Multi-Transmitter Radar Phase Calibration Under Drift
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Solution Overview
Problem
Existing radar systems face challenges in accurately calibrating multiple transmitters due to drifting phase errors over time, which degrade performance, especially in advanced automotive radar systems requiring higher angular resolution.
Innovation Solution
A method for continuous calibration of radar transmitters involves transmitting from a single transmitter, estimating and adjusting the transmitter adjuster, and interspersing calibration cycles with operation cycles to maintain accurate transmit phase modulation, using iterative techniques to correct phase shifter errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If classical end-of-line calibration is used, then initial phase accuracy is achieved, but phase modulation accuracy degrades over time due to drift
Solution Approach 1:
The radar system performs self-calibration by using its own transmitted signals and received echoes to detect and correct phase errors. The system automatically identifies modulation artifacts in the received signals and adjusts the phase shifters to eliminate these artifacts, enabling continuous self-correction without external calibration equipment.
Solution Approach 2:
The calibration process uses feedback from the received radar signals to detect phase errors. By analyzing modulation artifacts in the range-Doppler spectrum and extracting phase error information from target echoes, the system generates correction signals that are fed back to adjust the transmitter phase shifters, creating a closed-loop control system.
2Measurement precision
If continuous calibration is performed, then phase accuracy is maintained, but system complexity increases
Solution Approach 1:
The system uses its own operational signals for calibration purposes, eliminating the need for separate calibration hardware or test equipment. The received radar echoes containing target information are reused to extract phase error data, making the calibration function self-contained and avoiding additional system complexity.
Solution Approach 2:
The calibration process leverages the same signal processing chains and hardware components used for normal radar operation. The Fast Fourier Transform processors, range-Doppler spectrum analyzers, and phase shifter control mechanisms serve dual purposes: normal target detection and calibration, thereby avoiding dedicated calibration hardware.
3Measurement precision
If multiple transmitters are used, then angular resolution is improved, but phase error drift becomes more challenging to model
Solution Approach 1:
The calibration process treats each transmitter independently by sequentially activating one transmitter at a time while keeping others inactive. This segmentation allows the system to measure and correct phase errors for each transmitter separately, avoiding the complexity of modeling interactions between multiple transmitters simultaneously.
Solution Approach 2:
The system performs preliminary calibration of each transmitter individually before multi-transmitter operation. By pre-characterizing the phase errors of each transmitter in isolation, the system establishes baseline correction values that simplify subsequent multi-transmitter phase management and reduce the complexity of error modeling.
Data Source
AI summary
A radar system has a plurality of radar transmitters and at least one radar receiver, each radar transmitter having a transmitter adjuster for tuning the output of the respective transmitter, for example tuning the phase of each of a plurality of constellation points of a constellation. The radar system may operate in a calibration cycle by transmitting from a single radar transmitter using the transmitter adjuster, obtaining an estimate of the error in the transmitter adjuster and adjusting the transmitter adjuster according to the estimate of the error. In an operation cycle the radar system may transmit using the plurality of radar transmitters, the signal being transmitter from each radar transmitter being tuned using the transmitter adjuster. Calibration cycles are interspersed between operation cycles during operation.