Balanced Line Imbalance Detection Using Sine Wave Bursts
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Solution Overview
Problem
Conventional methods for detecting imbalances in paired lines, especially those affected by high power influence, fail to accurately identify subtle imbalances in the DSL band, leading to erroneous readings and misidentification of noise sources, which complicates the location and repair of faults.
Innovation Solution
A portable apparatus with a balanced ac current source and differential amplifier circuit that uses sine wave bursts to detect imbalances across paired lines, providing a numeric readout and adjustable bandpass filtering to isolate noise sources in the DSL and VDSL bands, even in the presence of high power influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection devices are used to measure pair balance, then the devices can detect imbalances in the absence of power influence, but they fail to accurately detect imbalances when high power influence is present
Solution Approach 1:
The detection device uses periodic sine wave bursts at specific frequencies (e.g., 200 kHz, 1 MHz) to excite the paired line. By using periodic signals with defined frequency and duration, the device can distinguish between power influence (typically 50/60 Hz) and actual pair imbalances through frequency domain analysis, thereby maintaining measurement accuracy in the presence of power influence.
Solution Approach 2:
The invention introduces an intermediary detection mechanism that measures the conversion of simplex signals to metallic signals. Instead of directly measuring the imbalance, the device uses a balanced center-tapped termination to convert unbalance into measurable metallic voltage, which can then be analyzed to detect faults even when power influence is present.
2Reliability
If conventional passive detection devices are used, then they can detect existing noise, but they cannot generate longitudinal current flow needed to detect series resistance faults
Solution Approach 1:
The detection device performs preliminary action by actively generating sine wave bursts through a balanced center-tapped termination before measuring the response. This active excitation creates the necessary longitudinal current flow that would otherwise be absent, enabling the detection of series resistance faults that passive devices cannot detect.
Solution Approach 2:
The device uses its own internal signal generation capability to create the test signal and measure the response in a self-contained manner. The balanced termination and signal generator work together to automatically establish the conditions needed for detecting series resistance faults without requiring external current sources.
3Measurement precision
If voiceband tests are used to detect imbalances, then they can detect obvious faults, but they cannot detect subtle imbalances that affect higher frequencies in ADSL and VDSL circuits
Solution Approach 1:
The invention changes the frequency parameter of the test signal from voiceband frequencies to higher frequencies (e.g., 200 kHz, 1 MHz) that are relevant to ADSL and VDSL operations. By adjusting the frequency parameter of the sine wave bursts, the device can detect subtle imbalances that only manifest at higher frequencies, thereby improving both detection sensitivity and frequency range coverage.
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
The apparatus accurately detects and isolates noise-creating imbalances in paired lines, providing a reliable numeric confirmation of pair balance and facilitating the identification of service-affecting issues in the DSL band without requiring the line to be taken out of service, thus improving fault detection and repair efficiency.
Implementation Method 1
a balanced center tapped termination consisting of precisely equal resistor pairs whose purpose is to drive precisely equal test currents into both sides of the tested pair with respect to ground
Implementation Method 2
The internal circuit comprises a differential amplifier which is connected to the measuring leads across a pair of voltage inlet pathways
Data Source
AI summary
A device for measuring and isolating noise-creating imbalances in a paired telecommunications line has an internal circuit which comprises a balanced center tapped termination consisting of precisely equal resistor pairs. The circuit includes an adjustable sine wave burst generator which generates a low voltage longitudinal ac signal that is transmitted across the balanced pathways. A differential amplifier in the circuit measures this difference and displays it in units of noise or balance. The output of the differential amplifier is transmitted to an analog-to-digital converter. A microprocessor collects the samples in an array, and filters the results for presentation on a display. Advantageously, the microprocessor provides for adjustable and selectable bandpass filtering. Preferred bandpass filtering preferably occurs at 1 kHz, 200 KHz, 1 MHz, and 5 MHz with a preferred frequency bandpass of 3 harmonics to provide bandpass ranges of 200-600 KHz, 1-3 MHz, and 5-15 MHz, respectively, and a bandpass of 3 Hz at 1 kHz.