FMCW Radar Frequency Hopping for Low-Interference Speed Measurement
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Solution Overview
Problem
Existing in-vehicle radar systems experience significant interference issues, leading to reduced detection probability and increased ghost probabilities, which are not effectively addressed by current anti-interference methods like intra-frame random frequency hopping, which complicates speed calculation using FFT processing.
Innovation Solution
A method for controlling radar frequency hopping is introduced, where start frequencies of FMCWs are determined based on a monotone function, allowing for sequential transmission and reducing interference probability, enabling the use of simple digital signal processing like FFT for speed measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If intra-frame random frequency hopping technology is used to reduce mutual interference probability, then interference between radars is reduced, but existing simple digital signal processing methods like FFT cannot be used to calculate relative speed, leading to increased processor calculation amount
Solution Approach 1:
The patent changes the frequency hopping pattern from random to deterministic by defining start frequencies of FMCWs based on a specific function (Formula 1: fk = f0 + kΔf, where f0 is the center frequency, k is the FMCW index, and Δf is the frequency interval). This parameterized approach maintains interference reduction while enabling compatibility with FFT-based speed measurement, thus reducing processor calculation complexity.
Solution Approach 2:
The patent introduces dynamic frequency adjustment within each detection subframe by sequentially changing the start frequency of each FMCW according to the deterministic function. This dynamic frequency hopping allows the radar to adapt to interference conditions while maintaining a structured pattern that preserves FFT applicability for speed measurement.
2Measurement precision
If frequency hopping is performed to reduce mutual interference, then detection accuracy is improved, but the calculation complexity for speed measurement increases without optimized frequency selection
Solution Approach 1:
The patent optimizes the frequency interval parameter Δf in the deterministic frequency hopping function to balance interference reduction and FFT compatibility. By carefully selecting Δf, the system achieves both improved detection accuracy through frequency diversity and maintained compatibility with efficient FFT-based speed calculation methods.
Solution Approach 2:
The patent implements periodic frequency hopping within detection subframes, where the frequency pattern repeats in a structured manner. This periodicity, combined with the deterministic frequency sequence, allows the use of FFT for efficient speed measurement while still achieving interference reduction through frequency diversity.
3Reliability
If the quantity of FMCWs in a detection subframe is increased to improve interference resistance, then anti-interference capability is enhanced, but processing time and calculation load increase
Solution Approach 1:
The patent divides the detection process into multiple detection subframes, each containing a optimized number of FMCWs. This segmentation allows the system to achieve sufficient interference resistance through frequency hopping within each subframe while keeping the processing time for each subframe manageable, thus balancing reliability and processing efficiency.
Solution Approach 2:
The patent applies frequency hopping to only the necessary extent within each detection subframe rather than across the entire detection frame. By limiting the number of FMCWs per subframe and using deterministic frequency selection, the system achieves adequate anti-interference capability without excessive processing time or calculation load.
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 mutual interference and simplifies speed calculation by ensuring frequency hopping occurs within a specific bandwidth range, allowing for efficient speed measurement using existing processing methods.
Implementation Method 1
The oscillator generates a signal whose frequency increases linearly with time (frequency-modulated continuous wave (FMCW))
Implementation Method 2
The mixer performs frequency mixing on the millimeter wave signal and the local oscillator signal to obtain an IF signal
Implementation Method 3
controlling a radar to sequentially transmit a plurality of FMCWs by performing frequency hopping based on the determined start frequencies
Data Source
AI summary
A method for controlling radar frequency hopping includes determining start frequencies of a plurality of frequency modulated continuous wave (FMCWs) based on a first function, and controlling a radar to sequentially transmit the plurality of FMCWs by performing frequency hopping based on the determined start frequencies.