Electronic Scanning Radar Interference Suppression via Phase Correction
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Solution Overview
Problem
Electronic scanning radar systems with time division reception face challenges in accurately detecting and suppressing interference signals, particularly in FM-CW and CW systems, due to phase errors and aliasing issues, which affect the determination of interference azimuth and measurement accuracy.
Innovation Solution
The system employs a structure with a transmission antenna, reception antenna, mixer, switcher, A/D converter, and processing components for short-time data cutting, frequency spectrum computation, phase correction, and Digital Beamforming to detect and suppress interference signals by analyzing beat frequencies and phase corrections, allowing for directivity-based interference suppression even in time division reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If time division reception is used to reduce device complexity, then the number of A/D converters is reduced, but phase errors occur due to switching delay time
Solution Approach 1:
The patent changes the parameter of sampling timing to coincide with the peak of the switching waveform. By adjusting the sampling phase parameter to match the peak timing, the system eliminates phase errors caused by switching delay while maintaining time division reception architecture, thus resolving the contradiction between device complexity reduction and measurement precision maintenance
2Device complexity
If switching is performed in time division reception, then device complexity is reduced, but interference signal azimuth detection becomes inaccurate due to aliasing
Solution Approach 1:
The patent applies preliminary action by pre-processing the switching waveform to identify its peak timing before sampling occurs. The sampling clock is then synchronized to this pre-determined peak timing, ensuring that interference signals are sampled at the optimal phase point. This preliminary synchronization action prevents aliasing errors in interference azimuth detection while maintaining the simplified time division reception structure
3Device complexity
If sampling is performed at fixed intervals, then device complexity is reduced, but measurement accuracy deteriorates due to phase errors from switching delay
Solution Approach 1:
The patent implements feedback by using the detected peak timing of the switching waveform to dynamically adjust the sampling clock phase. The system continuously monitors the switching waveform, detects its peak, and feeds this timing information back to synchronize the sampling operation. This feedback mechanism eliminates phase errors from switching delay while maintaining simple fixed-interval sampling control
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 effectively detects and suppresses interference signals, ensuring accurate detection of target distance and speed by correcting phase errors and aliasing issues, thereby enhancing measurement accuracy and interference suppression in electronic scanning radar systems.
Implementation Method 1
the received signal S2 and the transmitted signal S1 are mixed with each other as shown in FIG. 1(b), thereby generating a beat signal S3 which component is a frequency difference between the received signal and the transmitted signal (beat frequency fb)
Implementation Method 2
a time difference occurs which is determined by the azimuth of the target with respect to each antenna, a position where each antenna is arranged and the frequency of the received signal between channels of the received data
Implementation Method 3
the structure as shown in FIG. 5 having a switcher 7 arranged between each antenna element 6 and an AD converter 13 in order to receive in divided time
Data Source
AI summary
A sampled beat signal is cut out into two or more short time data in a time direction concerning each antenna component. From a frequency spectrum of the short time data, an interference element frequency of an interference wave is detected. From the interference element frequency of the interference wave, two or more candidates of the frequency before aliasing of the interference wave are produced, and phase correction is executed on each candidate. Digital Beamforming is executed on the corrected frequency so as to extract maximum peaks of the power of an azimuth direction, and the frequency candidate showing the maximum peak power is selected and the arrival azimuth of the interference element is estimated. A filter for suppressing the interference element is applied on the short time data from the estimated arrival azimuth of the interference element so as to suppress the interference element.