Distributed Coherent Radar Layout for Phase Noise Estimation
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Solution Overview
Problem
Distributed coherent radar systems suffer from reduced detection performance due to uncorrelated phase noise from local oscillators in individual radar units, which is not attenuated during down mixing, particularly affecting targets with small cross-sections.
Innovation Solution
A distributed coherent radar system configuration with aligned and offset antennas in orthogonal directions, allowing phase noise estimation and cancellation without requiring antennas to act as both transmitter and receiver, thereby reducing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If local oscillators are used in each radar unit, then the radar system can operate independently and flexibly, but phase noise from different radar units becomes uncorrelated and adds up during down mixing, reducing detection performance
Solution Approach 1:
The system uses feedback from the received signals to estimate and compensate for phase noise. By continuously monitoring the phase noise characteristics in the received signals and adjusting the compensation parameters accordingly, the system maintains detection performance while using independent local oscillators in each radar unit.
Solution Approach 2:
The system changes the parameter approach by estimating phase noise as a separate component and applying compensation. Instead of relying on correlated phase noise to naturally attenuate noise during down mixing, the system actively estimates and corrects phase noise parameters to maintain detection performance.
2Measurement precision
If antennas are configured to act as both transmitter and receiver, then the system can estimate phase noise more directly, but the complexity and cost increase due to required circulators or power dividers
Solution Approach 1:
The system introduces an intermediary approach by using offset antennas as separate transmit and receive elements. Instead of requiring antennas to switch between transmit and receive modes (which would require circulators or power dividers), the system uses spatially separated antennas to establish the necessary signal paths for phase noise estimation, thereby avoiding additional complex circuitry.
Solution Approach 2:
The system segments the antenna functions into separate transmit and receive antennas positioned at offset locations. This segmentation allows independent optimization of transmit and receive paths while providing the spatial separation needed for phase noise estimation without requiring complex switching circuitry.
3Device complexity
If phase noise is not attenuated during down mixing, then the radar system can maintain simple signal processing, but detection performance deteriorates particularly for targets with small cross-section
Solution Approach 1:
The system applies preliminary action by estimating phase noise characteristics before the final detection processing stage. By preparing and compensating for phase noise effects in advance, the system simplifies subsequent signal processing while maintaining detection performance for small cross-section targets.
Data Source
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AI summary
Disclosed is a DCR system comprising: first and second radar units and a processer, the radar units each comprising: first and second antennas, aligned in a first direction, and offset in a second, orthogonal, direction, and a linear array of antennas distributed along the first direction and including the first or second antenna; wherein: the second radar unit is configured to receive, at is second antenna, a first signal, being a reflection, from a target, of a first FMCW signal transmitted by the first radar unit first antenna; the first radar unit is configured to receive, at its second antenna, a second signal, being a reflection, from the target, of a second FMCW signal transmitted by the second radar unit first antenna; and the processor is configured to estimate phase noise from the first signal and the second signal.