FMCW Radar Phase Calibration Using Direct Crosstalk

Solution Overview

Problem

MIMO radar systems face challenges in accurately calibrating and monitoring the phase shifts of radar signals emitted via different channels due to unavoidable tolerances and cross-sensitivities, which affect the precision of object detection and beamforming techniques.

Innovation Solution

The method involves generating frequency-modulated RF oscillator signals and using crosstalk between transmitting and receiving channels to determine phase shifts, employing a modulator to frequency-shift the LO signal, and utilizing phase shifters to set desired phase differences, with phase calibration achieved through algorithms like the RELAX algorithm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If MIMO radar systems use multiple transmitting channels to improve object detection accuracy and beamforming capability, then the measurement precision and detection capability are improved, but phase calibration becomes more difficult due to unavoidable tolerances and cross-sensitivities between channels

Engineering Contradiction:

Improvephase measurement precisionVSAvoidphase calibration difficulty

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent converts the harmful effect of direct crosstalk between transmitting and receiving channels into a beneficial calibration signal. By intentionally utilizing the crosstalk that occurs during normal operation, the system can determine phase shifts without requiring separate calibration procedures. The crosstalk signal, which was previously considered interference, becomes the basis for phase measurement and calibration.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The radar system performs self-calibration by using its own operational signals for phase measurement. The system determines phase shifts of transmitting channels by analyzing signals already present during normal radar operation, eliminating the need for external calibration equipment or separate calibration procedures. The system serves its own calibration needs using its inherent operational characteristics.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If phase calibration is performed using traditional methods with external equipment, then measurement precision can be maintained, but device complexity and calibration time increase

Engineering Contradiction:

Improvephase calibration precisionVSAvoidcalibration system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The radar system performs self-calibration by using its own operational signals for phase measurement. The system determines phase shifts of transmitting channels by analyzing signals already present during normal radar operation, eliminating the need for external calibration equipment or separate calibration procedures. The system serves its own calibration needs using its inherent operational characteristics.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The receiving channels serve dual functions: they both detect radar targets and simultaneously measure phase shifts of transmitting channels. The same hardware infrastructure used for target detection is also utilized for phase calibration, eliminating the need for separate calibration equipment and reducing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If direct crosstalk is eliminated through shielding and isolation, then signal interference is reduced, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvesignal interferenceVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent converts the harmful effect of direct crosstalk between transmitting and receiving channels into a beneficial calibration signal. By intentionally utilizing the crosstalk that occurs during normal operation, the system can determine phase shifts without requiring separate calibration procedures. The crosstalk signal, which was previously considered interference, becomes the basis for phase measurement and calibration.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the interpretation and utilization of the crosstalk parameter from a harmful interference to be eliminated into a useful signal to be measured and exploited for calibration purposes. Instead of attempting to reduce crosstalk through physical isolation, the system adjusts its signal processing approach to extract valuable phase information from the crosstalk signals.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11366199B2Phase calibration in FMCW radar systems

Publication Date: 2022.06.21 INFINEON TECHNOLOGIES AG

AI summary

A method for a radar system is described. In accordance with one example implementation, the method comprises generating a frequency-modulated RF oscillator signal and feeding the RF oscillator signal to a first transmitting channel and a second transmitting channel. The method further comprises generating a first RF transmission signal in the first transmitting channel based on the RF oscillator signal, emitting the first RF transmission signal via a first transmitting antenna, receiving a first RF radar signal via a receiving antenna, and converting the first RF radar signal to a baseband, as a result of which a first baseband signal is obtained, which has a first signal component having a first frequency and a first phase, where the first signal component is assignable to direct crosstalk from the first transmitting antenna. This procedure is repeated for the second transmitting channel.