Distributed VNA Synchronization Without Shared LO or Reference Clock
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vector network analyzers (VNAs) face challenges in synchronizing test ports over long distances due to difficulties in establishing shared local oscillator (LO), reference clock, and trigger signals, particularly in antenna range measurements.
Innovation Solution
A distributed VNA system using digital signal processing to eliminate the need for shared LO, reference clock, and trigger signals by independently operating reference clocks and using a processing unit to compensate for reference errors through frequency adjustments and resampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If two one-port VNAs are used as a distributed VNA for long-distance measurements, then the measurement capability over long distance is improved, but the complexity of establishing shared LO, reference clock, and trigger connections worsens
Solution Approach 1:
The patent extracts the reference clock sharing requirement by allowing each VNA to operate with its own independent reference clock. The digital signal processing system compensates for the frequency difference between the two independent clocks, eliminating the need for complex physical connections to share a single reference clock while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces digital signal processing as an intermediary between the two VNAs. The DSP system receives signals from both VNAs, compensates for timing and frequency differences caused by independent reference clocks, and processes the combined data to produce accurate measurements, thereby simplifying the physical connection requirements.
2Measurement precision
If shared reference clock and LO signals are used to synchronize test ports, then the synchronization accuracy is improved, but the difficulty of establishing connections over long distance worsens
Solution Approach 1:
The patent enables each VNA to serve itself by using its own independent reference clock without requiring connection to a shared reference clock. The digital signal processing system automatically compensates for the frequency differences between the independent clocks, allowing the system to achieve synchronization accuracy without complex external connection infrastructure.
Solution Approach 2:
The patent changes the approach from fixed shared reference parameters to adjustable independent parameters. Each VNA operates with its own reference clock frequency, and the digital signal processing system dynamically adjusts for frequency differences through mathematical compensation, transforming a rigid connection requirement into a flexible parameter-based solution.
3Device complexity
If independent reference clocks are used in each VNA, then the connection complexity is reduced, but the reference error between clocks increases
Solution Approach 1:
The patent implements a feedback mechanism where the digital signal processing system continuously monitors the frequency difference between the two independent reference clocks and applies real-time compensation. The system measures the actual frequencies of both reference clocks, calculates the ratio between them, and uses this information to adjust the processing of signals from each VNA, thereby eliminating reference errors despite using independent clocks.
Solution Approach 2:
The patent combines signals from two VNAs with independent reference clocks through digital signal processing, creating a composite measurement system. The DSP system integrates the two independent signal sources, applying frequency compensation algorithms to merge them into a coherent measurement result, effectively combining the simplicity of independent clocks with the precision of synchronized measurements.
Data Source
AI summary
A method and system synchronize first and second VNAs for testing a DUT over a long distance. The method includes receiving at the second VNA an RF signal from the first VNA; mixing the RF signal and an LO signal at the second VNA to output an IF signal to an ADC; determining a reference error ratio between a first reference clock in the first VNA and a second reference clock in the second VNA; adjusting an LO frequency to a corrected LO frequency by applying the reference error to a desired LO frequency; mixing the RF signal and the adjusted LO signal to output the IF signal; and resampling the IF signal at an adjusted sample rate to output a corrected IF signal corrected for the reference error, without adjustments being made to the first or second reference clock.