)
• Inventors: Smith, Alexander
• Granted Patent: US 7,782,256 B2
• Time in Patent Office: Days
• US Class Current: 342/453
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/66 Radar-tracking systems; Analogous systems
• CPC Class Codes: G01S 13/726 Multiple target tracking
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

A system and technique is described which has the capability to track and identify, in real time, various aircraft and objects including Unmanned Aerial Vehicles (UAVs), Unmanned Combat Aerial Vehicles (UCAVs), and Micro Aerial Vehicles (MAVs). The system uses a combination of techniques including conventional automatic dependent surveillance broadcast (ADS-B), transponder multilateration, broadband emitter multilateration, primary and secondary radar, and passive coherent location. A series of enhancement to conventional passive coherent location are described.

Claims

1. A system for tracking an object, comprising:

means for receiving a reference transmission from a controlled or uncontrolled transmitter, and a scattered transmission that originated from a controlled or uncontrolled transmitter and scattered by the object;

means for comparing the received transmissions to determine a frequency-difference-of-arrival thereby establishing a track or tracks for the object or objects; and

means for updating each track on a predetermined periodic basis, and forwarding each track to the system'"'"'s processing unit for filtering and display.

2. The system of claim 1, wherein the transmissions include one or more of FM radio, Digital Video Broadcast Terrestrial (DVB-T), Digital Audio Broadcast (DAB), and Global System for Mobile Communications (GSM).

3. The system of claim 1, wherein the system combines one or more of portable and fixed multilateration, ADS-B, Passive Emitter Tracking (PET), and Passive Coherent Location (PCL) receiver systems sharing the same antenna mast, power, communications, and infrastructure for ease of deployment.

4. The system of claim 1 wherein the system combines a mobile or fixed based system combines Passive Emitter Tracking (PET) and Passive Coherent Location (PCL) to provide real-time tracking and characterization or identification of cooperative and non cooperative targets including land, sea, and airborne targets.

5. The system of claim 4, wherein the PET includes direction finding using phase of received target emissions and Time Difference of Arrival (TDOA) processing of the received target emissions.

6. The system of claim 4, where the PCL includes TDOA processing of signals reflected by cooperative and non-cooperative targets.

7. The system of claim 4, wherein the characterization or identification includes electronic intelligence of target emissions and target classification based on modulation of the reflected signals.

8. A system for narrowband pre-detection signal processing for passive coherent location applications comprising:

a database of a priori illuminator signals;

means for receiving an input signal including a target signal and a reference signal, the reference signal being received on a direct path from a controlled or uncontrolled transmitter and the target signal comprising the reference signal reflected from a target; and

means for correlation signal processing of the target signal and the reference signal using the database of a priori illuminator signals to discriminate between reference signals and target signals.

9. The system of claim 8, wherein the system comprises one of a mobile or fixed based system combining combines Passive Emitter Tracking (PET) and Passive Coherent Location (PCL) to share system infrastructure.

10. The system of claim 9, wherein the PET and the PCL are co-mounted on an antenna mast and use the same communications channels from the sensors to the central server.

11. The system of claim 9, where the PET may be mounted on a plurality of masts having all or a subset equipped with PCL sensors, and where each PCL sensor may track based on the same or different frequency bands, including terrestrial and satellite based radio, television, and other CW sources.

12. The system of claim 9, further comprising means for tracking an tracking and identifying aircraft from one or more of ADS-B, multilateration, broadband passive emitter tracking, SSR, primary radar, and PCL.

13. The system of claim 12, further comprising means for prioritizing data sources in order to provide comprehensive surveillance and a back up or validation to the preferred sources used for air traffic control.

14. The system of claim 9, further including means for using electronic intelligence from broadband passive emitter tracking coupled with PCL extracted target characteristics to provide high confidence in target identification and classification.

15. The system of claim 9, further including a database of one or more of PET and PCL features for vehicles, vessels, and aircraft, including one or more of UAVs, UCAVs, and MAVs.

16. A method for mitigating co-channel interference in passive coherent location applications comprising the steps of:

storing, in a database, a priori knowledge of proximate illuminator signals, wherein the illuminator signals comprise one or more of FM radio, Digital Video Broadcast Terrestrial (DVB-T), Digital Audio Broadcast (DAB), and Global System for Mobile Communications (GSM);

generation of the illuminators from the database, and

canceling the illuminator signals from the co-channel signals to remove co-channel interference.

17. A method for continuously detecting and extracting target information from a series of samples within a passive coherent location system, comprising the steps of:

forming an ambiguity surface having ambiguity surface data for the series of samples; and

extracting target information from the series of samples from the ambiguity surface data, and

comparing extracted target information in a processing system with a database of predetermined target type characteristics.

18. A method for associating detections to a line track, where the line track correlates to a signal transmitted from at least one of a controlled and uncontrolled source, reflected from a target, and detected by a passive coherent location system, comprising the steps of:

determining a line track vector from a series of measurements using a set of filters, wherein the measurements are at least partially derived by comparing the signal to a reference transmission from the controlled or uncontrolled source, and

generating a track comparable to conventional air traffic control radar systems, including two air traffic control tracker states of track and coast.