Hybrid Fiber Coax Test Instrument for RFOG Signal Conversion
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Solution Overview
Problem
The transition from hybrid fiber coax (HFC) to IP-based fiber networks, such as EPON or GPON, requires incremental steps to minimize capital expenditures, and existing technologies lack effective tools for testing and verifying the performance of Radio Frequency over Glass (RFOG) systems, which integrate fiber optics with traditional coaxial equipment.
Innovation Solution
A test instrument with circuitry to test RF and RFOG installations, capable of converting optical signals back to RF for performing DOCSIS and RF signal tests, including level, scan, carrier-to-noise, digital MER/BER, and full communication with CMTS, allowing technicians to verify proper operation and compatibility with existing HFC equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RFOG technology is implemented to replace coax with fiber, then noise susceptibility is reduced and usable RF spectrum is increased, but existing test instruments cannot effectively test or verify RFOG system performance
Solution Approach 1:
The test instrument is designed with multi-functionality to handle both traditional HFC and new RFOG systems. It includes an optical node unit that can convert optical signals to RF signals, enabling the instrument to test RFOG installations while maintaining compatibility with existing HFC testing capabilities. This universal design allows a single instrument to serve multiple testing purposes across different network architectures.
Solution Approach 2:
The optical node unit acts as an intermediary component that bridges the gap between optical RFOG signals and traditional RF testing equipment. By converting optical signals to RF signals, it enables existing RF test circuits to evaluate RFOG system performance without requiring complete redesign of the test instrument architecture.
2Loss of energy
If incremental transition from HFC to fiber is used, then capital expenditures are reduced, but new testing capabilities are needed to verify RFOG installations
Solution Approach 1:
The patent merges RFOG testing capabilities with existing HFC testing functions in a single integrated instrument. The optical node unit is incorporated into the existing test instrument architecture, combining optical-to-RF conversion functionality with traditional RF measurement circuits. This merging approach adds RFOG testing capability without requiring completely separate testing equipment, thereby limiting the increase in device complexity.
3Reliability
If RFOG systems use optical signals converted to RF, then performance is improved, but specialized test equipment is required that does not yet exist
Solution Approach 1:
The test instrument performs self-service by including an integrated optical node unit that automatically converts optical signals to RF signals for testing. This self-contained design eliminates the need for external optical-to-RF conversion equipment, making the instrument easier to manufacture and deploy as a complete, ready-to-use solution for RFOG system verification.
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 efficient testing and validation of RFOG systems, ensuring they operate within the proper power range and perform standard cable TV tests, facilitating seamless integration with existing infrastructure while reducing noise susceptibility and increasing usable RF spectrum.
Implementation Method 1
An Optical Node Unit ("ONU") 26 located at, for example, the subscriber's premises 14, is used to convert this laser wavelength to RF/coax signals for use in the coax cables 18 and the equipment 20
Implementation Method 2
The RFOG system 10 includes a transmitter 22 and a receiver 24 at the headend 12 that converts all of the RF signals to/from a modulated laser wavelength
Data Source
AI summary
A test instrument for testing RF and RFOG installations is disclosed. The test instrument is configured to test RFoG downstream power and recover an original RF signal from an optical signal generated at a head end and perform DOCSIS and RF signal tests including level, scan, carrier to noise, digital MER/BER, and full communication with CMTS.