PLL-Synchronized RF Measurement Clocks Over EtherCAT Networks
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Solution Overview
Problem
Existing networked systems face challenges in synchronizing RF measurements across multiple RF measurement units due to impracticality of sharing a common sampling clock, often requiring distributed reference clocks that increase complexity, cost, and maintenance issues.
Innovation Solution
Implementing a controller-driven architecture with EtherCat networks and using phase lock loop circuits to synchronize RF measurements, utilizing a distributed clock signal to generate phase-locked sampling clocks through voltage-controlled oscillators and analog-to-digital converters, eliminating the need for additional clock distribution cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common sampling clock is shared across multiple RF measurement units, then synchronized sampling is achieved, but device complexity and cost increase due to impractical clock distribution
Solution Approach 1:
The system divides the clock distribution function into segments: a reference clock unit generates a master clock signal, while each RF measurement unit contains its own phase-locked loop (PLL) that independently generates local sampling clocks locked to the reference. This segmentation eliminates the need for complex physical clock distribution while maintaining synchronization through the PLL's phase-locking mechanism.
Solution Approach 2:
The phase-locked loop acts as an intermediary between the reference clock signal and the sampling clock requirement. The PLL receives the reference clock, processes it through phase detection and frequency synthesis, and outputs a sampling clock that is phase-coherent with the reference without requiring direct physical connection or complex distribution infrastructure.
2Reliability
If distributed reference clocks are used in RF measurement units, then synchronized sampling is achieved, but manufacturing cost and maintenance issues increase
Solution Approach 1:
The invention extracts the clock generation function from the reference clock unit and implements it locally in each RF measurement unit through PLL circuits. Instead of distributing complex clock signals throughout the system, each unit independently generates its own sampling clock by locking to the reference, simplifying assembly and reducing maintenance of clock distribution infrastructure.
Solution Approach 2:
Each RF measurement unit serves itself by generating its own sampling clock through the PLL circuitry. The unit autonomously locks its local clock to the reference clock signal, eliminating the need for external clock distribution infrastructure and reducing both manufacturing complexity and maintenance requirements.
3Reliability
If additional clock distribution cables are installed, then sampling clock synchronization is achieved, but space requirements and system complexity increase
Solution Approach 1:
The invention replaces the mechanical clock distribution system (cables, connectors, and physical clock trees) with an electronic substitution approach. The PLL circuits electronically generate synchronized clocks by locking to the reference signal, eliminating the need for extensive physical cable infrastructure while maintaining clock synchronization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves synchronized sampling across RF measurement units with reduced complexity, cost, and improved maintainability by using EtherCat networks and phase lock loop circuits, enhancing reliability and reducing space requirements.
Implementation Method 1
The phase lock loop circuit includes a first input to receive a distributed clock signal, includes a second input coupled to the first output of the voltage-controlled oscillator to receive the sampling clock, and includes an output coupled to the first input of the voltage-controlled oscillator to provide a phase locked signal to the voltage-controlled oscillator in response to the distributed clock signal and the sampling clock
Implementation Method 2
The voltage-controlled oscillator includes a first input and includes a first output couped to the first input of the analog-to-digital converter to provide a sampling clock to the analog-to-digital converter
Data Source
AI summary
A radio frequency measurement system comprises an analog-to-digital converter, a voltage-controlled oscillator, and a phase lock loop circuit. The analog-to-digital converter includes a first input to receive a radio frequency signal and includes a first output to provide a digital signal in response to the received radio frequency signal. The voltage-controlled oscillator includes a first input and includes a first output couped to the first input of the analog-to-digital converter to provide a sampling clock to the analog-to-digital converter. The phase lock loop circuit includes a first input to receive a distributed clock signal, includes a second input coupled to the first output of the voltage-controlled oscillator to receive the sampling clock, and includes an output coupled to the first input of the voltage-controlled oscillator to provide a phase locked signal to the voltage-controlled oscillator in response to the distributed clock signal and the sampling clock.