Clock Source Switching With OCXO Compensation for Low Sync Jitter
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Solution Overview
Problem
Existing 5G RU equipment struggles to smoothly switch between GPS and PTP clock input sources when GPS satellite reception is interrupted or degraded, leading to significant time synchronization jitter.
Innovation Solution
A device comprising a multiple input source stability detection module, an input source adaptive stability detection module, an input source switching module, and an OCXO dynamic compensation module, which detects and dynamically adjusts clock input sources to maintain time synchronization by switching to stable sources and compensating OCXO input signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automatic switching between GPS and PTP input sources is implemented, then reliability of time synchronization is improved, but time synchronization jitter increases during switching process
Solution Approach 1:
The patent pre-warms up the backup clock source (PTP) before switching is needed by continuously monitoring its stability and maintaining it in a ready state. This preliminary action ensures that when GPS fails, the PTP source is already stabilized and can take over immediately without causing synchronization jitter, thus resolving the contradiction between reliability and precision during switching.
Solution Approach 2:
The patent implements a buffer mechanism by continuously monitoring the stability of both GPS and PTP sources and maintaining a ready-state backup. This cushioning approach prevents abrupt transitions that would cause jitter, allowing smooth switching that maintains both reliability and time synchronization precision.
2Adaptability or versatility
If multiple clock input sources are supported, then adaptability of the system is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic selection and monitoring of multiple clock sources (GPS, PTP, OCXO) with automatic switching capabilities. The system dynamically adjusts which source is active based on real-time stability monitoring, providing adaptability to different deployment scenarios while managing complexity through automated control algorithms that simplify the switching logic.
Solution Approach 2:
The system performs self-monitoring and self-switching between clock sources without external intervention. The automatic detection of GPS failure and autonomous switching to PTP or OCXO sources reduces the need for complex external control mechanisms, thereby managing system complexity while maintaining high adaptability to various operating conditions.
Data Source
AI summary
A method for smoothly switching clock input sources is disclosed. A precision time protocol (PTP) input source is selected according to an initial configuration for time synchronization. It is determined whether pulse signals of the PTP input source within a time duration T are detected as a normal state. If the pulse signals of the PTP input source within the time duration T are detected as the normal state, the PTP input source is locked. An oven-controlled crystal oscillator (OCXO) input source is adjusted, according to a PTP timestamp for calibration, to enable the pulse signals of the OCXO input source to follow the pulse signals of the PTP input source.