Non-Invasive Reflection Coefficient Measurement via Time-Domain Signal Separation
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Solution Overview
Problem
Existing methods for measuring reflection coefficients in high-speed digital communication circuits are inadequate, as they either require invasive techniques like cutting signal lines or adding costly directional couplers, which are not suitable for real-time, full-duplex communication scenarios.
Innovation Solution
A method involving a measurement instrument that receives probed waveforms at two spaced locations on a signal line to calculate the reflection coefficient by delaying and subtracting waveforms, allowing for non-invasive, simultaneous measurement of incident and reflected signals without disrupting the communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directional couplers are embedded in the signal line to measure reflection coefficients, then measurement capability is improved, but device complexity, cost, and signal loss increase
Solution Approach 1:
The patent introduces an intermediary measurement instrument with time-domain analysis capability that mediates between the signal line and the measurement process. This instrument receives the composite signal and uses time-domain gating to separate incident and reflected signals based on their temporal separation, eliminating the need for directional couplers while maintaining measurement capability
Solution Approach 2:
The patent extracts the measurement function from the signal line itself by using an external time-domain reflectometer instrument. The instrument extracts incident and reflected signal components through time-domain processing, removing the need to embed measurement components within the signal line and thereby reducing device complexity
2Measurement precision
If network analyzer is used to measure reflection coefficient, then measurement capability is improved, but measurement speed is insufficient for high-speed digital signals
Solution Approach 1:
The patent replaces the frequency-domain measurement approach of network analyzers with a time-domain measurement approach using a time-domain reflectometer. This substitution enables direct measurement of high-speed digital signals by capturing waveforms in the time domain and processing them to extract reflection coefficients, achieving measurement speeds compatible with high-speed digital communication
Solution Approach 2:
The patent changes the measurement parameter domain from frequency domain (network analyzer) to time domain (TDR instrument). By measuring signals in the time domain and using time-domain gating to separate incident and reflected waves, the system achieves measurement capability for high-speed digital signals while maintaining reflection coefficient measurement precision
3Measurement precision
If signal line is cut and RF connector attached to measure reflection coefficient, then measurement capability is improved, but reliability and ease of operation deteriorate
Solution Approach 1:
The patent introduces a non-invasive measurement instrument that acts as an intermediary, coupling to the signal line without cutting or modifying it. The instrument receives the composite signal and processes it in the time domain to separate incident and reflected components, maintaining signal line integrity while enabling reflection coefficient measurement
Data Source
AI summary
A measurement instrument configured to perform an associated method separates two signals which are present on the same signal line at the same time (e.g., an incident signal and a reflected signal) so that it can measure each signal by itself. In an example, the method may include: receiving a first probed waveform from a first location on a signal line between a source device and a destination device while an output of the source device sends an incident signal to an input of the destination device via the signal line; receiving a second probed waveform from a second location on the signal line, while the output of the source device sends the incident signal to the input of the destination device via the signal line; and ascertaining from the first probed waveform and the second probed waveform the reflection coefficient at the input of the destination device.