Picosecond Clock Synchronization via Phase Estimation on Copper Links
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Solution Overview
Problem
Conventional methods for synchronizing clocks in federated architectures, such as those used in RF ranging/timing systems and signal intelligence applications, face challenges with achieving precise timing synchronization and frequency syntonization due to limitations in traditional copper cabling and the need for high-frequency references, which are costly and complex to implement.
Innovation Solution
A system utilizing a precision time/frequency estimator (PTFE) that determines and corrects frequency and phase differences between reference and measured sensors, allowing for simultaneous synchronization and syntonization of clocks to within 10 ps without requiring terahertz clocks or fiber-optic cabling, using lower-stability clocks and lower-bandwidth signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Time Interval Counters (TIC) are used to measure time difference between pulses from independent sources, then timing synchronization can be achieved, but the system requires terahertz (THz) level clock signals which are not supported by traditional copper cabling and would require costly upgrade to fiber optic cabling
Solution Approach 1:
The patent replaces the mechanical/electrical THz clock signal transmission system with a optical-based phase measurement system. Instead of using TIC with THz clock signals that require fiber optic cabling, the invention uses a phase detector to measure phase differences of optical clock signals, enabling precise timing synchronization while maintaining compatibility with traditional copper cabling infrastructure.
2Measurement precision
If sharp pulse edges are used to preserve high frequencies for accurate timing measurement, then timing precision is improved, but the system requires broadband cabling and high-frequency references that increase system complexity and cost
Solution Approach 1:
The patent substitutes the electrical sharp pulse edge detection system with an optical phase detection system. Instead of relying on sharp pulse edges that require broadband cabling, the invention uses continuous optical clock signals whose phase differences are measured by a phase detector, achieving equivalent or superior timing precision without the need for broadband electrical cabling or high-frequency electrical references.
3Measurement precision
If low pulse transmission rate is used to prevent ambiguity in pulse identification, then pulse identification accuracy is improved, but excessive time is required to average out sampling errors, reducing productivity
Solution Approach 1:
The patent transitions from discrete pulse-based measurement to continuous phase measurement. Instead of relying on periodic pulses that require low transmission rates to avoid ambiguity, the system continuously measures the phase difference between optical clock signals, eliminating pulse identification ambiguity while enabling rapid synchronization without excessive averaging times.
Solution Approach 2:
The patent uses the periodic nature of optical clock signals in a continuous phase measurement approach. By measuring phase differences at each cycle of the optical clock signals rather than relying on infrequent discrete pulses, the system achieves both unambiguous identification and rapid averaging of sampling errors through continuous measurement.
4Measurement precision
If high sampling frequency is used to achieve precise relative timing with integer resolution, then timing precision is improved, but the system requires high-frequency references that increase system complexity and cost
Solution Approach 1:
The patent replaces the electrical high-frequency reference system with an optical clock signal system. By using optical frequencies (which are inherently much higher than electrical frequencies) for the clock signals being measured, the system achieves fine timing resolution through phase measurement without requiring additional high-frequency electrical references or interpolation techniques.
Data Source
AI summary
Systems and related methods for simultaneous high precision synchronization and syntonization of multiple sensors or clocks utilize a precision estimator that receives clock signals and time mark signals from both sensors (a reference sensor and a clock to be measured against the reference sensor). A precision time and frequency estimator determines a time offset, frequency offset, and phase offset of the measured sensor relative to the reference sensor. Associated systems can additionally determine the propagation delay between two remote subsystems connected by a communications channel. The communications channel may be a bidirectional duplexed or multiplexed channel allowing for mutual exchange of timing information along a single non-dedicated cable between sensors. Sensors may be synchronized to within 10 ps of each other without the need for THz clocks or fiber-optic cabling.