GNSS Time Receiver Multi-Constellation Synchronization
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Solution Overview
Problem
Satellite-synchronized network clocks rely on limited GNSS receivers, which can lead to unreliable timekeeping if a satellite signal becomes unreliable, and cannot determine which time source is less accurate or malfunctioning without additional sources for comparison.
Innovation Solution
Implementing a system that uses a single time receiver subsystem to sequentially receive and compare time signals from multiple GNSS constellations (e.g., GPS, Galileo, GLONASS, and BDS) to determine the reliability and accuracy of each source, allowing for enhanced security and resiliency without the need for additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single GNSS receiver is used to reduce hardware cost and complexity, then device cost and complexity are reduced, but timekeeping reliability deteriorates when satellite signals become unreliable
Solution Approach 1:
The single GNSS receiver is configured to perform multiple functions: it sequentially receives time signals from multiple different GNSS constellations (GPS, Galileo, GLONASS, BDS) and compares them to determine reliability. This multi-functionality allows the system to achieve the reliability benefits of multiple receivers while using only one physical receiver, thus reducing hardware complexity while maintaining timekeeping reliability.
Solution Approach 2:
The system implements periodic switching between different GNSS constellations, sequentially tuning the receiver to each constellation at predetermined intervals to receive time signals. This periodic action enables the single receiver to gather time data from multiple sources over time, allowing reliability assessment without requiring simultaneous multiple receivers.
2Reliability
If multiple GNSS receivers are used to compare time sources and detect malfunctions, then timekeeping reliability is improved, but hardware cost and complexity increase
Solution Approach 1:
Instead of using multiple dedicated receivers for different constellations, the system employs a single universal receiver that can be configured to receive signals from any GNSS constellation. The receiver is sequentially programmed to tune to different constellations at different time intervals, enabling one receiver to perform the work of multiple specialized receivers, thus reducing hardware complexity while maintaining verification capability.
Solution Approach 2:
The single GNSS receiver serves itself by sequentially monitoring multiple constellations and performing self-verification of time sources. The system uses its own receiver to collect time signals from multiple constellations, compare them, and determine reliability without requiring external verification hardware, thereby reducing overall system complexity.
3Device complexity
If time signals are received sequentially from multiple constellations using a single receiver, then hardware cost is reduced, but time synchronization frequency may be reduced
Solution Approach 1:
The system implements a periodic switching schedule where the single receiver sequentially tunes to different GNSS constellations at predetermined intervals. By optimizing the switching frequency and duration for each constellation, the system ensures that time signals are collected from multiple sources frequently enough to maintain accurate time synchronization, while preventing drift between switching events. This periodic multi constellation sampling maintains synchronization frequency despite using a single receiver.
Data Source
AI summary
A satellite-synchronized network clock may include an oscillator, a global navigation satellite system (GNSS) time receiver module, and a control subsystem. The GNSS time receiver module may include a time receiver, a multiplexer, and a plurality of source inputs. The control subsystem may configure the multiplexer and time receiver of the GNSS time receiver module to sequentially receive time signals from a plurality of GNSS satellite constellations. Methods of synchronizing multiple time sources may include sequentially receiving a first time signal from a first GNSS constellation, a second time signal from a second GNSS constellation, and a third time signal from a third GNSS constellation with a GNSS receiver. The methods may further include measuring a phase and frequency offset of each respective received time signal relative to an oscillator and comparing the measured offsets to determine the accuracy of each of the received time signals.