Radar Interference Suppression via Time-Frequency Spectrogram Thresholding
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Solution Overview
Problem
Radar communications face challenges in accurately processing received radar signal reflections due to interference from other radars, leading to undesirably low signal-to-noise ratio (SNR), especially when interfering radar systems' chirps are moderately to highly correlated in frequency and time.
Innovation Solution
Converting received radar reflections into a time-frequency domain and constructing a range response by identifying and removing interference using a suppression threshold, which involves producing a spectrogram through time-frequency analysis and setting interference signals to zero or attenuating them based on their magnitude within the threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If interference mitigation approaches are applied to radar signals, then interference suppression is improved, but signal-to-noise ratio deteriorates due to loss of samples
Solution Approach 1:
The patent transforms the radar signal processing from traditional time-domain or frequency-domain analysis to time-frequency domain analysis using spectrogram representation. This dimensional transformation allows simultaneous observation of both time and frequency characteristics, enabling precise identification and suppression of interference signals while preserving target signal components. The time-frequency domain provides an additional dimension for distinguishing between interference and target signals based on their spectral-temporal patterns.
Solution Approach 2:
The patent applies localized thresholding in the time-frequency domain where each time-frequency bin is independently evaluated against a suppression threshold. This local quality approach allows selective suppression of interference components in specific time-frequency regions while preserving target signal components in other regions. The suppression threshold is determined based on local signal characteristics, enabling adaptive interference mitigation that maintains signal-to-noise ratio in different parts of the spectrogram.
2Object-affected harmful factors
If traditional interference mitigation methods are used, then interference removal is achieved, but measurement precision deteriorates due to sample loss
Solution Approach 1:
By representing signals in the time-frequency domain through spectrogram analysis, the patent adds a frequency dimension to time-domain signal representation. This enables precise identification of interference signals based on their frequency characteristics over time, allowing accurate removal of interference while preserving target signal components. The time-frequency representation maintains complete signal information without sample loss, improving measurement precision for target characterization.
Solution Approach 2:
The patent replaces traditional mechanical or direct time-domain filtering methods with spectral analysis-based interference mitigation. Instead of using time-domain windowing or frequency-domain notch filtering that may cause sample loss or signal distortion, the patent uses spectrogram-based thresholding that operates on the energy distribution in the time-frequency domain. This substitution preserves signal integrity while achieving effective interference removal.
3Object-affected harmful factors
If aggressive interference suppression is applied, then interference signals are removed, but loss of information increases due to removal of useful signal components
Solution Approach 1:
The patent applies local quality by evaluating each time-frequency bin independently and applying suppression only where interference is detected. The suppression threshold is determined based on local signal characteristics in each time-frequency region, allowing selective removal of interference components while preserving target signal components. This localized approach prevents loss of useful signal information by maintaining different quality levels in different regions of the spectrogram based on actual signal content.
Solution Approach 2:
The patent employs feedback mechanisms where the suppression threshold is determined based on the observed signal characteristics in the time-frequency domain. The system continuously monitors the spectrogram, identifies interference patterns, and adjusts the suppression threshold accordingly. This feedback-based approach ensures that suppression actions are adaptive to the actual signal conditions, preventing loss of useful signal components while effectively removing interference.
Data Source
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AI summary
Aspects of the present disclosure are directed to implementations involving the transmission of radar signals and the processing of reflections of those signals as received from a target. As may be implemented with one or more embodiments, a spectrogram may be produced by converting reflections, of transmitted radar signals from a target, into a time-frequency domain using a time-frequency analysis. One or more suppression thresholds is determined for at least one frequency signal in the spectrogram, based on frequency characteristics of the converted reflections. A range response is constructed, characterizing the target and having interference signals removed in the time-frequency domain, by converting (into the range response) selected ones of the frequency signals in the spectrogram having a magnitude within the suppression threshold.