Geosynchronous Satellite Orbit Determination via Relay Doppler Augmentation
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Solution Overview
Problem
Current orbit determination techniques for geosynchronous satellites are inefficient due to the lack of appreciable Doppler shift in their radio frequency signals, requiring prolonged ranging signals to achieve orbital convergence, which hampers precise and rapid orbit estimation.
Innovation Solution
Deploying a relay satellite in a lower orbit with a high angular rate to augment the Doppler shift of RF signals from geosynchronous satellites, allowing the ground station to calculate the satellite's orbit using the combined Doppler shift and range information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ranging signals are used for orbit determination of geosynchronous satellites, then orbital information can be obtained, but the process requires prolonged observation time and many observations over extended periods
Solution Approach 1:
The patent introduces a relay satellite as an intermediary component between the ground station and the geosynchronous satellite. The relay satellite receives signals from the geosynchronous satellite and retransmits them to the ground station, enabling the ground station to observe signals that would otherwise be inaccessible directly. This intermediary approach allows orbit determination without requiring prolonged direct observation of the geosynchronous satellite.
2Loss of information
If transponded signals from geosynchronous satellites are used for orbit determination, then range information can be obtained, but little other orbital characteristic information is available due to minimal Doppler shift
Solution Approach 1:
The relay satellite acts as a mediator that enables the ground station to access Doppler shift information from the geosynchronous satellite. By receiving and retransmitting the signals, the relay satellite allows the ground station to measure the Doppler shift of the original geosynchronous satellite signals, providing access to orbital characteristic information that would be unavailable through direct transponded signal measurement alone.
3Measurement precision
If GPS signals are used for orbit determination, then accurate orbital parameters can be computed, but the system requires 4 or more simultaneous GPS satellite signals which may not always be available
Solution Approach 1:
The relay satellite provides an alternative signal path that does not depend on GPS satellite availability. By using the relay satellite as an intermediary to receive and retransmit signals from the geosynchronous satellite, the system can determine orbital parameters independently of GPS constellation availability, enhancing the versatility and reliability of the orbit determination system.
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 method accelerates the Doppler shift, enabling more rapid and precise orbit determination of geosynchronous satellites by combining the Doppler shift from the relay satellite and the geosynchronous satellite, thereby improving the efficiency of orbit determination processes.
Implementation Method 1
The signal received back at the ground will have appreciable Doppler shift compared to the original transmission. Multiple samples of the Doppler Shift can be used to estimate the orbit of the satellite.
Implementation Method 2
A relay satellite, which has a relatively high angular rate, can receive an RF signal from a geosynchronous satellite and transpond the RF signal to a ground station. The transponded RF signal can have an augmented Doppler shift with respect to the RF signal originally communicated from the geosynchronous satellite.
Data Source
AI summary
Technology for determining an orbit of a geosynchronous satellite is described. A ground station can receive a transponded (RF) signal from a relay satellite. The relay satellite can receive an RF signal from the geosynchronous satellite and transpond the RF signal to create the transponded RF signal. The ground station can identify a second Doppler shift associated with the transponded RF signal received at the ground station from the relay satellite. The RF signal received at the relay satellite from the geosynchronous satellite can be associated with a first Doppler shift. The ground station can determine a frequency of the transponded RF signal received at the ground station from the relay satellite. The first Doppler shift associated with the RF signal transmitted from the geosynchronous satellite to the relay satellite can be calculated using the frequency of the transponded RF signal and the second Doppler shift associated with the transponded signal. The orbit of the geosynchronous satellite can be determined based on the first Doppler shift associated with the RF signal.