FMCW Radar Nonlinearity Calibration via Delayed Signal Mixing
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Solution Overview
Problem
Frequency-modulated continuous wave (FMCW) radar systems face performance degradation due to nonlinearity in the frequency sweep of the transmitted waveform, particularly at close ranges where the nonlinearity in the instantaneous frequency affects the accuracy of distance measurement.
Innovation Solution
A mechanism is introduced to estimate and compensate for the nonlinearity in the radar signal by using a delay generator to create a delayed radar signal, which is mixed with the original signal to generate an estimate of the nonlinearity. This estimate is then used to adjust the received signal to approach the ideal waveform, improving the accuracy of distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear frequency modulated waveform is used for distance measurement, then the measurement range is extended, but nonlinearity in the frequency sweep degrades measurement precision
Solution Approach 1:
The patent applies preliminary action by measuring the nonlinearity of the frequency sweep before actual distance measurement. A calibration signal is transmitted and the nonlinearity characteristics are determined in advance. This pre-measured nonlinearity data is then used to correct subsequent distance measurements, eliminating the need for real-time nonlinearity compensation during operation.
Solution Approach 2:
The patent implements feedback by using the measured nonlinearity characteristics to adjust and correct the distance measurement process. The system continuously monitors the frequency sweep nonlinearity through calibration signals and feeds this information back to compensate for measurement errors in real-time operations, ensuring accurate distance measurement despite waveform imperfections.
2Length of stationary object
If FMCW radar is used for short-range applications, then close-range detection capability is improved, but nonlinearity effects become more severe
Solution Approach 1:
The patent applies local quality by implementing nonlinearity correction specifically tailored for short-range detection scenarios. The calibration process characterizes the nonlinearity at different frequency points and time intervals, allowing the system to apply appropriate correction factors for close-range measurements where nonlinearity has the most significant impact on accuracy.
3Length of stationary object
If a pulsed radar is used for far-range detection, then long-distance capability is achieved, but close-range detection performance deteriorates
Solution Approach 1:
The patent implements universality by making the FMCW radar system capable of accurate operation across both short and long ranges. Through the nonlinearity calibration and correction mechanism, the system achieves multi-functional performance - it can detect close-range objects with high precision while maintaining the extended detection range capability of FMCW radar, effectively combining the advantages of both pulsed and FMCW approaches.
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
The compensation method effectively reduces performance degradation caused by nonlinearity, enhancing the accuracy of distance, velocity, and direction detection in FMCW radar systems, especially in short-range applications like automotive radar and gesture recognition.
Implementation Method 1
The transmitted signal is combined with the received signal in a mixer to provide an indication of a frequency difference between the transmitted signal and the received signal
Implementation Method 2
A delay generator is coupled to the waveform generator to receive the radar signal that is directed to the transmitter antenna and to provide a delayed radar signal
Data Source
AI summary
Various embodiments include methods and systems having a frequency-modulated continuous wave radar operable to compensate a return signal for nonlinearity in the associated radar signal that is transmitted. The radar signal can be mixed with a delayed version of the radar signal such that the mixed signal can be used to generate an estimate of the nonlinearity. The estimate can be used to compensate the return signal from an object that reflects the associated transmitted radar signal. Additional apparatus, systems, and methods can be implemented in a variety of applications.