Radar Receiver Nonlinearity Compensation for Intermodulation Suppression
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Solution Overview
Problem
Radar sensor devices suffer from nonlinearities in components like mixers and amplifiers, which adversely affect measurement accuracy, particularly in MIMO systems used for advanced driver-assistance systems and autonomous driving.
Innovation Solution
A radar device with a receiving channel that includes a mixer and a test signal generator to generate a test signal, allowing for the determination of intermodulation products and characterization of nonlinearity, followed by suppression of these products in the digital output signal using a signal processing unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If nonlinear components (mixers, amplifiers) are used in the receiving channel, then the radar device can perform signal processing functions, but intermodulation products are generated that degrade measurement accuracy
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by using test signals to deliberately generate intermodulation products in a controlled manner during a first mode of operation. These harmful intermodulation products are then used to characterize the nonlinearity of the receiving channel and compute compensation parameters. In the second mode, these same nonlinearity characteristics are used to suppress intermodulation products in the actual radar measurements, thereby converting the harmful effect into a beneficial calibration mechanism that improves measurement accuracy.
Solution Approach 2:
The patent implements feedback by measuring the intermodulation products generated from test signals and using these measurements to adjust the signal processing. The signal processing unit determines parameters characterizing the nonlinearity from the intermodulation products and uses these parameters to suppress intermodulation distortion in subsequent radar measurements, creating a closed-loop system that continuously compensates for nonlinearities.
2Measurement precision
If a test signal is fed into the receiving channel to characterize nonlinearity, then intermodulation products can be determined and compensation parameters obtained, but the normal radar measurement function is interrupted
Solution Approach 1:
The patent applies segmentation by dividing the operation into distinct temporal modes: a first mode for characterizing nonlinearity using test signals, and a second mode for performing normal radar measurements with compensation. This temporal segmentation allows the system to switch between calibration and measurement functions, enabling accurate nonlinearity characterization without permanently interrupting radar measurement capabilities.
Solution Approach 2:
The patent implements periodic action by alternating between the first mode (nonlinearity characterization using test signals) and the second mode (normal radar measurement). This periodic switching allows the system to periodically update the nonlinearity compensation parameters while maintaining continuous radar measurement capability, balancing accuracy with productivity.
3Measurement precision
If intermodulation products are suppressed in the digital output signal, then measurement accuracy improves, but additional signal processing steps are required
Solution Approach 1:
The patent applies preliminary action by performing nonlinearity characterization using test signals before actual radar measurements are taken. The compensation parameters are determined in advance during the first mode, so that when normal measurements occur in the second mode, the suppression of intermodulation products can be performed using pre-computed parameters, reducing the real-time processing burden.
Solution Approach 2:
The patent uses parameter changes by determining specific parameters (such as Taylor series coefficients) that characterize the nonlinearity of the receiving channel. These parameters are then used to modify the signal processing algorithm, transforming the nonlinear distortion into a correctable effect through mathematical modeling and compensation, thereby improving accuracy without requiring complete redesign of the signal processing chain.
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
Improves radar measurement accuracy by effectively suppressing intermodulation distortion, enhancing the signal-to-interference ratio and enabling precise detection and localization of radar targets.
Implementation Method 1
a mixer (104), which is configured to generate a baseband signal from an RF input signal by mixing with a local oscillator signal
Data Source
AI summary
This description relates to a method for suppressing intermodulation distortion in a digital output signal of a radar device. In one implementation, the method includes—in a first mode—feeding a test signal into a receiving channel, the test signal is fed to a mixer contained in the receiving channel and is downconverted to a baseband, a baseband signal that includes intermodulation products on account of a nonlinearity of the transfer characteristic of the receiving channel being provided at the mixer output. The digital output signal is generated based on the baseband signal. The method further includes—in the first mode—determining an intermodulation product and, on the basis thereof, ascertaining a parameter of a model characterizing the nonlinearity. In a second mode, in which an antenna signal is fed to the mixer—suppressing the intermodulation product in the digital output signal based on the parameter and the baseband signal.