Chirp Signal Phase Error Compensation in SAR Systems
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Solution Overview
Problem
Current synthetic aperture radar (SAR) systems face challenges in reducing satellite weight and improving signal characteristics due to distortion in direct digital synthesizer (DDS) type waveform generators, which affects the quality of chirp signals used for imaging.
Innovation Solution
An apparatus that pre-distorts the base band chirp signal by calculating and combining phase errors over time sections, using a phase distorter to adjust the signal phase based on average error values, thereby efficiently compensating phase errors and reducing complexity compared to full-time section compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a memory map type waveform generator is used to store chirp signal data in memory, then signal reliability is improved, but satellite weight increases due to large capacity memory requirements
Solution Approach 1:
The patent segments the time sections into multiple groups and processes them separately rather than storing all chirp signal data in memory. By dividing the time sections and processing each group independently with phase error compensation, the system eliminates the need for large capacity memory while maintaining signal reliability.
Solution Approach 2:
The patent applies preliminary phase error compensation to each time section group before processing. By pre-calculating and compensating phase errors for each segmented group, the system ensures signal reliability without needing to store all raw data in memory, thus reducing weight.
2Measurement precision
If phase error compensation is applied to all time sections, then signal quality is improved, but computational complexity increases
Solution Approach 1:
The patent divides all time sections into multiple groups and applies phase error compensation to each group separately. This segmentation reduces the computational burden on any single processing stage while maintaining overall signal quality through comprehensive coverage of all time sections.
Solution Approach 2:
The patent applies phase error compensation selectively to segmented groups of time sections rather than processing all time sections uniformly at once. This partial action approach reduces instantaneous computational complexity while achieving complete compensation across all time sections through the segmented processing strategy.
Data Source
AI summary
The present invention provides an apparatus for compensating a phase error of an RF band chirp signal by pre-distorting a base band chirp signal, including: a waveform generator to output the base band chirp signal; an RF modulator to output the RF band chirp signal by upconverting the base band chirp signal; an error calculation unit to calculate a phase error over time for a predetermined time by comparing the RF band chirp signal with an ideal chirp signal; a section division unit to divide the predetermined time into a plurality of time sections; a section combination unit to combine neighboring time sections based on the phase error; and a phase distortion unit to distort phase of the base band chirp signal in the combined time sections based on the phase error.