Radar Doppler Precoding for Close Target Separation
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Solution Overview
Problem
In vehicle radar systems, high reflectivity targets can mask lower reflectivity targets due to limited filter bandwidth, making it difficult to distinguish and separate close targets based on their Doppler frequencies.
Innovation Solution
A method and system that transmit a pulse sequence and detect targets based on their Doppler frequencies, followed by generating a nulling pulse sequence to cancel the reflections of the detected high reflectivity target, allowing the detection of lower reflectivity targets by forming a matrix of received sequences and using a binary vector to determine the nulling pulse sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a limited bandwidth filter is used to capture Doppler frequencies based on limited integration time, then the radar system can operate with limited integration time, but high reflectivity targets mask lower reflectivity targets that are close in position and speed
Solution Approach 1:
The patent segments the target detection process into multiple phases: initial detection phase and refined detection phase. In the refined phase, a nulling pulse sequence is generated specifically to cancel the signal from the high reflectivity target, allowing separate detection of lower reflectivity targets in the same Doppler frequency bin. This segmentation enables both time efficiency and improved target separation precision.
Solution Approach 2:
The patent extracts and removes the dominant high reflectivity target signal from the composite radar return by generating a nulling pulse sequence that creates a null at the detected target's Doppler frequency. This extraction isolates the masking effect, allowing the previously obscured lower reflectivity targets to be detected separately.
2Measurement precision
If integration time is increased to improve filter bandwidth and capture more Doppler frequencies, then target separation capability improves, but the radar system requires longer integration time
Solution Approach 1:
The patent performs preliminary detection to identify high reflectivity targets before conducting refined detection. By detecting and nulling these dominant targets first, the system prepares the signal environment for subsequent detection of lower reflectivity targets, avoiding the need for extended integration time to resolve all targets simultaneously.
Solution Approach 2:
The nulling pulse sequence acts as an intermediary that mediates between the high reflectivity target signal and the lower reflectivity target detection. It creates a frequency null that blocks the dominant signal path, allowing the weaker target signals to pass through and be detected without requiring increased integration time.
3Ease of operation
If the radar system uses standard pulse sequences for target detection, then the system operation is simple, but high reflectivity targets mask lower reflectivity targets
Solution Approach 1:
The patent transitions from static pulse sequences to dynamic adaptive pulse sequences. The nulling pulse sequence is dynamically generated based on real-time detection of high reflectivity targets, adapting the transmission waveform to current environmental conditions. This dynamic approach maintains operational simplicity while dramatically improving target detection accuracy.
Solution Approach 2:
The patent changes the parameters of the transmitted pulse sequence by generating a nulling version with modified spectral characteristics. The nulling pulse sequence has a null at the Doppler frequency of the high reflectivity target, changing the frequency domain parameters to enable separation of closely spaced targets with different reflectivities.
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
Enables the separation of close targets by effectively canceling the masking effect of high reflectivity targets, allowing the detection of lower reflectivity targets that were previously obscured, improving the radar system's ability to distinguish between targets with different reflectivities.
Implementation Method 1
When the target is in motion, the received pulses resulting from incremental transmitted pulses exhibit a phase change. This phase change corresponds with a frequency change referred to as the Doppler frequency.
Data Source
AI summary
A system and method to separate close targets includes transmitting a pulse sequence and detecting a first target at a first target Doppler frequency based on processed received reflections resulting from the pulse sequence. A nulling pulse sequence designed to null the processed received reflections at the target Doppler frequency is transmitted.