Implementing TmNS Data On Demand

Abstract

The Telemetry Network Standard (TmNS) was released as part of the 2017 version of the IRIG-106 standards. Traditionally, serial streaming telemetry data has been sent on a unidirectional link from the test article to the ground. The TmNS standard offers a new approach to acquiring flight test instrumentation (FTI) data that changes this paradigm by allowing the use of bi-directional data links. These bi-directional links allow for commands and requests to come from the ground back to the aircraft. This offers a new capability to the flight test community to request data on demand from the flight test recorder. One of the longest-standing problems with traditional telemetry has been data dropouts. These gaps in the flight test data can occur at any point in a test flight, and they can prevent the ground controllers from knowing if a test was successfully completed. TmNS offers a solution to this problem by allowing the ground to request a PCM backfill to re-send the section of the data that was lost. This paper explores a fully functional demonstration system that Curtiss-Wright has created to show an end-to-end PCM backfill operation using a TmNS compliant recorder, two TmNS radios, and the IADS real-time visualization and analysis software.