Radar Signal Processing Mitigates Velocity Aliasing
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Solution Overview
Problem
Current FCM radar systems face limitations in setting a wide detection range and accurate measurement due to aliasing issues in distance and relative velocity, which restricts the implementation of high-resolution radar systems, especially in in-vehicle applications where hardware constraints limit sampling frequency and bandwidth.
Innovation Solution
A radar device that transmits multiple signals with different parameters to compute distances and velocities, allowing selection of measurement results based on aliasing states to achieve high accuracy, using a combination of first and second transmission signals with varying detection ranges and resolutions to mitigate aliasing effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide detection range is set in FCM radar systems, then the coverage area is improved, but aliasing occurs in distance and relative velocity measurements which degrades measurement precision
Solution Approach 1:
The patent segments the detection range into multiple sub-ranges, each with its own optimized parameters. By dividing the wide detection range into smaller segments, the system可以避免aliasing in each segment while maintaining overall wide coverage. Each segment processes measurements independently with parameters tailored to its specific range, thus preserving measurement precision across the entire wide detection range.
Solution Approach 2:
The patent dynamically adjusts transmission signal parameters (such as chirp rate, frequency sweep range) based on the detected target distance and required measurement precision. When targets are at different ranges, the system changes parameters adaptively to optimize measurement accuracy for each scenario, preventing aliasing while maintaining wide detection capability.
2Measurement precision
If high-resolution measurement is implemented, then measurement precision is improved, but hardware constraints limit sampling frequency and bandwidth which degrades system reliability
Solution Approach 1:
The patent changes key parameters of the transmission signal (chirp duration, bandwidth, sweep rate) to achieve high measurement precision without requiring excessive sampling frequency. By optimizing these parameters within hardware constraints, the system achieves high-resolution measurements while maintaining reliable operation with available hardware capabilities.
Solution Approach 2:
The patent uses periodic transmission of chirp signals with optimized duty cycles and repetition intervals. By carefully designing the periodic structure of transmitted signals, the system achieves high measurement precision while working within sampling frequency limitations, ensuring reliable periodic measurements without overwhelming hardware constraints.
3Measurement precision
If multiple transmission signals with different parameters are used, then measurement accuracy is improved by mitigating aliasing, but device complexity increases
Solution Approach 1:
The patent designs a multi-functional signal processing framework that handles multiple transmission signal types through a unified processing architecture. The same hardware and software infrastructure processes different chirp signals with varying parameters, reducing overall system complexity despite using diverse transmission signals for aliasing mitigation.
Solution Approach 2:
The patent uses simplified models and lookup tables that replicate complex aliasing behavior patterns. Instead of implementing full complex signal processing for each scenario, the system uses pre-computed copies of aliasing characteristics to quickly determine optimal parameter selections, reducing processing complexity while maintaining high measurement accuracy.
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 enables high-accuracy measurement results by determining the state of aliasing and selecting measurement values from multiple parameters, effectively overcoming the limitations of aliasing in FCM systems and achieving performance comparable to FM-CW systems.
Implementation Method 1
a radar device configured to: transmit a transmission signal; obtain reception signals which are reflected waves of the transmission signal from a target
Implementation Method 2
a mixer configured to compute a difference between the reception signal and the transmission signal, thereby obtaining a beat signal
Implementation Method 3
an A/D converter configured to A/D convert the beat signal obtained by the mixer, thereby obtaining a digital signal
Implementation Method 4
obtains the differences between each of the reception signals and the transmission wave, thereby obtaining beat signals, and performs two-dimensional FFT (Fast Fourier Transform) on the beat signals, thereby obtaining the distance and relative velocity
Implementation Method 5
the FCM system detects a Doppler frequency between the beat signals, using phase change attributable to the Doppler frequency, thereby computing the relative velocity
Data Source
AI summary
There is provided a radar device. A transmitting unit transmits a first transmission signal generated based on a first parameter for computing a relative velocity or a distance in a first detection range, and a second transmission signal generated based on a second parameter for computing a relative velocity or a distance in a second detection range narrower than the first detection range. A receiving unit receives first and second reception signals from a target. A measuring unit computes a first relative velocity or a first distance in the first detection range based on the first reception signals, and compute a second relative velocity or a second distance in the second detection range based on the second reception signals, and selects any one of the first and second relative velocities, or any one of the first and second distances, as the result of measurement.