Harmonic Shuttered Seeker Using One FPA for PRF Target Detection
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Solution Overview
Problem
Multi-mode/multi-homing seeker systems for projectiles are complex and costly, with increased parts leading to reduced reliability and longer target acquisition times, while passive image-based seekers face challenges in distinguishing targets from background clutter.
Innovation Solution
The harmonic shuttering methodology uses a single FPA to achieve both active laser-based and passive image-based modes by dividing the pulse interval into subintervals, ensuring accurate detection and decoding of laser pulses within two pulse intervals, thereby reducing complexity and cost while improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors and processing systems are integrated to achieve multi-mode/multi-homing capability, then the precision and accuracy of target detection are improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies universality by enabling a single FPA sensor to perform multiple functions: detecting laser pulses in semi-active mode and capturing ambient light for passive imaging mode. The FPA is configured to detect specific wavelengths for laser detection while also capturing visible spectrum for passive imaging, eliminating the need for separate sensor systems for each mode.
Solution Approach 2:
The patent merges the functionality of separate laser detection systems and passive imaging systems into a single integrated FPA-based system. The FPA simultaneously handles both semi-active laser tracking and passive image-based target acquisition, reducing the number of components and simplifying the overall seeker architecture.
2Measurement precision
If multiple sensors and processing systems are integrated to achieve multi-mode/multi-homing capability, then the precision and accuracy of target detection are improved, but the reliability decreases
Solution Approach 1:
By making the FPA universal for both semi-active and passive modes, the patent reduces the total number of components in the system. Fewer components mean fewer potential failure points, thereby improving reliability while maintaining multi-mode capability through the versatile FPA sensor.
3Measurement precision
If complex processing algorithms are used to distinguish target from background clutter, then the accuracy of target identification is improved, but the target acquisition time increases
Solution Approach 1:
The patent employs periodic action through harmonic shuttering, where the FPA is rapidly alternated between detecting laser pulses and capturing ambient light at specific frequencies. This periodic switching allows the system to efficiently separate laser pulse detection from passive imaging, enabling quick identification of laser-designated targets while maintaining the ability to perform passive target acquisition when needed.
Solution Approach 2:
The patent segments the detection process into distinct time intervals: laser pulse detection periods and passive imaging periods. By dividing the operational cycle into these segments, the system can quickly identify laser pulses during designated time windows while minimizing interference from ambient light, thereby reducing target acquisition time.
4Measurement precision
If the frame rate is increased to capture more laser pulses, then the detection accuracy is improved, but the energy consumption and system complexity increase
Solution Approach 1:
The patent uses periodic action by operating the FPA at a frame rate that is an odd multiple of the laser pulse repetition frequency. This harmonic relationship ensures that the FPA captures laser pulses at predictable intervals while maintaining lower overall frame rates compared to continuous high-speed capture, thereby reducing energy consumption while preserving detection accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the speed, accuracy, and cost-effectiveness of seeker systems by quickly identifying the correct pulse repetition frequency, reducing the likelihood of missed pulses, and distinguishing designated laser energy from ambient confusion, thus improving the overall performance of multi-mode/multi-homing seeker systems.
Implementation Method 1
a seeker system of the ordinance detects the laser energy
Implementation Method 2
dividing the pulse interval into subintervals, ensuring accurate detection and decoding of laser pulses within two pulse intervals
Data Source
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AI summary
A dual-mode, semi-active, laser-based and passive image-based seeker for projectiles, missiles, and other ordnance that persecute targets by detecting and tracking energy scattered from targets. The disclosed embodiments use a single digital imager having a single focal plane array sensor to sense data in both the image-based and laser-based modes of operation. A shuttering technique allows the relatively low frame-rate of the digital imager to detect, decode and localize in the imager's field-of-view a known pulse repetition frequency (PRF) from a known designator in the presence of ambient light and other confusing target designators, each having a different PRF.