Local Oscillator Holdover Correction Using Temporary Reference Signals
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Solution Overview
Problem
Network nodes with local oscillators (LO) face performance impairment when the primary master timing reference source becomes unavailable, requiring costly and time-consuming human intervention for correction, especially in scenarios like GPS signal loss or network malfunctions.
Innovation Solution
A device with a local oscillator (LO) error corrector that disciplines the LO using a less accurate source when the primary reference is unavailable, determines offset errors upon the reference's temporary availability, and corrects these errors using information from that availability, ensuring continuous operation until the primary reference is restored.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single master timing reference source is used to discipline the LO, then the network node cost is reduced, but the network performance is impaired when the reference source becomes unavailable
Solution Approach 1:
The system dynamically changes the operating parameters of the LO by switching between different reference sources (GPS, network master timing, holdover mode) based on availability. When the primary reference becomes unavailable, the system transitions to using a less accurate alternative reference or holdover mode, accepting a parameter change in timing accuracy to maintain continuous operation.
Solution Approach 2:
The system prepares alternative reference sources and holdover capabilities in advance to cushion against the unavailability of the primary master timing reference. By having pre-configured fallback options (secondary references and holdover mode with mathematical models), the system ensures continuous operation without requiring human intervention when the primary reference fails.
2Measurement precision
If the LO is disciplined by an external timing reference source, then timing accuracy is improved, but human intervention is required when the reference becomes unavailable
Solution Approach 1:
The system performs self-service by automatically detecting when the primary master timing reference becomes unavailable and autonomously switching to alternative reference sources or holdover mode. The LO error corrector continuously monitors reference availability and performs automatic corrections using available references or mathematical models, eliminating the need for human intervention to maintain timing accuracy.
Solution Approach 2:
The system implements feedback mechanisms where the LO error corrector continuously monitors the availability and accuracy of reference sources. When the primary reference becomes unavailable, the feedback loop triggers automatic switching to alternative references or holdover mode, and continuously adjusts the LO based on offset error measurements from available references to maintain timing accuracy without human intervention.
3Duration of action of stationary object
If alternative less accurate references are used when the primary reference is unavailable, then continuous operation is maintained, but timing accuracy deteriorates
Solution Approach 1:
The system dynamically adjusts the timing discipline approach based on reference availability. When the primary accurate reference is unavailable, the system transitions to using less accurate alternative references or holdover mode with mathematical models. The LO error corrector continuously adapts by measuring offset errors against available references and applying corrections, maintaining dynamic operation continuity while managing timing accuracy degradation through active error compensation.
Data Source
AI summary
A device is provided having a local oscillator (LO) configured to generate a first signal comprising at least one of: timing information; frequency information; phase information; and combinations thereof. The device also has a LO error corrector comprising an input, the input configured to receive a second signal comprising at least one of: timing information; frequency information; phase information and combinations thereof, wherein the second signal is used for disciplining the LO. The LO error corrector is configured to: if the second signal is unavailable to discipline the LO, discipline the LO using a source that is less accurate than the second signal. Upon the second signal becoming at least temporarily available, the LO corrector determines an offset error of the LO relative to the second signal. If the second signal becomes unavailable before the device uses the second signal to discipline the LO on an ongoing basis, the LO corrector corrects the offset error of the LO relative to the second signal based information obtained during the second signal's temporary availability and disciplines the LO using a source that is less accurate than the second signal until the second signal becomes at least temporarily available at a subsequent time.