A Synergistic Test Flight: Smart Sensors, EQDR and PCM Backfill

Abstract

This is the story of three projects, which use three different research funding sources, coming together to demonstrate a small, but complete, instrumentation system that advances several technologies. The Onboard Smart Sensor (OSS) project is a Small Business Innovation Research (SBIR) project that incorporates IEEE 1451.4 sensors into an existing Common Airborne Instrumentation System (CAIS) based instrumentation system. These sensors are "smart" in that they can self-identify basic information via a Transducer Electronic Data Sheet (TEDS). The Enhanced Query Data Recorder (EQDR) is being developed under the T&E Science & Technology Spectrum Efficient Technology (S&T SET) portfolio. This recorder is based on the integrated Network Enhanced Telemetry (iNET) specifications. One of the objectives of iNET is to be able to query a recorder in real-time and transfer the request across a network telemetry link. The third project provides Pulse Code Modulation (PCM) backfill to compensate for dropouts. One of the envisioned applications enabled by the iNET architecture is the ability to provide PCM displays in the control room that do not have dropouts. This is called PCM Backfill. The basic scenario is that PCM is both transmitted (as it traditionally has been via serial streaming telemetry (SST)) and recorded onboard. When dropouts occur, a request over the telemetry network is made to the recorder (the EQDR in this case) and the dropped portions of the PCM stream are sent over the telemetry network to backfill the ground display. By adding a PCM-to- Ethernet/iNET bridge, the OSS and legacy instrumentation system can provide data to both the standard PCM and to the EQDR. Combined, this mini-system demonstrates a vision of having intelligence and networking ability across the entire instrumentation system – from sensor to display.