Telemetry is
the process by which an object’s characteristics are measured (such
as velocity of an aircraft), and the results transmitted to a distant
station where they are displayed, recorded, and analyzed. The transmission
media may be air and space for satellite applications, or copper wire
and fiber cable for static ground environments like power generating
plants.
In today's telemetry applications, which support large
numbers of measurands,
it is too costly and impractical to use separate transmission channels
for each measured quantity. The telemetry process involves grouping measurements
(such as pressure, speed, and temperature) into a format that can be
transmitted
as a single data stream. Once received, the data stream is separated
into the original measurement’s components for analysis.
Telemetry lets you stay in
a safe (or convenient) location while monitoring what's taking place
in an unsafe (or inconvenient)
location. Aircraft development, for example, is a major application for telemetry systems.
During initial flight testing, an aircraft performs a variety of test
maneuvers. The critical flight data from a maneuver is transmitted
to
flight test engineers at a ground station where results are viewed in
real time or analyzed within seconds of the maneuver. Real-time monitoring
allows the "safety officer" to make instant decisions on
whether to proceed with or terminate a test. With real-time analysis,
the flight
test engineer can request a maneuver be repeated, the next maneuver be
performed, or test plan alternatives be substituted. Real-time data
is
also captured to storage media, such as disk and tape, for later analysis
and archiving.
 
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