Passive Target Ranging via Azimuth Maneuvers
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Solution Overview
Problem
Conventional techniques for passively ranging a target aircraft from a tactical aircraft are unable to provide a sufficiently accurate estimate of the range within a short enough time window due to noise and atmosphere-induced fading, especially when relying on signal amplitudes, and are unsuitable for situations where both aircraft are traveling at constant velocities.
Innovation Solution
A computing apparatus onboard the tactical aircraft uses a range finder configured with Kalman filters to determine the azimuth range independently of signal amplitudes by assuming targets are traveling along straight-line headings, determining a coarse range, and prompting the aircraft to maneuver for accurate tracking, employing techniques like hairpin turns and sinusoidal flight paths to vary azimuth angles and induce additional derivatives in motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal amplitude is used for ranging, then ranging capability is provided, but measurement precision deteriorates due to noise and atmosphere-induced fading
Solution Approach 1:
The patent extracts the ranging function from dependence on signal amplitude by using azimuth angle measurements alone. The system separates the ranging calculation from amplitude-based methods, utilizing only directional information from the detector to compute range through geometric relationships and aircraft maneuver data, thereby eliminating noise and fading issues associated with amplitude measurements.
Solution Approach 2:
The patent replaces the signal amplitude measurement system with an azimuth angle-based ranging system. Instead of relying on electromagnetic signal strength, the system uses directional detection combined with aircraft motion data to determine target range, substituting a more reliable measurement approach that is not susceptible to atmospheric effects.
2Productivity
If conventional passive ranging is used, then target range can be estimated, but productivity deteriorates due to insufficient accuracy and time window
Solution Approach 1:
The patent employs preliminary action by having the aircraft perform specific maneuvers (such as hairpin turns or sinusoidal flight paths) before and during the ranging process. These pre-planned motion patterns create predictable changes in azimuth angles that accelerate the convergence of the ranging algorithm, enabling faster and more accurate range determination within tactical time windows.
Solution Approach 2:
The patent applies dynamics by utilizing the aircraft's motion through maneuvers to dynamically vary the azimuth angle measurements. The system processes time-varying azimuth data from aircraft maneuvers to rapidly converge on accurate range estimates, transforming the aircraft's motion into a useful resource for improving ranging speed and precision.
3Measurement precision
If radar signals are emitted for ranging, then accurate range measurement is achieved, but stealth capability deteriorates
Solution Approach 1:
The patent implements self-service by having the aircraft use its own motion and existing detector to perform passive ranging without external radar emissions. The system processes azimuth angle measurements from the aircraft's natural flight path and detector to determine target range, making the aircraft self-sufficient for ranging while maintaining stealth through passive operation.
Data Source
AI summary
In an embodiment, an apparatus includes a detector and a range finder. The detector is configured to determine a direction to a target in response to a signal received from the target, and the range finder is configured to determine a range to the target in response to the direction and independently of an amplitude of the signal. For example, such an apparatus (e.g., a computer-based apparatus) may be disposed on tactical fighter aircraft, and may be able to range (e.g., azimuth range or slant range) a target passively even if an accurate measure of the amplitude of the signal received from the target is unavailable.