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Telemetry Transmitters
Telemetry or "remote measurement" is a highly automated
communications process by which measurements are made and other data
collected at remote, inaccessible or dangerous places, and then
relayed by a telemetry transmitter to receiving stations for
display, monitoring, and recording. The original telemetry systems
were termed "supervisory" because they were used to monitor electric
power distribution. Communication channels form a major part of any
telemetry system, as it involves measurement of the transmission of
data over various mediums.
Telemetry transmitter is the instrument used for recording the
readings of an instrument and transmitting them by radio or wireless
frequencies. Technically, when relaying data, it is necessary for
the transmitter to identify the data item corresponding to each
segment of the bit stream. This is done by inserting a
synchronization bit string into the telemetry stream on a regular
basis, usually at the beginning or end of each repeating cycle. This
generally corresponds to the beginning or end of a minor or major
frame of telemetry data.
Aerospace telemetry initiated in the 1930s with the radiosonde, a
instrument that automatically measured atmospheric temperature,
pressure and humidity by means of a small, expendable telemetry
transmitter from a balloon high in space, and relayed the data back
to Earth using radio signals. These days, telemetry is used in
testing of moving vehicles such as cars, aircrafts, missiles and
satellites. National Aeronautics and Space Administration (NASA),
European Space Agency (ESA) and other international space agencies
use telemetry transmitter for data collection and transmission from
orbiting spacecrafts and satellites.
Wireless networking without the encumbrance and restriction of wires
connecting the transmitter and receiver has catapulted the potential
applications of telemetry. Major applications of telemetry includes
automatic monitoring of large, complex systems such as satellites,
chemical plants, oilrigs, electric power plants, gathering
meteorological data, remote meter reading, logistics management,
tracking endangered land and marine species, real time physiological
monitoring of patients, and monitoring manned and unmanned space
flights.
Winston Churchill once said, "The price of greatness is
responsibility." In the same manner, this great technology should be
used responsibly. For instance, for many environmental monitoring
duties, such as stream gauging or automatic weather stations, the
measurement values are unlikely to change significantly for many
hours at a time. In such cases, it would be grossly uneconomical in
terms of both electrical power and use of spectrum space to run the
telemetry transmitter continuously.
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