Propagation Delay Measurement Using Simultaneous TDR Excitation

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Solution Overview

Problem

Existing methods for determining propagation delay in transmission lines require complex circuitry and are inefficient when dealing with transmission lines of equal delay, as they necessitate separate measurements for each line.

Innovation Solution

The technique involves simultaneously exciting both transmission lines and using the difference in time between the excitation and reflection to determine the propagation delay, reducing the complexity of circuitry by utilizing a programmable FPGA to detect signal edges and generate clock pulses based on thresholds, allowing for the calculation of propagation delay through the difference in periods measured.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If separate measurements are performed for each transmission line, then measurement accuracy is maintained, but device complexity and measurement time increase

Engineering Contradiction:

Improvepropagation delay measurement accuracyVSAvoidcircuitry complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the measurement of two transmission lines into a single simultaneous operation. By exciting both transmission lines at the same time and using a single TDR circuit, the system measures propagation delays of both lines without requiring separate measurement setups, thereby reducing device complexity while maintaining measurement accuracy

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The TDR circuit is designed to perform multiple functions by measuring both transmission lines simultaneously. The same circuit infrastructure is used to excite and measure both lines, making the measurement system universal rather than requiring dedicated circuits for each line

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If separate measurements are performed for each transmission line, then measurement accuracy is maintained, but measurement time increases

Engineering Contradiction:

Improvepropagation delay measurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The measurement process continues simultaneously for both transmission lines without interruption. The TDR circuit continuously monitors both lines during the same time interval, eliminating the need to wait for one measurement to complete before starting the next, thus reducing total measurement time

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If simultaneous excitation of both transmission lines is performed, then productivity is improved, but difficulty of detecting and measuring increases

Engineering Contradiction:

Improvemeasurement efficiencyVSAvoidsignal detection complexity

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the measurement process by using separate detection paths for incident edges and reflected edges. By dividing the signal detection into distinct components (incident signal detection and reflected signal detection), the system manages the complexity of simultaneous measurements while maintaining productivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses an intermediary approach by measuring reflected edges from one transmission line to determine propagation delay. The reflection serves as an intermediary signal that provides measurement information without requiring direct simultaneous measurement of both lines, thus managing detection complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This method simplifies the determination of propagation delay by reducing the amount of circuitry required and enabling simultaneous measurement across transmission lines of equal delay, improving efficiency and accuracy.

Implementation Method 1

Propagation delay in a transmission line corresponds to the time delay it takes for a signal to propagate from one end of the transmission line to another end of the transmission line

Methodology Applied

Scientific EffectSignal propagation: Conduction (electrical)

Implementation Method 2

detecting a reflected edge of the second signal on the second transmission line

Methodology Applied

Scientific EffectSignal reflection: Reflection

Data Source

PatentUS8988081B2Determining propagation delay

Publication Date: 2015.03.24 TERADYNE INC

AI summary

Techniques for obtaining a propagation delay through first and second transmission lines having substantially equal propagation delays may include: providing a first signal to the first transmission line; providing a second signal to the second transmission line; detecting an incident edge of the first signal on the first transmission line; detecting a reflected edge of the second signal on the second transmission line; and determining the propagation delay based on times of detection of the incident edge and detection of the reflected edge.