Doppler Radar Ambiguity Resolution Using Dual Repetition Rates
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Solution Overview
Problem
Automotive radar systems face ambiguity in measuring the radial distance and relative radial velocity due to uniform sampling with a fixed frequency, leading to aliasing and errors in range and velocity calculations, especially when multiple reflectors are present.
Innovation Solution
The method involves transmitting two sequences of waveforms with different repetition rates, downconverting and processing the received signals to create range/relative velocity matrices, and interpolating these matrices to align frequency samples, allowing for the determination of true velocities through logical operations on unfolded detection vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform sampling with a fixed frequency is used, then the radar system structure is simple, but aliasing occurs leading to measurement ambiguity in range and velocity
Solution Approach 1:
The patent combines multiple radar signals with different repetition rates (first and second transmit signals) to simultaneously resolve range and velocity ambiguities. By merging the information from these different sampling rates, the system achieves unambiguous measurements without requiring overly complex individual signal processing chains for each parameter.
Solution Approach 2:
The patent transitions from single-dimension uniform sampling to multi-dimensional sampling by introducing a second time dimension with a different repetition rate. This allows the system to resolve ambiguities that cannot be solved within a single sampling dimension, effectively adding temporal diversity to the measurement process.
2Measurement precision
If different waveform repetition rates are used, then unambiguous measurement range is improved, but signal processing complexity increases
Solution Approach 1:
The patent dynamically adjusts the repetition rates of the transmit signals to optimize the unambiguous measurement range for different operational scenarios. The system can adaptively change the repetition rates based on the expected velocity and range of targets, allowing flexible optimization without fixed hardware constraints.
Solution Approach 2:
The patent replaces complex hardware-based ambiguity resolution mechanisms with signal processing algorithms. Instead of using multiple physical radar systems or complex switching networks, the invention uses digital signal processing to combine and analyze signals from different repetition rates, reducing hardware complexity while maintaining measurement accuracy.
3Quantity of substance
If multiple reflectors are present, then detection capability is improved, but aliasing errors increase making velocity determination difficult
Solution Approach 1:
The patent segments the velocity determination process by first resolving range ambiguities using the different repetition rates, then using the resolved range information to accurately determine velocities even in the presence of multiple reflectors. This segmentation allows the system to handle multiple targets without the velocity determination being corrupted by aliasing errors.
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
This approach enhances the unambiguous measurement range and accuracy of radial distance and relative velocity, reducing errors caused by aliasing and improving the detection of multiple reflectors by aligning frequency samples and performing logical operations on detection vectors.
Implementation Method 1
Radar systems may be used to detect the range and velocity of nearby targets
Data Source
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AI summary
Various exemplary embodiments relate to a method for determining the velocity of an object using radar system having a processor, including: receiving, by a processor, a first digital signal corresponding to a first transmit signal; receiving, by the processor, a second digital signal corresponding to a second transmit signal; processing the first digital signal to produce a first range / relative velocity matrix; detecting objects in the first range / relative velocity matrix to produce a first detection vector; unfolding the first detection vector; processing the second digital signal to produce a second range / relative velocity matrix; interpolating the second range / relative velocity matrix in the relative velocity direction wherein the interpolated second range / relative velocity matrix has a frequency spacing corresponding to the frequency spacing of the first range / relative range velocity matrix in the relative velocity direction; detecting objects in the second range / relative velocity matrix to produce a second detection vector; unfolding the second detection vector; and determining a true velocity of the detected objects based upon the unfolded first and second detection vectors.