Satellite Formation Synchronization for SAR Phase Error Reduction
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Solution Overview
Problem
Existing satellite-formation-based synthetic aperture radar systems face challenges in time, frequency, and space synchronization, leading to phase unwrapping errors and inaccurate terrain altitude measurements, which hinder high-precision, wide-range, three-dimensional imaging.
Innovation Solution
A satellite-formation-based remote sensing system comprising a master satellite and two concomitant satellites with synchronized spatial baselines, a time synchronization module, a frequency synchronization module, and a space synchronization module, ensuring that the satellites cover the same ground region simultaneously and compensate for phase errors caused by frequency drifts, allowing for precise terrain altitude measurement and spatiotemporal feature acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple single-view SAR remote sensing images are used to achieve large-area imaging, then the mapping width is improved, but the time synchronization problem arises causing discontinuous data in time and azimuth direction
Solution Approach 1:
The patent divides the imaging task among multiple satellites, where each satellite captures a specific portion of the ground area. The master satellite coordinates the formation and provides timing references, while concomitant satellites perform parallel imaging operations. This segmentation allows simultaneous coverage of large areas while maintaining temporal synchronization through the master satellite's coordination.
Solution Approach 2:
The master satellite serves as an intermediary that coordinates the timing and positioning of concomitant satellites. It provides reference signals and synchronization information to ensure that all satellites in the formation capture data at the same time, resolving the time synchronization problem while maintaining large-area coverage capability.
2Device complexity
If a single SAR satellite is used for imaging, then the device complexity is reduced, but the resolution and mapping width are limited
Solution Approach 1:
The patent merges multiple satellites into a coordinated formation where the master satellite and concomitant satellites work together to achieve enhanced imaging performance. By combining the data from multiple satellites with different spatial baselines, the system achieves both high resolution and wide mapping area, overcoming the limitations of a single satellite while managing complexity through standardized formation protocols.
3Measurement precision
If distributed synthetic aperture radar systems with long inter-satellite baseline are used, then the spatial resolution is improved, but the time, frequency, and space synchronization requirements increase leading to phase unwrapping errors
Solution Approach 1:
The master satellite continuously provides synchronization signals and timing information to concomitant satellites, creating a feedback loop that maintains temporal and spatial coherence across the formation. This feedback mechanism ensures that phase errors from the long inter-satellite baselines are continuously corrected, enabling high spatial resolution without unacceptable synchronization complexity.
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 enhances the precision of terrain altitude measurement and acquires accurate spatiotemporal features by ensuring temporal and spatial synchronization, reducing interferometric phase errors and enabling high-precision, wide-range, three-dimensional imaging.
Implementation Method 1
the synchronizing device forms the first spatial baseline A and the second spatial baseline B in time series based on synchronization in terms of time, frequency, and space
Implementation Method 2
Satellites equipped with synthetic aperture radars adopt the method of microwave active detection. Through the pulse compression in the range direction and the synthetic aperture technology in the azimuth direction
Implementation Method 3
Through the synthetic aperture interferometry technology, the phase information of the radar complex image data can be extracted to invert the information about small changes of terrain and surface
Implementation Method 4
a frequency synchronization module, ensuring that the satellites cover the same ground region simultaneously and compensate for phase errors caused by frequency drifts
Implementation Method 5
a measuring device configured to measure satellite attitude parameters of the master satellite, the first concomitant satellite, the second concomitant satellite, and the third concomitant satellite on a real-time basis, and to perform precise orbit determination
Data Source
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AI summary
The present invention relates a remote sensing system, or particularly a satellite-formation-based remote sensing system, wherein comprising: a master satellite provided with an SAR system as a payload thereof, a first concomitant satellite, and a second concomitant satellite, wherein the first concomitant satellite and the second concomitant satellite fly around the master satellite, and the master satellite is located on major axes of motion trajectories of the first concomitant satellite and the second concomitant satellite, so as to define a first spatial baseline and a second spatial baseline that have an identical cross-track baseline component. The present invention enables high-precision, wide-range, three-dimensional imaging based on the satellite-formation, while acquires spatiotemporal features of variation of a ground region according to the synchronization in terms of time, frequency, and space.