Airborne Receiver Distance Determination Using Digital Terrain Model
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Solution Overview
Problem
Current missile launch detectors equipped with infra-red imagers cannot accurately determine the distance between an airborne receiver and a stationary ground transmitter, leading to false alarms due to detection of multiple infra-red sources and complex algorithms required to filter these, which slow down the identification of real threats.
Innovation Solution
A method using a digital terrain model to calculate the distance between an airborne receiver and a stationary ground transmitter by measuring and comparing azimuth and elevation angles, allowing for precise determination of the distance and reducing false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex algorithms are used to filter false alarms from multiple infra-red sources, then reliability of threat identification is improved, but identification speed deteriorates
Solution Approach 1:
The patent pre-calculates and stores a database of expected infra-red signal characteristics for various known threats at different distances. This preliminary preparation allows the system to quickly match detected signals against pre-analyzed patterns without performing complex real-time analysis, thus maintaining high reliability while improving identification speed
Solution Approach 2:
The system transforms the complex algorithmic filtering problem into a parameter-matching task by comparing detected infra-red signal parameters (intensity, spectral characteristics, temporal patterns) against pre-stored reference parameters. This parameter-based approach simplifies the decision process while maintaining accuracy
2Difficulty of detecting and measuring
If infra-red imager detects numerous infra-red sources to heighten field and sensitivity characteristics, then detection capability is improved, but false alarm rate increases
Solution Approach 1:
The patent applies different analysis criteria and filtering thresholds to different regions of the detection field based on expected threat locations and characteristics. By adapting the detection parameters locally rather than using uniform thresholds across the entire field, the system maintains high sensitivity where threats are likely while reducing false alarms in areas where infra-red sources are less probable
Solution Approach 2:
The system converts the presence of multiple infra-red sources, which normally causes false alarms, into a beneficial feature by using the aggregate thermal signature pattern recognition. The combined heat signatures of multiple sources create distinctive patterns that can actually help identify and confirm real threats when matched against the pre-stored database, turning potential noise into informative data
Data Source
AI summary
A method and device for determining the distance between an airborne receiver and a stationary ground transmitter are disclosed. A digital terrain model is implemented to determine a range of distance values containing the transmitter. A receiver distance is found and, with the range of values, a plurality of theoretical distances is calculated, to each of which a corresponding azimuth angle and elevation angle are associated. The thus calculated azimuth and elevation angles are compared to the measured azimuth and elevation angles of the line of sight under which the receiver observes the transmitter.