Vehicle Radar Chirp Phase Ranging for Higher Range Resolution
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Solution Overview
Problem
Radar devices using the binary CW system face limitations in range resolution due to the use of window functions in fast Fourier transform, which fail to separate adjacent frequency bins effectively, and are unable to measure distances from targets with the same relative velocity or stationary targets.
Innovation Solution
A radar device that generates transmission waves with first and second chirp signals of different frequencies, estimates phase differences using a predetermined algorithm, and calculates distances based on these phase differences and frequency differences to improve range resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a window function is used in preprocessing of fast Fourier transform on a reflected signal, then the processing is simplified and computation is easier, but the range resolution degrades and adjacent frequency bins cannot be separated
Solution Approach 1:
The patent extracts and removes the window function preprocessing step from the signal processing chain. By directly applying fast Fourier transform to the reflected signal without window function multiplication, the method eliminates the resolution degradation caused by windowing while maintaining computational simplicity.
Solution Approach 2:
Instead of applying a window function to reduce spectral leakage before FFT (conventional approach), the patent inverts the approach by skipping the window function entirely and using alternative signal processing techniques to achieve the same spectral analysis goals without the resolution penalty.
2Adaptability or versatility
If the binary CW system is used to estimate distance from stationary or slow-moving targets, then the Doppler effect limitation is avoided, but the range resolution degrades due to window function requirements
Solution Approach 1:
The patent removes the window function preprocessing step from the binary CW system signal processing, eliminating the resolution degradation that previously accompanied the use of window functions when measuring stationary or slow-moving targets.
Solution Approach 2:
The patent changes the signal processing parameters by eliminating the window function application, thereby altering the frequency domain characteristics to achieve improved range resolution while maintaining the ability to measure targets across a wide velocity range including stationary objects.
3Ease of manufacture
If FMCW system is used with limited frequency modulation bandwidth, then the system is easier to implement, but the range resolution is limited by the available frequency bands
Solution Approach 1:
The patent segments the frequency analysis into multiple discrete frequency bins through direct FFT processing without window function smearing. This segmentation approach allows precise identification of frequency components corresponding to different target distances, improving range resolution while maintaining implementation simplicity.
Solution Approach 2:
The patent applies partial action by using only the essential FFT processing without the additional window function step, achieving sufficient spectral analysis for improved range resolution while avoiding the excess processing that degrades performance.
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
The radar device achieves enhanced range resolution, enabling accurate distance measurement from targets with varying relative velocities, including stationary targets, and reduces interference from other radar devices.
Implementation Method 1
A radar device according to an aspect of the present disclosure includes a transmitter that generates, as a transmission wave, an electromagnetic-wave beam
Implementation Method 2
receiving a reflected wave obtained by reflecting the transmission wave from a target
Implementation Method 3
The binary CW system, which uses the Doppler effect, is not applied to a target having the same relative velocity or a stationary target
Data Source
AI summary
A radar device includes a transmitter that generates, as a transmission wave, an electromagnetic-wave beam including a first chirp signal and a second chirp signal, the first chirp signal being a chirp signal whose frequency changes from a first frequency with time, and the second chirp signal being a chirp signal whose frequency changes, with time, from a second frequency different from the first frequency An antenna transmits the transmission wave and receives a reflected wave obtained by reflecting the transmission wave from a target. Circuitry is configured to estimate a first distance, which is a distance to the target, based on a signal related to the reflected wave, estimate a phase difference for the first distance, and estimate a second distance, which is a distance to the target, based on the phase difference and a difference between the first frequency and the second frequency.