Automotive Radar Interference Mitigation via Pseudo-Random Chirp Hopping
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Solution Overview
Problem
Automotive radar systems face significant interference challenges when multiple unsynchronized radars operate in close proximity, leading to issues like ghost targets and reduced signal-to-noise ratios, which are critical concerns for autonomous driving applications where low failure rates are required.
Innovation Solution
A frequency modulated continuous wave (FMCW) radar sensor that employs a pseudo-random chirp frequency hopping sequence, a dedicated wideband receiver for interference detection, and adaptive signal processing techniques to mitigate interference by altering chirp sequences and ceasing transmission during interference, ensuring minimal overlap with other radar signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple unsynchronized radars operate in close proximity, then radar coverage and detection capability are improved, but mutual interference increases leading to ghost targets and reduced signal-to-noise ratio
Solution Approach 1:
The patent applies dynamics by making the radar transmission waveform flexible and adaptable rather than fixed. The system dynamically adjusts the chirp sequence based on detected interference conditions, switching between different transmission patterns to avoid interference while maintaining detection capability. This dynamic adaptation resolves the contradiction between operating multiple radars and avoiding mutual interference.
Solution Approach 2:
The patent changes transmission parameters (frequency modulation patterns, chirp sequences, timing) to avoid interference. By varying these parameters dynamically based on detected interference conditions, the system maintains reliable detection while minimizing ghost targets and signal-to-noise ratio degradation caused by mutual interference between multiple radars.
2Reliability
If radar transmission is continuous to ensure real-time detection, then detection coverage is improved, but interference with other radars increases
Solution Approach 1:
The patent implements periodic action by using pulsed or intermittent transmission patterns rather than continuous transmission. The radar transmits in periodic bursts with adjustable duty cycles, allowing other radars to operate during transmission gaps. This periodic transmission maintains real-time detection capability while reducing overall interference generated to other radar systems.
Solution Approach 2:
The system dynamically adjusts transmission timing and duration based on detected interference conditions. When interference is detected, the radar adapts its transmission pattern, reducing transmission activity during periods of high interference while maintaining detection readiness. This dynamic control resolves the contradiction between continuous transmission for real-time detection and reducing interference to other radars.
3Device complexity
If fixed chirp sequences are used for simplicity, then system complexity is reduced, but interference avoidance capability deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-defining multiple chirp sequences and interference mitigation strategies before actual operation. The system has a library of pre-programmed transmission patterns and interference response protocols that are selected based on detected conditions. This preliminary preparation enables effective interference avoidance without requiring complex real-time signal processing, thus resolving the contradiction between simplicity and interference avoidance capability.
4Measurement precision
If radar power is increased to improve signal-to-noise ratio, then detection accuracy is improved, but interference with other radars increases
Solution Approach 1:
The patent applies local quality by directing radar energy selectively toward regions of interest rather than omnidirectional high-power transmission. The system uses beamforming or directional transmission to concentrate power where needed for detection while reducing power in directions where other radars operate. This localized power distribution maintains detection accuracy while minimizing interference generated to other radar systems.
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
Effectively minimizes mutual interference between radar sensors, enhancing the reliability and accuracy of range and velocity measurements, even in high-traffic scenarios, thereby improving the safety and efficiency of autonomous driving systems.
Implementation Method 1
Typical automotive radar systems comprise a millimeter wave frequency transmitter and receiver. Each transmitter emits a millimeter wave radio signal which is reflected or scattered from surrounding objects.
Implementation Method 2
Each transmitter emits a millimeter wave radio signal which is reflected or scattered from surrounding objects. The echoes or reflections are processed by the receivers
Implementation Method 3
The Frequency Modulated Continuous Wave (FMCW) radar is a type of radar that offers more advantages compared to the others. It ensures the range and velocity information of the surrounded objects can be detected simultaneously.
Data Source
AI summary
A novel and useful radar sensor incorporating detection, mitigation and avoidance of mutual interference from nearby automotive radars. The normally constant start frequency sequence for linear large bandwidth FMCW chirps is replaced by a sequence of lower bandwidth chirps with start frequencies spanning the wider bandwidth and randomly ordered in time to create a pseudo random chirp hopping sequence. The reflected wave signal received is reassembled using the known hop sequence. To mitigate interference, the signal received is used to estimate collisions with other radar signals. If detected, a constraint is applied to the randomization of the chirps. The chirp hopping sequence is altered so chirps do not interfere with the interfering radar's chirps. Offending chirps are re-randomized, dropped altogether or the starting frequency of another non-offending chirp is reused. Windowed blanking is used to zero the portion of the received chirp corrupted with the interfering radar's chirp signal.