FMCW Radar Data Acquisition Using Bidirectional Chirp Sampling
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Solution Overview
Problem
Conventional FMCW radar systems experience high overhead time between chirp data acquisitions, leading to reduced radar update rates and poor performance due to the need to double the number of chirps for ambiguity resolution, which increases the acquisition overhead to more than half of the total acquisition time.
Innovation Solution
The method involves sampling the reflected signal in both ramping regions where the frequency of the FMCW signal ramps up and down, forming separate data streams for each, allowing for swift acquisition of chirp data and enabling faster radar update rates and improved ambiguity resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional methods are used to acquire chirp data in FMCW radar systems, then the system can obtain distance and velocity information, but the overhead time between chirp data acquisitions becomes excessively long, reducing the radar update rate
Solution Approach 1:
The patent segments the frequency modulation waveform into multiple ramping regions within a single chirp cycle. Instead of waiting for one complete chirp to finish before starting the next, the system processes multiple ramping regions (e.g., upward ramps, downward ramps, stationary regions) sequentially within the same chirp period, effectively dividing the acquisition process into exploitable segments that reduce idle overhead time.
Solution Approach 2:
The patent maintains continuous useful action by processing reflected signals from multiple ramping regions without returning to the start frequency between acquisitions. The system continuously samples and processes signals from upward ramps, downward ramps, and stationary regions in sequence, eliminating the conventional idle period where the frequency would return to the starting point, thus keeping the radar system continuously productive.
2Measurement precision
If the number of chirps is doubled for ambiguity resolution in signal processing, then the accuracy of distance and velocity measurement improves, but the total frame acquisition time doubles, increasing overhead to more than half of total acquisition time
Solution Approach 1:
The patent merges multiple types of ramping regions (upward ramps, downward ramps, stationary regions) into a single integrated acquisition process. By combining the useful signal information from all these regions within one chirp cycle, the system achieves the equivalent of multiple chirps for ambiguity resolution without actually transmitting multiple complete chirp sequences, thus halving the acquisition time while maintaining measurement precision.
Solution Approach 2:
The patent adds a temporal dimension to the frequency modulation by utilizing both upward and downward ramps within the same chirp period. Instead of relying solely on multiple sequential chirps in the time domain, the system exploits the frequency-time plane more efficiently by incorporating bidirectional ramps and stationary regions, creating additional independent signal samples that enable ambiguity resolution without extending the overall acquisition time.
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 reduces the overhead time in FMCW radar systems, enhancing the radar update rate and improving ambiguity resolution by efficiently processing data from both types of ramping regions, resulting in improved performance.
Implementation Method 1
receiving a reflected signal corresponding to the reflection of the frequency modulated continuous wave signal from one or more physical objects
Data Source
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AI summary
A method and apparatus for acquiring chirp data in a frequency modulated continuous wave (FMCW) radar system of a road vehicle. The method includes transmitting a FMCW signal comprising a plurality of ramping regions (12,14) in which a frequency of the FMCW signal ramps up to a first frequency or ramps down to a second frequency. The method also includes receiving a reflected signal (20) corresponding to the reflection of the FMCW signal from one or more physical objects. The reflected signal includes a plurality of ramping regions (12,14) corresponding to the ramping regions of the transmitted FMCW signal. The method further includes sampling the reflected signal by: taking a plurality of samples (26) in a ramping region in which the frequency of the reflected signal ramps up; and taking a plurality of samples (46) in a ramping region in which the frequency of the reflected signal ramps down.