Radar Phase Rotation Pattern for DC Offset Cancellation
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Solution Overview
Problem
Radar detection performance is degraded due to circuit errors such as IQ mismatch, DC offsets, and phase noise in radar apparatuses, particularly when detecting weak reflection waves from pedestrians, which are overwhelmed by noise levels, leading to reduced detection ratios and performance deterioration.
Innovation Solution
The radar apparatus incorporates a phase rotation controller that randomly varies the phase rotation pattern every transmission cycle, with the transmitter applying a first phase rotation and the receiver applying an opposite phase rotation to the reflection wave, effectively canceling out DC offset components and suppressing noise levels without the need for high-precision correction circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse-compression radar uses complementary codes to achieve low range sidelobes, then detection capability for weak targets is improved, but circuit errors such as IQ mismatch, DC offsets, and phase noise degrade radar detection performance
Solution Approach 1:
The patent applies dynamics by making the phase rotation pattern time-varying rather than fixed. The phase rotation controller randomly varies the phase rotation pattern every transmission cycle, transforming the static circuit error compensation into a dynamic process that adapts to changing conditions and prevents error accumulation.
Solution Approach 2:
The patent changes the phase rotation parameter dynamically. By randomly varying the phase rotation amount and pattern over time, the system transforms fixed parameter errors into variable parameters, causing circuit errors to average out over multiple transmission cycles and thereby suppressing their degrading effect on detection performance.
2Reliability
If the radar transmitter and receiver use fixed phase rotation patterns, then circuit errors accumulate and degrade detection performance, but implementing high-precision correction circuits increases device complexity
Solution Approach 1:
The system performs self-correction by having the receiver apply the opposite phase rotation to the transmitted signal. This self-service mechanism automatically compensates for circuit errors without requiring external intervention or complex correction circuits, as the system uses its own transmitted signal characteristics to cancel errors.
Solution Approach 2:
The patent converts harmful fixed phase errors into beneficial random phase variations. By intentionally introducing random phase rotation patterns, the system transforms what would be harmful fixed errors into beneficial error-suppressing variations that average out over time, turning the problem of phase stability into a solution for error cancellation.
3Adaptability or versatility
If the radar detects weak reflection waves from pedestrians, then detection coverage is improved, but noise levels overwhelm the weak signals leading to reduced detection ratios
Solution Approach 1:
The patent applies periodic action through repeated transmission cycles with varying phase patterns. By performing multiple transmission cycles with different random phase rotation patterns and combining the results, the system leverages periodic repetition to suppress noise and enhance weak periodic signals from pedestrians above random noise.
Solution Approach 2:
The system maintains continuous detection through multiple transmission cycles. Rather than single-shot detection, the radar performs continuous measurements over multiple cycles with varying phase patterns, ensuring that useful signal information accumulates while random noise averages out, maintaining detection capability throughout the measurement process.
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 inhibits the degradation of radar detection performance by whitening residual DC offset components in the Doppler frequency region, reducing noise levels and maintaining detection accuracy even with transmission DC offsets and Doppler fluctuations, thus simplifying the radar apparatus configuration.
Implementation Method 1
a phase rotation controller which randomly varies a pattern of a phase rotation amount every period corresponding to a plurality of transmission cycles, the pattern being to be applied to the radar signal within a period; and a transmission phase rotator which assigns a first phase rotation to the radar signal in accordance with the pattern
Data Source
AI summary
A radar apparatus includes a radar transmitter that transmits a radar signal in a predetermined transmission cycle and a radar receiver that receives a reflection wave signal being a reflection of the radar signal on a target. The radar transmitter includes a phase rotation controller that randomly varies a pattern of a phase rotation every period corresponding to a plurality of transmission cycles, the pattern being to be applied to the radar signal within a period, and a transmission phase rotator that assigns a first phase rotation to the radar signal in accordance with the pattern. The radar receiver includes a reception phase rotator that assigns a second phase rotation in a direction opposite to a direction of the first phase rotation to the reflection wave signal in accordance with the pattern.