Satellite Transfer Monitoring Using Array Antenna Phase Difference
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Solution Overview
Problem
The high cost and inefficiency of using TT&C stations for extended periods to monitor satellite transfers from initial to mission orbits, particularly with electric propulsion, which can lead to satellite loss if the satellite deviates from predicted trajectories.
Innovation Solution
A method and system utilizing a terrestrial array antenna with non-directional elementary antennas to estimate satellite direction through phase difference measurements, allowing simultaneous monitoring of multiple satellites within a wide field of view without moving the antenna, and using a reference calibration signal to compensate for phase instabilities in the reception chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TT&C stations are used to monitor satellite transfer for extended periods (3-6 months), then the satellite positioning can be ensured, but the monitoring costs become prohibitive
Solution Approach 1:
The patent replaces expensive, highly directional TT&C antennas with inexpensive, low-gain omnidirectional antennas. These cheap antennas accept signals from any direction without requiring precise tracking, making them suitable for long-duration monitoring where cost is critical. The system uses multiple such antennas in an array to achieve the necessary functionality through signal processing rather than through expensive hardware.
Solution Approach 2:
The patent replaces the mechanical tracking system (mobile TT&C stations that physically follow satellite movement) with an electronic signal processing system. Instead of mechanically moving antennas to track the satellite, the system uses phase difference measurements and signal correlation across a fixed array of omnidirectional antennas to determine satellite position and maintain monitoring throughout the transfer orbit.
2Measurement precision
If TT&C stations are used to monitor satellite transfer, then satellite position can be tracked, but the station network becomes overwhelmed by demand
Solution Approach 1:
The patent creates a universal monitoring system using omnidirectional antennas that can simultaneously track multiple satellites in transfer orbit without requiring dedicated TT&C stations for each satellite. The array antenna system processes signals from multiple satellites concurrently through signal correlation and phase difference analysis, providing a multi-functional solution that handles growing satellite deployment demands.
Solution Approach 2:
The patent uses signal copying and correlation techniques where the expected satellite signal is generated based on predicted orbit parameters, and this copied reference signal is correlated with actual received signals to detect and track satellites. This allows the system to identify satellites even with low-gain antennas by matching signal characteristics rather than requiring high signal strength from directional antennas.
3Ease of operation
If predicted trajectory is used to estimate satellite direction, then TT&C station antenna can be pointed in predicted direction, but satellite loss occurs if trajectory deviates
Solution Approach 1:
The patent implements continuous feedback monitoring where the array antenna system constantly measures phase differences and correlates received signals with predicted satellite positions. When actual satellite position deviates from predicted trajectory, the system detects this through signal correlation analysis and automatically updates the search pattern, providing real-time feedback that prevents satellite loss without requiring complex manual intervention.
Solution Approach 2:
The patent uses omnidirectional antennas that radiate in all directions rather than concentrating energy in a single direction. This excessive coverage area ensures that even if satellite position deviates from predictions, the satellite signal remains within the antenna's acceptance cone. The system accepts reduced signal strength per direction in exchange for comprehensive coverage that prevents satellite loss.
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 reduces monitoring costs, minimizes the risk of satellite loss, and allows for efficient detection and decoding of satellite signals over extended periods, even with less expensive antenna components.
Implementation Method 1
the position of said satellite being estimated as a function of at least one phase difference measurement, called 'useful phase difference', between signals corresponding to a target signal, transmitted by said satellite during the transfer phase, and received on a pair of elementary antennas of the array antenna
Implementation Method 2
the emission, by a reference calibration transmitter stationary with respect to the array antenna, of a reference calibration signal intended for the array antenna, the measurement of a phase difference, called 'phase difference calibration', between signals corresponding to the reference calibration signal received on the pair of elementary antennas, the compensation of the variations of the calibration phase difference measurements for the pair of elementary antennas on the useful phase difference measurements
Data Source
Figure 1~2c
Figure 3~6
AI summary
The present invention relates to a method (70) for monitoring a phase for transferring a satellite (20) from one earth orbit, called "initial orbit", to another earth orbit, called "mission orbit", in particular a transfer using electric propulsion means. The monitoring method comprises a step for estimating the direction of said satellite during said transfer phase by means of an earth array antenna (30) comprising a plurality of elementary antennas (31), each elementary antenna having a primary radiation lobe with a width greater than or equal to 20°, said elementary antennas (31) being oriented such that their respective fields of vision overlap, the direction of said satellite being estimated based on at least one useful phase difference measurement between signals corresponding to a target signal, transmitted by said satellite and received on a pair of elementary antennas (31).