Radar Interference Rejection via Phase Change Detection
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Solution Overview
Problem
Conventional interference rejection methods for pulse compression radar struggle to detect radar interference signals when they are superimposed over echo signals, especially when there is little difference in amplitude or phase between the interference and echo signals.
Innovation Solution
A radar interference rejection device and method that calculates change amounts in amplitude and phase of received signals across multiple sweeps, using a change amount calculator and detector to identify variance and detect interference signals even when they are superimposed over echo signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional interference rejection methods are used that compare amplitude values across multiple sweeps, then interference signals with sufficiently greater amplitude than echo signals can be detected, but interference signals superimposed over echo signals with little amplitude difference cannot be detected
Solution Approach 1:
The patent changes the detection parameter from amplitude comparison to phase change amount comparison. By calculating the phase change amount between adjacent sweeps and comparing it across multiple sweeps, the system can detect interference signals even when their amplitude is similar to echo signals, as interference signals exhibit different phase characteristics. This parameter transformation resolves the contradiction by enabling detection in previously undetectable signal conditions.
Solution Approach 2:
Instead of directly comparing signal amplitudes to detect interference, the patent inverts the approach by comparing the change amounts of phase values across sweeps. This indirect detection method through phase change comparison allows the system to identify interference signals that would be invisible to direct amplitude comparison, thereby expanding detection capability to include superimposed signals with similar amplitudes.
2Measurement precision
If pulse compression radar is used to increase signal-to-noise ratio, then echo signal detection is improved, but interference signals are expanded to the same time width making rejection more difficult
Solution Approach 1:
The patent performs interference rejection processing before matched filter processing. By detecting and rejecting interference signals in the time domain before pulse compression, the system prevents interference from being expanded by the matched filter. This preliminary action maintains the signal-to-noise ratio improvement from pulse compression while avoiding the complexity of post-compression interference rejection.
Solution Approach 2:
The patent extracts and removes interference signals from the received signal before further processing. By identifying interference components through phase change comparison and eliminating them prior to matched filter processing, the system prevents interference expansion while preserving the echo signal's pulse compression benefits, thereby simplifying overall interference rejection complexity.
3Object-affected harmful factors
If interference rejection processing is applied before matched filter processing, then interference signal expansion is prevented, but both interference and echo signals are changed causing distortion in MF output
Solution Approach 1:
The patent introduces phase change amount calculation as an intermediary detection mechanism. Instead of directly manipulating signal amplitudes or phases in a way that distorts the signal, the system uses phase change comparison as an intermediate step to identify interference, then applies targeted rejection only to detected interference components. This intermediary approach prevents interference expansion while minimizing distortion to echo signals.
Solution Approach 2:
The patent applies interference rejection selectively to specific time domains where interference is detected through phase change comparison, rather than uniformly processing all signal portions. By identifying precise interference locations and applying rejection only there, the system prevents interference expansion while preserving the local quality and fidelity of echo signals in non-interference regions.
Data Source
AI summary
An interference rejection device includes a change amount calculator, a detector, and a rejecter. The change amount calculator is configured to find change amounts in at least one of amplitude and phase of received signals of a plurality of sweeps in a distance direction between a first distance and a second distance. The detector is configured to detect radar interference occurring between the first distance and the second distance by comparing the change amounts calculated by the change amount calculator between the plurality of sweeps. The rejecter is configured to reduce the amplitude of the received signal corresponding to a position of the radar interference.