Variable-Frequency Trigger Threshold for Impulsive Noise Detection
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Solution Overview
Problem
Conventional methods for measuring impulsive noise in digital telecommunications, such as the use of digital oscilloscopes, are inadequate as they require a signal storage trigger threshold above the amplitude of stationary noise, making it impossible to measure impulsive noises with lower amplitudes, which are significant in xDSL and PLT transmissions.
Innovation Solution
A method involving the conversion of signals into the frequency domain to define a frequency-variable trigger threshold, followed by storing and high-pass filtering the signal when the threshold is exceeded, allowing for the measurement of impulsive noise even when its amplitude is lower than that of stationary noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a digital oscilloscope with a fixed trigger threshold above stationary noise is used to measure impulsive noise, then impulsive noise with high amplitude can be detected, but impulsive noise with lower amplitude than stationary noise cannot be measured
Solution Approach 1:
The patent applies dynamics by making the trigger threshold variable rather than fixed. The threshold adapts dynamically based on the measured stationary noise characteristics, allowing the system to detect impulsive noises across a wide range of amplitudes including those below the stationary noise level. This is achieved by continuously analyzing the signal and adjusting the threshold accordingly.
Solution Approach 2:
The patent changes the trigger threshold parameter from a fixed value to a variable that depends on stationary noise characteristics. By making the threshold a function of the measured signal conditions rather than a constant, the system can adapt to different noise environments and detect impulsive noises with varying amplitudes, resolving the contradiction between detection precision and measurement range.
2Measurement precision
If a scanning spectrum analyzer is used to measure stationary noise with high sensitivity, then low-level stationary disturbances can be detected, but impulsive noise varying over time cannot be observed
Solution Approach 1:
The patent segments the noise measurement problem into two distinct components: stationary noise and impulsive noise. By separating the measurement approaches for each type, the system can use high-sensitivity methods for stationary noise while simultaneously detecting temporal variations for impulsive noise, thus resolving the contradiction between sensitivity and response speed.
Solution Approach 2:
The patent employs periodic action by using a sliding window approach that continuously updates the stationary noise characteristics. This periodic reanalysis allows the system to maintain high sensitivity for stationary noise while responding to temporal variations, as the window continuously moves through the signal to detect changes.
3Reliability
If a fixed trigger threshold above stationary noise amplitude is used, then false triggering from stationary noise is avoided, but impulsive noise with lower amplitude than stationary noise cannot be detected
Solution Approach 1:
The patent changes the trigger threshold from a fixed parameter to a dynamic one that adapts to the measured stationary noise characteristics. This allows the threshold to be set just above the actual stationary noise level for each measurement period, maintaining reliability while enabling detection of lower-amplitude impulsive noises that would otherwise be missed.
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 the detection and measurement of impulsive noise with lower amplitudes, crucial for maintaining signal quality in xDSL and PLT transmissions by distinguishing impulsive noise from stationary noise, thereby improving signal reception and allowing for proper error correction and equipment testing.
Implementation Method 1
converting the first signal into the frequency domain; converting the second signal into the frequency domain; According to a preferred characteristic, the conversion of the signal in the frequency domain is carried out by a Fourier transform.
Implementation Method 2
high pass filtering the stored signal
Data Source
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AI summary
The invention relates to a method for measuring impulse noise in a signal, characterized in that it comprises the steps of: measuring (E1) at least one first signal (S); converting (E2) the first signal in the frequency domain; defining (E3) a variable-frequency triggering threshold (M) on the basis of stationary characteristics of the first signal; measuring a second signal (S'); converting the second signal in the frequency domain; storing (E4) the second signal when the second signal reaches or passes the triggering threshold; and high-pass-filtering (E5) the stored signal.