Bistatic SAR Phase Synchronization Using Time Slot Embedding
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Solution Overview
Problem
Conventional Bi-satellite formation SAR systems face interruptions and reduced efficiency due to phase synchronization challenges, particularly with azimuth phase errors and low-frequency phase noise, which affect imaging focusing and interferometric phase accuracy.
Innovation Solution
A phase synchronization method and equipment that utilize time slots between radar signal transmissions to send phase synchronization signals, determining pulse widths and starting times to ensure continuous operation, using linear frequency modulation signals with the same carrier frequency as the radar signals to simplify system design and improve compensation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated phase synchronization signal with different carrier frequency is transmitted after stopping radar signal, then phase synchronization can be achieved, but radar working efficiency is reduced and system design complexity increases
Solution Approach 1:
The patent implements continuous radar signal transmission without interruption by embedding phase synchronization signals within the radar signal transmission process. The synchronization signals are transmitted during designated time slots within the radar pulse sequence, allowing both radar operation and phase synchronization to occur simultaneously without stopping the radar, thus maintaining continuous useful action and high working efficiency
Solution Approach 2:
The patent makes the radar signal serve dual purposes: both radar detection and phase synchronization. By using the same carrier frequency for both radar signals and phase synchronization signals, and by embedding synchronization information within the radar signal structure, the system achieves multi-functionality where one signal transmission accomplishes both radar imaging and phase synchronization tasks, eliminating the need for separate dedicated synchronization signals
2Reliability
If a dedicated phase synchronization signal with different carrier frequency is transmitted, then phase synchronization can be achieved, but system design complexity increases
Solution Approach 1:
The patent uses the same carrier frequency for both radar signals and phase synchronization signals. This homogeneity in frequency simplifies the system design by eliminating the need for separate frequency synthesis and conversion circuits. The synchronization signals are generated and transmitted using the same signal chain as the radar signals, reducing hardware complexity and design difficulty
3Reliability
If phase synchronization signal with different carrier frequency is used, then synchronization can be achieved, but compensation accuracy is reduced due to frequency conversion requirements
Solution Approach 1:
The patent changes the key parameter of carrier frequency to be identical for both radar and phase synchronization signals. This parameter change eliminates the need for frequency conversion and proportional scaling operations. The phase compensation can be directly applied to the radar signals using the synchronization data without additional frequency transformation steps, thereby maintaining high compensation accuracy
Data Source
AI summary
A phase synchronization method includes: pulse widths of first and second phase synchronization signals and starting time of transmission of first and second phase synchronization signals are determined, wherein starting time is located between two successive moments when radar signals are transmitted; first spaceborne SAR is controlled to transmit first phase synchronization signal to second spaceborne SAR according to pulse width and starting time of first phase synchronization signal; second spaceborne SAR is controlled, according to pulse width and starting time of second phase synchronization signal, to transmit second phase synchronization signal to first spaceborne SAR; compensation phase is determined according to peak phases of first and second phase synchronization signals received by second and first spaceborne SARs respectively; and phase synchronization compensation is performed, according to compensation phase, on radar signals received by first spaceborne SAR and second spaceborne SAR.