FM-CW Radar Interference Suppression via Segmented Signal Processing
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Solution Overview
Problem
Electronically scanned radar systems using the FM-CW technique face difficulties in suppressing interference signals from other vehicles, as the frequency modulation of interference waves differs from that of reflected signals, leading to broadband interference that complicates directional distinction and accurate measurement.
Innovation Solution
An electronically scanned radar system with a data cutting out part, frequency spectrum calculation, interference frequency detection, and removal parts, utilizing a projection matrix and digital beam forming to identify and remove interference components, allowing for accurate detection of target distance and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FM-CW technique is used for distance and speed measurement, then measurement capability is improved, but interference from other vehicles cannot be suppressed
Solution Approach 1:
The patent segments the received signal into multiple short-time data portions (N-M+1 data portions) by cutting out continuous data segments. This segmentation allows the system to process different time portions separately, enabling identification and suppression of interference signals that vary in frequency over time, while preserving the FM-CW measurement capability for distance and speed.
Solution Approach 2:
The patent dynamically adapts the signal processing by detecting frequency variations in different time portions. The interference frequency detection part analyzes frequency changes across time, and the interference component removal part dynamically adjusts processing based on detected interference characteristics. This dynamic approach allows suppression of time-varying interference while maintaining measurement precision.
2Object-affected harmful factors
If interference suppression filter is applied, then interference components are suppressed, but directional distinction is lost
Solution Approach 1:
The patent segments the signal processing into distinct functional parts: interference frequency detection part, peak direction extraction part, and interference component removal part. The directionality information is extracted from the frequency spectrum of short-time data before interference removal, allowing the system to suppress interference while preserving azimuth detection capability through the projection matrix that maintains spatial information.
Solution Approach 2:
The patent introduces an intermediary processing stage where frequency spectrum calculation is performed on short-time data before interference removal. This intermediary step allows the system to identify interference characteristics and directions without immediately removing signals, enabling directional distinction to be maintained while interference suppression is applied through the projection matrix.
3Measurement precision
If broadband interference is present, then measurement accuracy deteriorates, but frequency modulation distinction is lost
Solution Approach 1:
The patent segments the continuous received signal into multiple short-time data portions (N-M+1 portions) by cutting out continuous data segments of length M. This segmentation transforms the broadband interference problem into manageable frequency analysis of individual time portions, where interference frequency can be detected and suppressed while maintaining measurement accuracy through the projection matrix 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
The system effectively suppresses interference signals by identifying and removing frequency components that vary with time, maintaining measurement accuracy and directional distinction, even in environments with multiple radar systems.
Implementation Method 1
the reflected signal, or the reception signal Rx1, is mixed with the transmission signal Tx. This mixing produces a beat signal S, shown by (b) of FIG. 1, having a component of a frequency difference (beat frequency fb) between the transmission and reception signals.
Implementation Method 2
an AD converter for obtaining reception data consisting of an N number of sampled data by sampling the beat signal obtained by the mixer at a predetermined sampling frequency
Implementation Method 3
The transmission wave Tx transmitted in a fan-like form is reflected by a target (e.g., oncoming vehicle 52), for the reception of a reflected signal Rx1 to thereby perform scanning of the fan-like region.
Implementation Method 4
In the DBF, an azimuth is detected by digitizing a received data using an AD converter, and then correlating each channel with a vector data (mode vector)
Data Source
AI summary
A sampled beat signal RD is split into a plurality of short-time data SD in the time direction, for each of antenna elements. Interference component frequency of an interference wave is detected from a frequency spectrum of the short-time data SD. A digital beam forming process is performed for the interference component frequency of the interference wave to extract a peak of the electrical power of an azimuth direction and estimate an absolute value of an incoming direction of interference components. Based on the absolute value of the incoming direction of the estimated interference components, a filter for suppressing the interference components is operated to suppress the interference components.