Non-Invasive Transmission Path Fault Detection Using Capacitive Pickup
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Solution Overview
Problem
Existing methods for testing transmission paths on printed circuit boards are invasive, costly, and complex, especially when dealing with open circuit faults across multiple field replaceable units, requiring additional traces or sophisticated circuitry, which can disrupt normal operations and are difficult to implement in existing designs.
Innovation Solution
A non-invasive method involving a low-frequency test signal injected at a first location on the transmission path, capacitively coupled to a pickup line at a second location, allowing for fault detection without altering the transmission path, using a JTAG interface and phase-sensitive detection to identify signal presence or absence, enabling accurate fault localization within a single FRU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional traces are added to monitor signals on transmission paths, then fault detection capability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent introduces an intermediary pickup line that is capacitively coupled to the transmission path. This pickup line acts as a mediator to detect signals on the transmission path without requiring direct electrical connection or additional traces on the PCB. The intermediary approach allows fault detection while maintaining the original PCB layout integrity.
Solution Approach 2:
The patent replaces the mechanical/physical approach of adding traces with an electromagnetic field-based approach. By using capacitive coupling and electromagnetic induction, the system can detect signals wirelessly through the PCB structure, eliminating the need for physical trace modifications.
2Measurement precision
If sophisticated circuitry is added for testing transmission paths, then fault detection accuracy is improved, but ease of manufacture and implementation deteriorate
Solution Approach 1:
The transmission path itself serves as the test object and the signal source. The normal operational signals on the transmission path are used to detect faults, eliminating the need for separate test equipment or complex testing circuitry. The system tests itself using its own operational signals.
Solution Approach 2:
The pickup line serves as a simple intermediary that passively couples to the transmission path through capacitance. This simple structure requires no active components, amplifiers, or complex circuitry, making it easy to manufacture and implement while still providing accurate fault detection.
3Measurement precision
If additional testing components are added, then fault localization precision is improved, but loss of substance and cost increase
Solution Approach 1:
The pickup line structure can be universally applied to multiple transmission paths and serves multiple functions: signal detection, fault localization, and system diagnostics. This multi-functional approach eliminates the need for separate testing components for each transmission path, reducing overall component quantity and cost.
Solution Approach 2:
The capacitive coupling mechanism provides a low-cost intermediary solution that requires minimal materials. The pickup line can be implemented as a simple conductive trace or strip that couples to existing transmission paths, avoiding the need for expensive specialized testing components.
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 approach allows for efficient, cost-effective fault detection and localization in a noisy environment, reducing the need for additional components and minimizing disruption to normal operations, facilitating targeted repairs and system reconfiguration.
Implementation Method 1
providing a pickup line capacitively coupled at a second location to the transmission path
Data Source
AI summary
One embodiment of the invention provides apparatus and a method for testing a transmission path across one or more printed circuit boards. According to the method, a test signal is presented at a first location on the transmission path. The test signal is generally low frequency compared to normal data communications on the transmission path. A pickup line is capacitively coupled at a second location to the transmission path. The pickup line is monitored with a detector to see whether or not the test signal is present. If the test signal is not present, it is determined that there is a fault on the transmission path between the first location and the second location.