PNNL

Abstract

This document describes the development of a field programable gate array (FPGA) radio frequency system on a chip (RF SoC) adaptation and evaluation of the single-board device to perform both Frequency Domain Reflectometry (FDR) and Spread Spectrum Time Domain Reflectometry (SSTDR) for offline and online cable testing. The work builds on and leverages the work of Pacific Northwest National Laboratory (PNNL) in airport millimeter wave technology by using the same development hardware employed in that program. The work is performed under sponsorship from the U.S. Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) program and the task objective is to confirm and demonstrate feasibility to adapt FPGA technology for a cost-effective multiplexed single-board electronic module to perform cable tests that are equivalent to commercial and laboratory test instruments for FDR and SSTDR cable tests. The developed 2-channel (extendable to 7 channels) system was compared to dedicated and proven test instruments and shown to produce equivalent results on a range of cables and with a range of damage types. The FPGA reflectometry test board is one of several technologies that could facilitate implementation of online monitoring of safety critical cable systems. Other required tools include: • Coupling technology (inductive or capacitive) that can protect the test instruments from damage from high voltage levels (up to 2000 VAC for low voltage systems and 15kV for medium voltage nuclear power plant applications). • Automatic measurement analysis to recognize cable damage and degradation. Note that reflectometry signals are complex and not well suited for simple threshold alarms. Advanced signal processing approaches like baseline reference signal subtraction and machine learning based on a library of training data will be required for practical applications. PNNL and others have worked on and are continuing development to make these kinds of tools available for a complete online monitoring system. The FPGA system architecture, including hardware description and an outline of the software, are described within this report. The complete copyright-protected software is provided in an appendix such that one skilled in FPGA development could replicate the developed system.