Multitone Radar Using Nonlinear Intermodulation for Target Detection
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Solution Overview
Problem
Traditional radar systems face challenges in distinguishing between electronic devices and clutter, particularly in detecting unshielded RF electronics, due to their reliance on linear responses, which often result in high false alarm rates and require higher power to achieve a comparable signal-to-noise ratio.
Innovation Solution
The development of a nonlinear radar system that exploits both magnitude and phase information in intermodulation products to create an instantaneous stepped-frequency waveform, allowing for the simultaneous measurement of all frequency samples required by a stepped-frequency radar system, thereby enhancing target detection and classification capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional linear radar is used to detect electronic devices, then the detection capability is limited by high clutter interference, but increasing the transmitted power to improve signal-to-noise ratio results in higher energy consumption and still produces high false alarm rates
Solution Approach 1:
The patent converts the harmful effect of clutter reflection into a useful signal by exploiting the nonlinear response of electronic devices. When the radar transmits a multi-tone waveform, electronic devices generate intermodulation products at frequencies different from the transmitted tones, while clutter only produces linear reflections at the transmitted frequencies. This allows the system to detect electronic devices by receiving frequencies that are not part of the transmitted probe, effectively converting clutter interference into a discrimination mechanism.
Solution Approach 2:
The patent changes the frequency parameter by transmitting a multi-tone waveform instead of a single frequency, and by receiving intermodulation products at different frequencies. This parameter change enables the system to distinguish electronic devices from clutter based on their different frequency responses, improving detection accuracy without increasing transmitted power.
2Reliability
If traditional linear radar is used to distinguish electronic devices from clutter, then the system requires high transmitted power to achieve acceptable signal-to-noise ratio, but this still results in high false alarm rates due to inability to separate targets from clutter
Solution Approach 1:
The patent converts the harmful effect of clutter reflection into a useful signal by exploiting the nonlinear response of electronic devices. When the radar transmits a multi-tone waveform, electronic devices generate intermodulation products at frequencies different from the transmitted tones, while clutter only produces linear reflections at the transmitted frequencies. This allows the system to detect electronic devices by receiving frequencies that are not part of the transmitted probe, effectively converting clutter interference into a discrimination mechanism.
Solution Approach 2:
The patent changes the frequency parameter by transmitting a multi-tone waveform instead of a single frequency, and by receiving intermodulation products at different frequencies. This parameter change enables the system to distinguish electronic devices from clutter based on their different frequency responses, improving detection accuracy without increasing transmitted power.
3Loss of information
If stepped-frequency radar is used to obtain complete target signature, then all frequency samples can be measured simultaneously, but the system complexity increases due to the need for multiple frequency components and processing
Solution Approach 1:
The patent employs a single nonlinear target detector that automatically generates and processes all necessary frequency components. The multi-tone waveform generator creates the required frequency spectrum, and the nonlinear target detector inherently produces intermodulation products at all relevant frequencies through its nonlinear response to electronic devices. This self-service approach obtains complete target signatures without requiring multiple separate detectors or complex external processing systems.
Solution Approach 2:
The patent changes the frequency parameter by transmitting a multi-tone waveform instead of a single frequency, and by receiving intermodulation products at different frequencies. This parameter change enables the system to distinguish electronic devices from clutter based on their different frequency responses, improving detection accuracy without increasing transmitted power.
4Device complexity
If single-frequency radar is used to detect nonlinear targets, then the system is simpler to implement, but it cannot obtain complete target signature or determine range accurately
Solution Approach 1:
The patent changes the frequency parameter by transmitting a multi-tone waveform instead of a single frequency, and by receiving intermodulation products at different frequencies. This parameter change enables the system to distinguish electronic devices from clutter based on their different frequency responses, improving detection accuracy without increasing transmitted power.
Solution Approach 2:
The patent employs a single nonlinear target detector that automatically generates and processes all necessary frequency components. The multi-tone waveform generator creates the required frequency spectrum, and the nonlinear target detector inherently produces intermodulation products at all relevant frequencies through its nonlinear response to electronic devices. This self-service approach obtains complete target signatures without requiring multiple separate detectors or complex external processing systems.
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 enables more accurate and efficient detection of RF electronic devices by reducing false alarms and requiring lower power, while maintaining unambiguous range and providing a complete target signature from a single transmitted waveform.
Implementation Method 1
nonlinear radar exploits the electronic response from a target whose reflected frequencies are different from those transmitted
Implementation Method 2
reception of frequencies that are not part of the transmitted probe distinguishes the received signal from a linear return that can be produced by clutter and indicates the presence of an electronic circuit
Data Source
AI summary
Method for determining distance to target using a multitone nonlinear radar system comprising providing a transmitter that transmits a signal comprising at least two predetermined frequency components; receiving transmitted signal upon reflection from target; determining the phase relationships of the frequency components when signal strikes target; determining distance the signal has travelled to target based upon the phase relationship of the frequency signal components at the time of reflection from target; computing the distance to target. A system comprising a transmitter subsystem that transmits radar signal comprising at least two frequency components; a receiver subsystem configured to receive a return signal comprising intermodulation and harmonic products; at least one processor configured to extract frequency samples from the return signal within a frequency range, apply a window function to the extracted frequency samples and perform an inverse fast Fourier transform on the resulting function to create a range profile.