= Telemetry
<Telemetry> transmits measurements from a remote system to a receiving system. A useful telemetry chain connects a <sensor>, signal conditioning, a <data converter>, an encoding and transmission system, and a receiver that reconstructs the reported quantities. Calibration, units and the time of measurement remain part of the scientific meaning of the received data.
Spacecraft illustrate why these stages are distinct. NASA's guide describes science and engineering measurements carried by a modulated downlink, then separated on the ground using their positions in frames or identifying information in packets. Locking a receiver onto the radio carrier is different from recognizing the data frames reliably.<Basics of Space Flight (2017 edition) by Dave Doody>[Chapter 10, Uplink and Downlink; Multiplexing; Telemetry Lock; Channelization]{ref}
For an original rate calculation, $n$ channels sampled at $f_s$ readings per second with $b$ transmitted <bits> per reading require at least $nbf_s$ bits per second for the raw measurements. Sixteen channels with twelve-bit readings at $100$ readings per second require $19{,}200$ bits per second before framing and other overhead. The receiving display must also distinguish the sample <time> from arrival <time>: transport delay and missing records otherwise make a remote process appear to evolve differently from the measured one.
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