Communications: electrical – Aircraft alarm or indicating systems
Reexamination Certificate
2002-08-12
2004-11-23
Tweel, John (Department: 2636)
Communications: electrical
Aircraft alarm or indicating systems
C701S223000
Reexamination Certificate
active
06822583
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to aircraft such as tactical fighters that can employ passive technology for early target detection and target tracking, and specifically to an improved method that enhances the implementation of tactical fighter configuration data and sensor assets for passively tracking maneuvering or non-maneuvering airborne RF emitters, which represent targets or threats, to enhance the tactical fighter's ability to intercept and destroy incoming targets.
2. Description of Related Art
Modern warfare requires the airborne defense of military and civilian targets, typically by tactical fighters, whose job it is to seek out and destroy incoming enemy aircraft seeking to destroy friendly military and civilian complexes, whether on ground or at sea. At the current speeds and aircraft stealth configurations of potential target aircraft, there exists a critical need for rapid but accurate passive target range, speed, and heading estimates (with quality factors) in order to prioritize incoming aircraft threats for purposes of avoidance and targeting. The complex problem requires a total integration of all of the tactical fighter's onboard and remote (offboard) assets. The entire fighter weapon system, which includes remote support help with satellite and ground communications, and radar, must be completely integrated and used with all the onboard aircraft avionics equipment, including ownship and linked wingmen weapons systems to maximize the ability of the tactical fighter to totally avoid, or to destroy enemy targets.
A very important aspect of current warfare for airborne weapon systems is to employ passive avionics systems and multispectral LO (low observable) technology to avoid detection by the oncoming targets. Present fighter aircraft do not possess a passive ranging system that leverages the electronic warfare subsystem as the primary ingredient—with exploitation of all available onboard and offboard data. The prior art shows in U.S. Pat. No. 5,408,541 issued Apr. 18, 1995, a method and system for recognizing targets at long ranges. One of the drawbacks of the system described in this patent is the fact that it is not completely passive, and it does not take advantage of all of the weapon system assets available. It involves a gated television sensor coupled with an active laser—neither of which are aboard the fighter configuration for which the invention approach discussed herein has available. Namely, it does not exploit the onboard EW (electronic warfare) system as its prime source of passive measurements.
U.S. Pat. No. 6,043,867 issued Mar. 28, 2002, shows a tracking system that includes a means for early target detection that uses the passive infrared tracking capability of infrared radiation emitted from a flying target and for generating a succession of line-of-sight (LOS) or LOS rate signals that are stored in a database. The electromagnetic finder in the system is configured to operate at first detection threshold for receiving relatively low magnitude reflections. Estimations are made of LOS and soft-stage data, facilitating early steering of the interceptor for dually homing onto the target. Again, there is no bootstrapping of the entire ownship system capabilities to solve the overall problem. It also involves an EM range finder that can be sensed by the target—using optical augmentation equipment and hence “active”—and not totally passive. The equipment are not aboard the fighter aircraft for which the invention described herein is addressing. Particularly, the invention described in U.S. Pat. No. 6,043,867 issued Mar. 28, 2002 is for an interceptor missile that utilizes passive and active tracking mechanisms—and whose flight dynamics tend toward proportional navigation (maintaining a constant line-of-sight).
The successful operation and maneuvering of a tactical fighter in an actual battle scenario places a tremendous amount of work on the pilot to accomplish a successful operation, avoiding, and/or intercepting and destroying an enemy bomber or fighter aircraft. In addition to the safe operational management of the aircraft itself, there is the requirement of a continuous and instantaneous management of the weapon systems, especially the early warning detection of threats/targets to allow ownship (and possibly cooperating action of a wingmen) to achieve target interception in the most efficient and potentially successful manner. The air-air battlespace of today, and the future, has become one that necessitates passive operation and the use of LO (low observability) management.
Thus, two aircraft, ownship and wingmen, have configuration data and sensor assets which can be used for passively detecting, initializing potential target tracks and provide passive target range, speed and heading estimates with confidence to the initialized tracks and to provide the mechanism to maintain or drop tracks, for both non-maneuvering and maneuvering incoming airborne RF emitters, which could be either threats (defensive posture) or real targets (offensive posture).
The present invention provides for a solution of this problem, which includes providing a method and system for a flyable airborne RF emitter (friendly/unfriendly) location solution in the cockpit by bootstrapping batch maximum likelihood (ML), probabilistic data association filter (PDAF), and recursive interacting multiple model (IMM) methodologies that use 1) the electronic warfare aperture assets such as embedded antennas within the aircraft structure, 2) the electronic warfare interferometer measurements, such as the cosine of cone angle, 3) pulse descriptor word (PDW) data, 4) a priori mission data, 5) real-time mission constraints, and 6) available real time track information from other onboard avionics and off-board information sources. By utilizing the present invention, the entire weapon system on board ownship and wingmen abilities are enhanced to attain the most rapid and accurate passive target range, speed, and heading estimates and their associated quality values.
The present invention involves the enhancement and modification in order to bootstrap the approach presented in IEEE paper entitled “Bearings—Only Tracking of Maneuvering Targets Using a Batch Recursive Estimator,” published in IEEE
Transactions On Aerospace And Electronic Systems
, Volume 37, No. 3, Jul. 2001. The paper approach describes a batch recursive estimator for tracking maneuvering targets from bearings-only measurements in clutter, such as low signal-to-noise ratio targets. The IEEE paper examines the sonar application. This invention requires extensive reshaping for airborne application. The approach was used to combine batch maximum likelihood probabilistic data association (ML-PDA) estimator with the recursive interacting multiple model (IMM) estimator with probabilistic data association (PDA) to result in better tracking initialization, as well as track maintenance results in the presence of clutter. The methodology describes also how batch a recursive estimator can be used for adaptive decisions for ownship maneuvers based on target state estimation to enhance target observability.
The present invention provides a method and system that can bootstrap the approach presented in this article to greatly enhance passive airborne RF target range, speed, and heading convergence for an airborne RF emitter. The present invention also deals with the inner workings of the interacting multiple model. A novelty of the invention is the “pilot maneuver cue processing” that provides the pilot the optimal maneuver to perform passive ranging subject to the critical constraints of (a) time-allotted for the ranging solution, (b) current ownship speed and heading with respect to the threat/target, (c) current ownship multispectral LO (low observability) contour map ‘presented’ to the target/threat, (d) real-time, tightly-coupled IR/EO defensive aid suite missile (SAM—surface-to-air; AAM—air-to-air) launch status, and (e) IFDL (intra-inter flight data link
Carroll Melvin
Toohey Edward F.
Yannone Ronald M.
BAE Systems Information and Electronic Systems Integration Inc.
Haley Barry L.
Tweel John
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