Mobile Reference Clock Holdover Using ePRTC and GNSS Lock
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Solution Overview
Problem
Existing mobile reference clock systems using atomic clocks like rubidium or cesium clocks are limited in their usage time due to variations, with rubidium clocks varying 50 ns after 50 seconds and cesium clocks after half a day, making them unsuitable for practical applications requiring longer synchronization.
Innovation Solution
The mobile reference clock system incorporates an enhanced primary reference time clock (ePRTC) with a GNSS receiver and a power supply, allowing operation in both GNSS-locked and holdover modes, providing higher frequency accuracy and enabling usage up to 40 days without GNSS signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If atomic clocks (rubidium or cesium) are used in mobile reference clock systems, then frequency accuracy is provided, but usage time is limited due to variations (rubidium varies 50 ns after 50 s, cesium varies 50 ns after 13.8 h)
Solution Approach 1:
The patent combines multiple primary reference clocks (PRCs) with different atomic clock types (rubidium and/or cesium) into a single mobile reference clock system. By merging these clocks and using their combined output signals, the system achieves both high frequency accuracy and extended usage time, overcoming the limitation of individual atomic clocks that drift after short periods.
2Adaptability or versatility
If a mobile reference clock system is transferred and separated from the master clock, then mobility and independent operation are achieved, but synchronization accuracy decreases due to variations during transfer
Solution Approach 1:
The system merges multiple PRCs with different drift characteristics to create a composite time reference that maintains high synchronization accuracy even when separated from the master clock. The combination of rubidium and cesium clock signals compensates for individual clock variations during mobile operation.
Solution Approach 2:
The patent changes the temporal parameter of the system by using clocks with different stability characteristics over time. The rubidium clock provides short-term stability while the cesium clock provides long-term stability, and their combined output maintains accurate synchronization across the entire operational period despite mobile transfer.
Data Source
Figure 1
AI summary
A mobile reference clock system comprising a primary reference clock, a use of an enhanced primary reference time clock, ePRTC, and a method for synchronizing a clock.