Satellite Orbit Determination Using Two-Way Ground Station Timing
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Solution Overview
Problem
Conventional orbit determination and time synchronization techniques for satellites rely heavily on GNSS services like GPS or Galileo, which can be undesirable due to dependency on external systems, and there is a need for more robust methods that do not depend on such services.
Innovation Solution
A satellite-based method using two-way user measurements with ground stations to exchange time-stamped messages, allowing autonomous orbit and clock parameter determination onboard the satellite without relying on GNSS, utilizing collaborative ground stations for robust and resilient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ODTS techniques based on GNSS services are used, then orbit determination and time synchronization can be achieved, but dependency on external systems increases
Solution Approach 1:
The satellite performs autonomous orbit determination and time synchronization using its own onboard computer and sensors, combined with measurements from ground stations. The satellite independently processes the data exchanged with ground stations to determine its own orbit parameters and synchronize its clock, without relying on external GNSS services or complex ground-based ODTS infrastructure.
Solution Approach 2:
Ground stations serve as intermediaries that exchange time-stamped measurement data with the satellite. These ground stations capture and transmit timing information that the satellite uses for autonomous ODTS computation, simplifying the ground segment while maintaining reliability.
2Reliability
If GNSS-based ODTS techniques are used, then orbit and time can be determined, but robustness against external system failures decreases
Solution Approach 1:
The ODTS function is segmented between the satellite's onboard computer and simple ground stations. The satellite performs the complex computation autonomously using data from multiple ground stations, while the ground stations only need to perform simple time-stamped measurements and data exchange. This segmentation makes the system more robust as each component has a simplified, well-defined function.
3Extent of automation
If autonomous onboard ODTS computation is implemented, then dependency on external services is reduced, but computational requirements onboard increase
Solution Approach 1:
The satellite performs autonomous ODTS computation using a subset of available data from ground stations. The system processes timing information from multiple ground stations to determine orbit parameters and synchronize time, performing just enough computation onboard to achieve autonomy without requiring excessive processing power or energy consumption.
Data Source
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AI summary
This application relates to a method, comprising, at a satellite, in each of a plurality of time periods, communicating with a respective pair of ground stations comprising a first ground station and a second ground station, to exchange a first downlink message and a first uplink message with the first ground station and to exchange a second downlink message and a second uplink message with the second ground station, wherein the first and second downlink messages and the first and second uplink messages are time-stamped messages, and determining one or more orbit parameters indicative of an orbit of the satellite based on known positions of respective first and second ground stations relating to one or more of the plurality of time periods and based on first timing information relating to times of reception and transmission of respective first uplink and downlink messages and second timing information relating to times of reception and transmission of respective second uplink and downlink messages in the one or more of the plurality of time periods. The application further relates to a corresponding satellite.