FMCW Radar Sensor Synchronization via Complex Window Functions
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Solution Overview
Problem
Synchronizing multiple high-frequency components in FMCW radar sensors is challenging due to signal propagation time differences, especially in spatially separated modules, making precise synchronization difficult and costly, particularly in highly autonomous driving applications where existing components are used in parallel.
Innovation Solution
Employing a complex-valued window function to compensate for synchronization signal propagation time differences by shifting the spectrum of the intermediate-frequency signal, effectively simulating a change in object distance without adjusting synchronization signal run lengths, allowing for simpler and more efficient synchronization of high-frequency components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple high-frequency modules are spatially separated to meet performance requirements, then the radar sensor can process more targets and improve measurement precision, but synchronization errors occur due to signal propagation time differences
Solution Approach 1:
The patent applies parameter changes by modifying the window function from a real-valued to a complex-valued function. The complex window function introduces a phase parameter that can be adjusted to compensate for synchronization errors. By changing the mathematical parameters of the window function, the system can correct timing offsets without physically adjusting the hardware synchronization, thus resolving the contradiction between spatial separation and synchronization accuracy.
2Reliability
If synchronization signal propagation time is compensated by adjusting signal run lengths, then synchronization accuracy improves, but device complexity and board space requirements increase
Solution Approach 1:
The patent replaces the mechanical/physical approach of adjusting signal run lengths with an electronic/software-based approach using complex window functions. Instead of physically modifying the synchronization signal paths or adding complex delay circuits, the invention uses mathematical processing in the frequency domain to achieve the same synchronization effect, thereby reducing device complexity and board space requirements.
3Reliability
If symmetric arrangement or detours are used to avoid propagation delay differences, then synchronization accuracy improves, but board space and design effort increase
Solution Approach 1:
The patent changes the parameters of the window function to compensate for asymmetric signal propagation paths. Instead of requiring symmetric physical arrangements, the complex window function's phase parameter can be tuned to account for any physical layout, allowing flexible PCB design without increasing board space while maintaining synchronization accuracy.
4Ease of manufacture
If existing mass-produced components are used in parallel to meet performance demands, then cost is reduced, but synchronization between components becomes more difficult
Solution Approach 1:
The patent replaces complex hardware synchronization mechanisms with a software-based complex window function approach. This allows the use of standard, mass-produced high-frequency modules without requiring custom synchronization hardware, thereby maintaining low manufacturing costs while achieving accurate synchronization through mathematical processing.
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 accurate synchronization of high-frequency components, reducing synchronization errors and improving the performance of radar sensors by aligning the spectra from multiple modules, enhancing the signal-to-noise ratio and reducing the need for complex synchronization adjustments.
Implementation Method 1
each having a transmitter section for sending a frequency-modulated transmit signal and/or a receiver section for receiving a radar echo, and at least two of the high-frequency modules each have a receiver section and each receiver section is assigned a mixer which generates an intermediate frequency signal by mixing the received signal with a portion of the transmitted signal
Implementation Method 2
the evaluation unit, and the evaluation unit is configured to record the intermediate frequency signal over a measurement period as a function of time and to subject the time signal thus obtained to a Fourier transform
Implementation Method 3
However, due to the Doppler effect, the frequency of the peak also depends on the object's relative velocity
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an FMCW radar sensor comprising a plurality of high-frequency modules (10, 12), which are synchronized with one another by a synchronization signal (sync) and of which at least one has a transmitting part (16) for generating a modulated-frequency transformation signal (TX), and of which at least two high high-frequency modules (10, 12) that are separated physically from one another each have a receiving part (20) for receiving a radar echo (E), each receiving part (20) being assigned a mixer (22), which generates an intermediate-frequency signal (Z1, Z2) by mixing the received signal (RX) with a proportion of the transmitted signal (TX), and an evaluation unit (24, 34), and the evaluation unit (24, 34) being designed to record the intermediate-frequency signal (Z1, Z2) over a measurement period as a function of time and to subject the time signal (S1, S2) that is obtained to a Fourier transformation, characterized in that at least one (34) of the evaluation units is designed to window the time signal (S1) with a complex-value window function (V) before the Fourier transformation in order to compare a propagation time difference of the synchronization signal (sync) between the receiving parts (20).