[NRV Rocketry] Telemetry seminar summary

[Jordan Truesdell]

For those of you who may have missed it, Dr. Pat Artis was generous to arrange a 6 hour seminar yesterday on telemetry presented by Glenn Rosenthal of Ulyssix Technologies, one of the premier vendors for telemetry ground station hardware in the Aerospace and Defense sectors. 

Several "adults" and quite a few students were at the seminar to learn about the end-to-end telemery process used in modern flight, as well as get recommendations for commercial hardware vendors for the various components necessary. Glenn also invited us to consider attending the DATT Summit [https://www.dattsummit.com/] in Orlando in June, whis is his brainchild to assist all of the technology sectors in coming together to share best practices and work on collaborative standards for interoperability. 

Glenn walked us through a typical chain of data - from sensor outputs through filters, then to interleaving data and transmission standards, and the techniques for receiving, filtering, decoding, synchronizing, and recording flight data on the ground. He covered the limitations of data - maximum data rates and bandwidth limitations - as well as techniques to increase data density and reliability. 

One large section of the talk was  on the data formatting and synchronization. He covered common ways to format data, placing it into frames with identification headers and data words. He covered how to efficiently interleave data of different rates into a fixed length data stream by commutation of the sensor inputs into the stream - providing multiple readings ("super commutation") of high rate data in each frame, and sending low rate data only once every n frames ("sub-commutation"). 

One large section of the seminar was devoted to different modulation techniques like FM, PSK, and QPSK, as well as modern alterations such as Shaped Modulation QPSK to reduce the necessary power and bandwidth for a given data rate. We also got to see the common oscilloscope patterns for proper reception and how to qualitatively determine the match of incoming signals to the decoding hardware.  This was set within a walk-through of the entire decoder chain - including recommendations to record data at multiple points so that a failure during a live event (either of the system or in the telemetry receiver) could always be investigated using the pre-processed data. 

He closed with different coding types and examples of telemetry formats used in current operational projects from NASA, Military, and private space ventures. All in all it was an excellent overview of the telemetry process and a good primer on setting up your own transmission data format for whatever you'd like to get off of your rocket sensors during flight.  

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Jordan
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