DSL Attenuation Calculation via Low-Frequency Signal Measurement
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Solution Overview
Problem
Current broadband test systems for DSL face challenges in accurately measuring attenuation, particularly at high frequencies and in mixed-diameter lines, due to complex parameter measurements and significant errors in calculating attenuation features.
Innovation Solution
A method that calculates attenuation by sending a low-frequency test signal to measure wire-to-wire capacitance and loop resistance, using constants derived from rough and actual attenuations at a specific frequency, thereby bypassing the need to measure resistance and inductance at high frequencies and simplifying the calculation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the first parameter measurement method is used to calculate attenuation at high frequency, then the attenuation feature can be obtained, but the measurement complexity and error increase significantly
Solution Approach 1:
The patent changes the measurement frequency parameter from high frequency to low frequency. By measuring loop resistance and wire-to-wire capacitance at low frequency where measurements are more accurate and easier to perform, then using calculation formulas to derive the attenuation at the required high frequency, the system avoids the complexity and errors of direct high-frequency parameter measurements while maintaining measurement accuracy
2Measurement precision
If four first parameters (R, L, G, C) are measured at high frequency to calculate attenuation, then the attenuation feature can be obtained, but the measurement process becomes complex and time-consuming
Solution Approach 1:
The patent extracts only the essential parameters needed for attenuation calculation by measuring just two parameters (loop resistance and wire-to-wire capacitance) at low frequency, rather than measuring all four first parameters (R, L, G, C) at high frequency. This reduction in measurement requirements significantly decreases measurement time and complexity while still enabling accurate attenuation calculation through the provided formulas
3Ease of operation
If TDR method is used to measure attenuation, then the measurement process is simplified, but the accuracy decreases at high frequencies
Solution Approach 1:
The patent introduces calculation formulas as an intermediary between low-frequency measurements and high-frequency attenuation results. By using mathematical relationships to transform low-frequency measured values into high-frequency attenuation predictions, the system maintains the operational simplicity of low-frequency measurement while achieving high-frequency measurement accuracy that TDR cannot provide
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 reduces measurement errors and simplifies the broadband test system, enabling accurate attenuation calculation for both uniform and mixed-diameter lines, while reducing costs and complexity.
Implementation Method 1
measuring a wire-to-wire capacitance and a loop resistance of the line according to the low-frequency signal
Implementation Method 2
measuring a wire-to-wire capacitance and a loop resistance of the line according to the low-frequency signal
Data Source
Figure 1~2
AI summary
A method for measuring line attenuation of digital subscriber line includes: sending a low-frequency test signal into the line and measuring a wire-to-wire capacitance and a loop resistance of the line; calculating an actual attenuation of the line based on the wire-to-wire capacitance, the loop resistance and a first frequency; calculating an attenuation of the line at a test frequency based on the actual attenuation of the line at the first frequency, the first frequency and the test frequency. In the method provided by the embodiments of the present invention, the four first parameters R(f), L(f), G and C at the given frequency f are not measured and the tough measurement process may thus be avoided. Furthermore, the line attenuation may be calculated based on the loop resistance and the wire-to-wire capacitance at a low frequency according to embodiments of the present invention, and consequently the broadband test system may be simplified to a great extent and the cost thereof may be reduced.