Infrared Signal Processor Target Discrimination
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Solution Overview
Problem
Infrared detection systems face challenges in distinguishing tank targets from ground clutter in air-to-surface environments due to similar target signatures and cluttered backgrounds, requiring more sophisticated discrimination methods to achieve effective acquisition and tracking.
Innovation Solution
An infrared signal processor is employed, utilizing a plurality of detectors to scan the ground, with electrical signals processed through bandpass filters and pulsewidth detection circuitry to differentiate between tank targets and clutter based on pulse duration and intensity, employing a constant false alarm rate circuit and bias voltage to enhance discrimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If simple infrared detection is used, then the system is easy to operate, but it cannot distinguish tank targets from ground clutter in cluttered environments
Solution Approach 1:
The signal processing is divided into distinct sequential stages: bandpass filtering to isolate frequency components, pulsewidth detection to measure temporal characteristics, and threshold comparison to identify targets. This segmentation allows complex discrimination to be achieved through multiple simple, dedicated processing steps rather than a single complex system.
Solution Approach 2:
The system transitions from simple intensity detection to multi-dimensional analysis by introducing temporal dimension (pulsewidth measurement) and frequency dimension (bandpass filtering) in addition to the existing spatial and intensity dimensions. This dimensional expansion enables discrimination between targets and clutter based on multiple characteristic parameters simultaneously.
2Reliability
If sophisticated discrimination methods are used, then target detection accuracy improves, but the system complexity increases
Solution Approach 1:
The bandpass filter serves multiple functions: it isolates the frequency band of interest, rejects out-of-band noise, and prepares the signal for subsequent pulsewidth measurement. The pulsewidth detection circuit simultaneously measures temporal characteristics and provides input for threshold comparison. This multi-functionality reduces the need for separate dedicated circuits for each function.
Solution Approach 2:
The system dynamically adjusts the threshold voltage based on the processed signal characteristics and environmental conditions. By changing the threshold parameter adaptively, the system maintains high detection accuracy across varying operational conditions without requiring complex reconfiguration of the entire detection system.
3Measurement precision
If bandpass filtering is applied, then noise and clutter signals are reduced, but signal amplitude decreases
Solution Approach 1:
The bandpass filter is applied preliminarily to isolate the frequency components of interest before subsequent processing stages. This preliminary frequency selection ensures that only relevant signal components proceed through the pulsewidth detection and threshold comparison, improving signal purity early in the processing chain and preventing noise from contaminating later stages.
Solution Approach 2:
The system uses feedback from the pulsewidth detection and threshold comparison stages to adjust processing parameters. The constant false alarm rate circuit provides feedback that modifies the threshold voltage, allowing the system to compensate for amplitude losses from filtering by dynamically adjusting detection sensitivity based on actual signal conditions.
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 effectively discriminates tank targets from ground clutter, enabling accurate detection and tracking by rejecting noise and clutter signals, thereby improving the guidance system's ability to intercept targets in cluttered environments.
Implementation Method 1
infrared energy from objects on an area of the ground is directed towards a plurality of detectors disposed in a missile. The plurality of detectors scan the area of the ground and electrical signals produced by the detectors in response to the sensed infrared energy
Implementation Method 2
The electrical pulses are passed through a bandpass filter to reduce the amplitude of signals produced by both ground clutter infrared energy and noise
Data Source
AI summary
An infrared signal processor is provided wherein infrared energy from objects on an area of the ground is directed towards a plurality of detectors disposed in a missile. The plurality of detectors scan the area of the ground and electrical signals produced by the detectors in response to the sensed infrared energy are processed to detect the presence of a ground target, typically a tank. Potential targets are detected, that is, are distinguished from ground clutter, by determining whether electrical pulses produced by the detectors in response to the sensed infrared energy have a proper pulse duration which is consistent with the width of a tank target. In particular, the electrical pulses are passed through a bandpass filter to filter signals produced by both ground clutter infrared energy and noise.