Radar Receiver Apodization of Spurious Signals via Multi-Channel Phase Modulation
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Solution Overview
Problem
Radar systems face performance degradation due to spurious signals, known as 'spurs,' which can lead to false targeting and reduced accuracy, despite advancements in component stability and circuit design.
Innovation Solution
The approach involves modulating a received radar signal into two paths with different modulation schemes, allowing for the generation of two radar images with identical target responses but distinct spurious energy locations, enabling the identification and removal of spurious energy by combining these images and applying an energy threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional component selection and circuit construction techniques are used to minimize spur creation, then component stability is improved, but spurious signals still survive and cause false targeting
Solution Approach 1:
The radar signal processing is divided into multiple independent channels (first channel and second channel), each processing the signal differently. By segmenting the processing paths and combining results, the system can identify and eliminate spurious signals that appear in only one channel while preserving true targets that appear in both channels.
Solution Approach 2:
The patent changes processing parameters between channels by applying different modulation schemes (first modulation and second modulation) to the same input signal. This parameter variation causes spurious signals to manifest differently in each channel, enabling their identification and removal through comparison.
2Measurement precision
If multi-channel processing with different modulation schemes is applied, then spurious energy discrimination is improved, but device complexity increases
Solution Approach 1:
The multiple signal processing channels serve dual functions: they both process the radar signal for target detection and simultaneously enable spurious signal identification through their different modulation approaches. This multi-functionality improves measurement precision without requiring entirely separate systems.
Solution Approach 2:
The patent merges the outputs of multiple processing channels by combining the first radar image and second radar image. This combining operation integrates the benefits of different modulation schemes while maintaining a unified processing framework, managing complexity through consolidation rather than separate independent 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 method effectively discriminates between true target energy and spurious energy, enhancing radar system accuracy by removing spurious signals and improving target detection reliability.
Implementation Method 1
a phase modulator that modulates a phase of the second signal
Data Source
AI summary
The various technologies presented herein relate to identification and mitigation of spurious energies or signals (aka “spurs”) in radar imaging. Spurious energy in received radar data can be a consequence of non-ideal component and circuit behavior. Such behavior can result from I/Q imbalance, nonlinear component behavior, additive interference (e.g. cross-talk, etc.), etc. The manifestation of the spurious energy in a radar image (e.g., a range-Doppler map) can be influenced by appropriate pulse-to-pulse phase modulation. Comparing multiple images which have been processed using the same data but of different signal paths and modulations enables identification of undesired spurs, with subsequent cropping or apodization of the undesired spurs from a radar image. Spurs can be identified by comparison with a threshold energy. Removal of an undesired spur enables enhanced identification of true targets in a radar image.