Radar Transceiver Phase Noise Cancellation for FMCW Detection
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Solution Overview
Problem
FMCW radar systems face challenges in accurately detecting radar targets due to phase noise caused by short-range leakage, which degrades signal detection quality and limits the sensitivity of distance measurements, especially when the radar transceiver's RF frontend is integrated into a monolithic microwave integrated circuit (MMIC).
Innovation Solution
The method involves generating an RF oscillator signal with phase noise, applying it to an artificial radar target with circuitry that applies a delay and gain, and then modulating the resulting signal to cancel out the frequency-shifted noise in the RF domain, using an RF subtractor circuit to eliminate the phase noise from the received radar signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the RF frontend is integrated into a monolithic microwave integrated circuit (MMIC), then device complexity is reduced and manufacturing is simplified, but phase noise from short-range leakage increases and degrades signal detection quality
Solution Approach 1:
The patent generates an artificial short-range leakage signal that mimics the harmful phase noise, then subtracts it from the received signal. This converts the harmful phase noise effect into a beneficial cancellation process, where the artificial signal serves as a reference to eliminate the actual harmful leakage through adaptive noise cancellation.
Solution Approach 2:
The patent introduces an artificial radar target as an intermediary element that generates a reference signal representing the short-range leakage. This intermediary signal acts as a mediator between the harmful phase noise and the cancellation process, enabling the system to model and subtract the noise without directly manipulating the harmful signal itself.
2Power
If short-range targets reflect the transmitted radar signal with high amplitude, then the reflected signal strength increases, but phase noise dominates the noise floor and limits detection sensitivity
Solution Approach 1:
The patent converts the harmful high-amplitude phase noise from short-range targets into a useful reference signal by generating an artificial echo with matching characteristics. This artificial signal, when subtracted from the received signal, eliminates the phase noise dominance and restores detection sensitivity, turning the harmful high-amplitude reflection into a beneficial cancellation reference.
Solution Approach 2:
The patent applies preliminary anti-action by generating and subtracting the artificial leakage signal before the harmful phase noise can dominate the noise floor. This preemptive cancellation prevents the phase noise from degrading detection sensitivity, addressing the problem before it manifests in the final detection process.
3Length of moving object
If the pulse length is reduced to measure short distances, then the distance measurement capability improves, but the energy contained in the pulse decreases making detection impossible
Solution Approach 1:
The patent employs continuous-wave frequency-modulated (FMCW) radar operation instead of pulsed radar, using periodic frequency modulation of a continuous signal. This periodic action allows energy to be distributed over time in a continuous manner, maintaining sufficient energy for detection while enabling precise short-distance measurement through frequency analysis of the reflected continuous wave.
Solution Approach 2:
The patent changes the fundamental operating parameter from pulsed time-domain operation to continuous frequency-domain operation. By modulating the frequency of a continuous wave and analyzing the beat frequency between transmitted and received signals, the system achieves short-distance measurement capability without sacrificing pulse energy, as the continuous wave maintains constant power levels.
Data Source
AI summary
A method for cancelling phase noise in a radar signal is described herein. In accordance with one embodiment, the method includes transmitting an RF oscillator signal, which represents a local oscillator signal including phase noise, to a radar channel and receiving a respective first RF radar signal from the radar channel. The first RF radar signal included at least one radar echo of the transmitted RF oscillator signal. Further, the method includes applying the RF oscillator signal to an artificial radar target composed of circuitry, which applies a delay and a gain to the RF oscillator signal, to generate a second RF radar signal. The second RF radar signal is modulated by a modulation signal thus generating a frequency-shifted RF radar signal. Further, the method includes subtracting the frequency-shifted RF radar signal from the first RF radar signal.