PIM Fault Location via Segmented Signal Reflection Analysis

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Solution Overview

Problem

Conventional methods for diagnosing passive intermodulation (PIM) faults in coaxial cable networks are inefficient, as they only measure overall PIM levels and do not provide location information, requiring labor-intensive percussive testing or disassembly of network components, which are time-consuming and often inaccurate.

Innovation Solution

A test module connected to a PIM analyzer that applies test signals to the network, uses directional couplers and receivers to measure phase offsets, and a control module to convert and store signal data for processing, enabling the estimation and display of PIM source locations and magnitudes within the network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional two-tone test methods are used to measure PIM levels, then overall PIM measurement is achieved, but location information of PIM sources is not provided

Engineering Contradiction:

ImprovePIM level measurementVSAvoidlocation information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent segments the cable network into multiple sections by injecting test signals at different known locations and measuring the reflected signals. This segmentation allows the system to identify which specific section contains the PIM source, thereby providing location information that was previously lost in conventional overall measurement methods.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces time-domain reflectometry as an intermediary measurement technique that bridges the gap between PIM level measurement and location identification. By using reflected signal analysis, the system can determine the distance to PIM sources without requiring physical access or disassembly of network components.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of information

If percussive testing or disassembly methods are used to locate PIM faults, then location information may be obtained, but diagnostic time and labor are significantly increased

Engineering Contradiction:

Improvelocation informationVSAvoiddiagnostic time

Core Design Contradiction:

Loss of informationVSLoss of time

Solution Approach 1:

The patent replaces mechanical diagnostic methods (percussive testing, disassembly, and physical inspection) with electrical measurement techniques. By using reflected signal analysis and time-domain reflectometry, the system can locate PIM sources remotely without physical contact or disassembly, dramatically reducing diagnostic time and labor requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system enables the cable network itself to provide location information through its reflected signals. The PIM sources and cable characteristics naturally produce reflected signals that contain location data, eliminating the need for external mechanical probing or disassembly methods.

Inventive Principle:

Principle #25Self-service

3Loss of information

If percussive testing or disassembly methods are used to locate PIM faults, then location information may be obtained, but measurement accuracy is reduced

Engineering Contradiction:

Improvelocation informationVSAvoidlocation accuracy

Core Design Contradiction:

Loss of informationVSMeasurement precision

Solution Approach 1:

The patent uses feedback from reflected signal measurements to continuously refine the location estimation of PIM sources. By analyzing the timing and characteristics of reflected signals and comparing them with known cable parameters, the system can accurately determine PIM source locations without the disturbances introduced by mechanical testing methods.

Inventive Principle:

Principle #23Feedback

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 solution allows for reliable and accurate detection of PIM sources, reducing diagnostic time and labor by providing precise location and magnitude data, improving the efficiency of fault identification in communications networks.

Implementation Method 1

uses directional couplers and receivers to measure phase offsets

Methodology Applied

Scientific EffectDirectional coupling:

Implementation Method 2

a phase detector coupled to the primary receiver and reference receiver, said phase detector being operable to measure phase offsets between the plurality of primary return signals and the plurality of reference signals

Methodology Applied

Scientific EffectPhase detection:

Implementation Method 3

Passive intermodulation distortion (PIM) is a form of electromagnetic interference that is often encountered in radio communications systems

Methodology Applied

Scientific EffectPassive intermodulation:

Data Source

PatentEP2689544B1System and apparatus for locating faults in a cable network

Publication Date: 2017.09.27 KAELUS

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AI summary

A range to fault (RTF) module (100) for use in a system for locating faults in a cable network is discussed. The module includes an input port (101) for coupling the module to a PIM analyser. The module (100) also includes an output port (102) for connection to the device under test (DUT). In addition to the input (101) and output (102) ports the module is provided with a monitor port (103) for receipt of a PIM signal from the PIM analyser. The module in this instance also includes two USB ports (104a), (104b) enabling a serial connection between the PIM analyser and the module (100).