Radar Phase Calibration Using Marker Back-Scatter
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Solution Overview
Problem
Modern radar systems with multiple input and multiple output (MIMO) channels face challenges in phase calibration, particularly when using distributed monolithic microwave integrated circuits (MMICs), which affect the accuracy of angle measurements.
Innovation Solution
A method and system for calibrating radar systems involving a master radar chip that generates and distributes an RF oscillator signal to phase shifters, which are used to adjust the phase shifts of RF signals radiated by slave radar chips, ensuring the phases match a predefined phase-over-antenna-position characteristic by using a marker with a predetermined position for back-scattered signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase calibration is performed in MIMO radar systems with distributed MMICs, then angle measurement accuracy is improved, but system complexity and calibration difficulty increase
Solution Approach 1:
A marker with known position is introduced as an intermediary target to facilitate phase calibration. The marker serves as a reference object that enables the system to measure and adjust phase differences across multiple MMICs by providing a known reflection point, thereby simplifying the calibration process while maintaining measurement precision.
Solution Approach 2:
The system uses phase-shifted oscillator signals to create virtual copies of the transmitted signal at different phase states. By comparing the received signals from multiple MMICs against these known phase-shifted references, the system can determine and correct phase errors without requiring complex calibration hardware.
2Stability of the object's composition
If multiple phase-shifted oscillator signals are used for calibration, then phase coherence across MMICs is improved, but signal distribution complexity increases
Solution Approach 1:
The calibration signal is segmented into multiple phase-shifted versions that are distributed to different MMICs. Each MMIC receives a specific phase-shifted oscillator signal, allowing independent phase calibration of each channel while maintaining overall system coherence. This segmentation approach simplifies the distribution architecture compared to requiring full signal interconnection.
Solution Approach 2:
The system changes the phase parameter of the oscillator signal to create multiple calibration signals. By systematically varying the phase shift applied to the oscillator signal, the system generates a set of reference signals with known phase relationships, enabling coherent calibration across all MMICs without complex signal routing.
3Measurement precision
If phase calibration is performed using back-scattered signals from a marker, then calibration precision is improved, but calibration time increases
Solution Approach 1:
The calibration process uses periodic transmission of phase-shifted oscillator signals toward the marker. By transmitting signals in periodic sequences with different phase shifts and measuring the back-scattered responses, the system efficiently extracts phase calibration data through repeated measurements, balancing precision requirements with acceptable calibration time.
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 enables precise calibration of phases in MIMO radar systems, improving the accuracy of angle measurements and maintaining coherence across multiple MMICs, thus enhancing the overall performance of the radar system.
Implementation Method 1
distribute the RF oscillator signal to a plurality of phase shifters, which are configured impose a phase shift to the RF oscillator signal
Implementation Method 2
The radiated signal is back-scattered at a marker, which has a predetermined position relative to the antennas coupled to the radar chips
Implementation Method 3
generating a plurality of base-band signals by down-converting, in the at least one RF input channel of each radar chip, the received signals into a base band using the phase-shifted RF oscillator signals received by the respective radar chips
Data Source
AI summary
A method for calibrating a radar system includes generating an RF oscillator signal and distributing the RF oscillator signal to a plurality of phase shifters each providing a respective phase-shifted RF oscillator signal; receiving the phase-shifted RF oscillator signals by corresponding radar chips and radiating the phase-shifted RF oscillator signal via a first RF output channel of a first one of the radar chips; receiving a back-scattered signal by at least one RF input channel of each radar chip and generating a plurality of base-band signals by down-converting the received signals into a base band using the phase-shifted RF oscillator signals received by the corresponding radar chips; determining a phase for each base-band signal; and adjusting the phase shifts caused by the phase shifters such that the phases of the base-band signals match a predefined phase-over-antenna-position characteristic.