Radar Apparatus IQ Imbalance Correction via Phase Shifter
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Solution Overview
Problem
Pulse-compression radar systems face performance degradation due to circuit errors such as IQ mismatch and phase noise, which affect the detection of weak reflection waves from pedestrians, leading to false detection and reduced radar detection performance.
Innovation Solution
The radar system incorporates a phase shifter that applies a predetermined phase shift to the transmission codes to correct modulated code imbalances, ensuring that code imbalances are evenly distributed across all four quadrants of the IQ plane, thereby smoothing IQ errors and reducing the impact of circuit errors on radar detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse-compression radar transmits complementary codes to achieve low range sidelobes, then detection resolution is improved, but circuit errors such as IQ mismatch cause false detection and performance degradation
Solution Approach 1:
The system performs preliminary action by transmitting a test signal before actual radar operation to measure IQ imbalance in advance. The measured imbalance characteristics are stored and used for subsequent correction during radar detection, preventing performance degradation before it occurs
Solution Approach 2:
The system implements feedback by measuring the actual IQ imbalance of the circuit and using this measured information to correct the radar signal processing. The correction amount is determined based on the measured imbalance, creating a closed-loop system that adapts to actual circuit conditions
2Measurement precision
If the radar receiver uses a wide dynamic range to detect weak pedestrian reflection waves, then detection sensitivity is improved, but circuit errors still cause false peaks and detection accuracy decreases
Solution Approach 1:
The system introduces an intermediary correction process between signal reception and detection. A complex conjugate multiplication is applied as an intermediary operation to correct IQ imbalance effects before the final detection decision, eliminating false peaks caused by circuit errors
Solution Approach 2:
The system replaces physical hardware perfection requirements with signal processing correction. Instead of requiring perfectly matched IQ circuits, the patent uses digital signal processing (complex conjugate multiplication) to compensate for circuit imperfections, substituting mechanical precision with computational correction
Data Source
AI summary
A radar apparatus includes: a radar transmitter transmitting a radar signal; and a radar receiver receiving a reflection wave signal being a reflection of the radar signal on a target. The radar transmitter includes: a radar transmission signal generator that generates the radar signal composed of a transmission code with each sub-pulse given a predetermined phase shift; and a transmission radio unit that transmits the radar signal generated by the radar transmission signal generator in a predetermined transmission cycle. In radar signals transmitted by the transmission radio unit in a predetermined number of transmission cycles, code imbalances of transmission codes are included in all of four quadrants of the IQ plane. Each of the code imbalances is an imbalance between the positions where a plurality of sub-pulses constituting a transmission code included in a radar signal transmitted in each of the transmission cycles are mapped on the IQ plane.