Cable Modem Upstream Signal Fault Detection in HFC Networks
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Solution Overview
Problem
Current cable modem (CM) systems in hybrid fiber coaxial (HFC) networks can only detect two types of noise: intrusion noise outside a carrier and white noise, failing to identify other fault issues such as non-linear distortion, pulse noise, and intrusion noise on a carrier, which affects fault location accuracy and service quality.
Innovation Solution
A CM is enhanced with a collection module that gathers upstream signals using various methods and an analysis module that detects intrusion noise outside a carrier, white noise, non-linear distortion, pulse noise, and linear distortion by employing histogram analysis, band-pass filtering, and spectrum analysis, along with a direction-selective apparatus to isolate upstream signals and determine fault locations accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the CM uses the downstream FBC function to detect upstream signal, then the CM can detect intrusion noise outside carrier and white noise, but it cannot detect other fault problems such as non-linear distortion, pulse noise, and intrusion noise on carrier
Solution Approach 1:
The patent segments the upstream signal detection into multiple specialized detection paths: one path detects intrusion noise outside carrier and white noise using the existing FBC function, while another path detects non-linear distortion, pulse noise, and intrusion noise on carrier using additional processing modules. This segmentation allows each detection path to be optimized for specific noise types without compromising overall detection capability.
Solution Approach 2:
The patent enhances the CM to perform multiple detection functions simultaneously. The upgraded CM can detect various noise types (intrusion noise outside carrier, white noise, non-linear distortion, pulse noise, intrusion noise on carrier) through a unified detection framework that combines the existing FBC function with additional analysis capabilities, making the device universal in handling different fault conditions.
2Measurement precision
If the CMTS tests and analyzes detection results, then the CMTS can detect upstream signal quality deterioration, but it cannot learn of an abrupt point indicating the quality deterioration location
Solution Approach 1:
The patent introduces an intermediary detection mechanism where the CM acts as a local detector that captures upstream signals and identifies abrupt quality deterioration points before reporting to the CMTS. This intermediary approach preserves fault location information that would otherwise be lost in centralized CMTS analysis, enabling precise fault positioning while maintaining comprehensive signal quality monitoring.
Solution Approach 2:
The patent implements preliminary detection at the CM level, where the CM performs initial analysis of upstream signals to identify abrupt quality deterioration points before the signal reaches the CMTS. This preliminary action ensures that fault location information is captured at the source, preventing information loss during centralized processing and enabling faster fault response.
3Adaptability or versatility
If more detection functions are added to the CM, then the CM can detect more noise types, but the device complexity increases
Solution Approach 1:
The patent merges multiple detection functions into a unified CM architecture. Instead of adding separate independent detection devices, the patent integrates noise detection, non-linear distortion detection, pulse noise detection, and carrier intrusion noise detection into a single CM unit, sharing common signal processing resources and reducing overall system complexity.
Solution Approach 2:
The patent designs a universal CM detection framework that handles multiple noise types through a single multi-functional detection system. The CM is upgraded to perform diverse detection tasks (various noise types, distortion detection) using a unified architecture, avoiding the need for multiple specialized devices and reducing system complexity while maintaining comprehensive detection capability.
Data Source
AI summary
A cable modem (CM), a hybrid fiber coaxial (HFC) network fault locating system, and a fault detection method are provided. The CM can not only detect intrusion noise outside a carrier and white noise, but also detect other fault problems, such as non-linear distortion, pulse noise, intrusion noise on a carrier, and linear distortion. The system includes a direction-selective apparatus. The apparatus can allow only an upstream signal entered from an output port of the apparatus to be transmitted to a CM to which a branch port of the apparatus is connected, without allowing an upstream signal entered from an input port of the apparatus to be transmitted to the CM to which the branch port of the apparatus is connected, so that once detecting a fault from the upstream signal, the CM can accurately determine, through locating, that the fault in an HFC network is located on an output port side of the apparatus.