Indirect Radar Detection of Low RCS Objects
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Solution Overview
Problem
Existing radar systems face challenges in detecting objects with low radar cross-section (RCS) due to their low reflectivity and absorption of high-frequency signals, making it difficult to distinguish them from clutter in environments with significant RCS objects.
Innovation Solution
The method involves determining a steady state response profile of an environment without low RCS objects and comparing it to a test response profile to identify the presence of low RCS objects by detecting partial or complete absence of reflected signals, using radar frequencies of 2 GHz or higher, and estimating their position and velocity based on these differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radar detection is used at high frequencies (≥2 GHz) to detect low RCS objects, then the detection capability for small objects is improved, but the ability to distinguish them from clutter is worsened
Solution Approach 1:
The system performs preliminary action by capturing a steady state response profile of the environment before attempting to detect low RCS objects. This baseline profile, stored in memory, represents the environment without low RCS objects present. When detection is needed, the system compares the current test response profile against this pre-captured steady state profile, enabling effective clutter discrimination even at high frequencies where clutter is significant.
2Reliability
If radar signals are transmitted to detect low RCS objects, then object detection is enabled, but the reflected signals are absorbed and lost
Solution Approach 1:
The system applies inversion by detecting the absence rather than the presence of reflected signals. Instead of trying to detect the weak reflected signals from low RCS objects directly (which are absorbed and lost), the system detects what is missing from the environment's response profile. When a low RCS object is present, it blocks or absorbs signals that would otherwise reflect from background objects, creating detectable absences in the response profile compared to the steady state baseline.
3Quantity of substance
If the environment contains significant RCS objects (clutter), then the environment provides detectable reflected signals, but low RCS objects become indistinguishable from the clutter
Solution Approach 1:
The system extracts the clutter component from the total environmental response by comparing the test response profile against the steady state response profile. The steady state profile contains only clutter reflections (without low RCS objects), while the test profile contains both clutter and any low RCS objects. By taking the difference or comparing the two profiles, the system extracts and identifies only the portions attributable to low RCS objects, effectively separating target from clutter.
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 allows for effective detection and estimation of low RCS objects, such as humans or animals, within environments cluttered with high RCS objects, improving the accuracy of radar systems by differentiating between target and background objects.
Implementation Method 1
Known radar systems are designed to detect and measure parameters of a 'target' by transmitting known Radio Frequency (RF) waveforms, and then receiving and processing the signals reflected back from the target
Implementation Method 2
The strength of a returned signal reflected off an object depends on the radar cross section (RCS) of that object
Implementation Method 3
estimate of range to the scattering centre via its transmission delay (Joseph B. Keller. Geometrical theory of diffraction. Journal of the Optical Society of America, 52(2):116-130, February 1962)
Data Source
AI summary
A method, apparatus, and system for detecting presence of an object of low radar cross section RCS (250) in an environment (200) are provided. Radar detection at one or more radar frequencies greater than 2 GHz is used to determine a steady state response profile (300) of the environment (200). The steady state response profile (300) comprises at least one indication of one or more reflected signals (202) from an object of high RCS in the environment (200). Radar detection at the one or more radar frequencies is then used to determine a test response profile (600) of the environment (200). The test response profile (600) is compared with the steady state response profile (300) to determine a presence of a, object of low RCS (250) in the environment by identifying at least partial absence of at least one of the reflected signals (202) in the test response profile (600).