Intermodulation Fault Location in RF Signal Paths
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Solution Overview
Problem
Current methods for locating faulty points in radio-frequency signal transmission paths with non-linear transmission characteristics are limited by bandwidth constraints and complexity, leading to inaccurate fault location and resolution.
Innovation Solution
A method involving the generation of a first RF signal with a carrier frequency and a digital signal, introduction of these signals into the transmission path, reception of an intermodulation product, demodulation to recover the digital signal, and calculation of the time shift to determine the faulty point's location, allowing precise fault location without complex apparatus or operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PIM measurement methods are used with multiple RF signals and cross-correlation, then intermodulation products can be located, but the measurement complexity increases significantly and resolution becomes insufficient
Solution Approach 1:
The patent extracts only the necessary information (time shift between original and recovered digital signals) from the intermodulation measurement process, eliminating the need for complex multi-signal generation and cross-correlation operations. This focuses the measurement on the essential parameter for fault location while discarding unnecessary complexity.
Solution Approach 2:
Instead of generating multiple RF signals and deriving intermodulation products through complex processing, the patent inverts the approach by injecting a single modulated RF signal and recovering the digital signal from the intermodulation product. This reverse methodology simplifies the measurement system while maintaining or improving resolution.
2Measurement precision
If bandwidth-limited frequency modulation is used for distance measurement, then the measurement can be performed within transmission constraints, but the fault location resolution is limited
Solution Approach 1:
The patent changes the measurement parameter from frequency-modulated distance measurement to time-shift measurement of digital signals. By measuring the time shift between the original and recovered digital signals, the system achieves higher resolution fault location while adapting to bandwidth constraints through efficient signal processing rather than broad frequency sweeps.
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
Enables precise and simplified fault location in radio-frequency signal transmission paths by determining the time shift between the original and recovered digital signals, improving resolution and reducing measurement complexity.
Implementation Method 1
through intermodulation, two transmission signals with two different carrier frequencies which are generated with high power in a BTS generate interfering signals at points with non-linear transmission behavior
Data Source
AI summary
A method for intermodulation measurement for locating points in a signal transmission path for a high-frequency signal that are faulty with regard to HF transmission properties of the signal transmission path, by generating a first HF signal uTest, having a carrier frequency f1 and a digital signal uCode modulated thereon; generating a second HF signal u2 having a frequency f2; introducing the first HF signal uTest and the second HF signal u2 into the signal transmission path at a predetermined introduction point; receiving an intermodulation product, which is generated in the signal transmission path from the first HF signal and the second HF signal at at least one faulty point, as an intermodulation product signal uRX; recovering a digital signal udemod from uRX; and determining a time shift tx between the digital signal uCode and the recovered digital signal udemod. The invention further relates to a measuring device for performing this method.