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current, fluid levels, fluid temperatures, distance traveled and feedbacks of various controls
(turn signals, parking brake, headlights, transmission position). Cautions may be displayed for
special problems (fuel low, check engine, tire pressure low, door ajar, seat belt unfastened).
Problems are recorded so they can be reported to diagnostic equipment. Navigation systems
can provide voice commands to reach a destination. Automotive instrumentation must be
cheap and reliable over long periods in harsh environments. There may be independent airbag
systems which contain sensors, logic and actuators. Anti-skid braking systems use sensors to
control the brakes, while cruise control affects throttle position. A wide variety of services can
be provided via communication links.

Early aircraft had a few sensors. "Steam gauges" converted air pressures into needle
deflections that could be interpreted as altitude and airspeed. A magnetic compass provided a
sense of direction. The displays to the pilot were as critical as the measurements. A modern
aircraft has a far more sophisticated suite of sensors and displays, which are embedded into
avionics systems. The aircraft may contain inertial navigation systems, global positioning
systems, weather radar, autopilots, and aircraft stabilization systems. Redundant sensors are
used for reliability. A subset of the information may be transferred to a crash recorder to aid
mishap investigations. Modern pilot displays now include computer displays including head-
up displays. Air traffic control radar is distributed instrumentation system. The ground portion
transmits an electromagnetic pulse and receives an echo (at least). Aircraft carry transponders
that transmit codes on reception of the pulse. The system displays aircraft map location, an
identifier and optionally altitude. The map location is based on sensed antenna direction and
sensed time delay. The other information is embedded in the transponder transmission.
Among the possible uses of the term is a collection of laboratory test equipment.
Laboratory equipment is available to measure many electrical and chemical quantities. Such a
collection of equipment might be used to automate the testing of drinking water for pollutants.
Instrumentation is used to measure many parameters (physical values). In addition to
measuring field parameters, instrumentation is also responsible for providing the ability to
modify some of them.

Instrumentation engineering
Instrumentation engineering is the engineering specialization focused on the principle
and operation of measuring instruments that are used in design and configuration of
automated systems in electrical, pneumatic domains etc. They typically work for industries
with automated processes, such as chemical or manufacturing plants, with the goal of
improving system productivity, reliability, safety, optimization, and stability. To control the
parameters in a process or in a particular system, devices such as microprocessors,
microcontrollers are used, but their ultimate aim is to control the parameters of a system.
Instrumentation engineering is loosely defined because the required tasks are very
domain dependent. An expert in the biomedical instrumentation of laboratory rats has very
different concerns than the expert in rocket instrumentation. Common concerns of both are
the selection of appropriate sensors based on size, weight, cost, reliability, accuracy,
longevity, environmental robustness and frequency response. Some sensors are literally fired
in artillery shells. Others sense thermonuclear explosions until destroyed. Invariably sensor
data must be recorded, transmitted or displayed. Recording rates and capacities vary
enormously. Transmission can be trivial or can be clandestine, encrypted and low-power in
the presence of jamming. Displays can be trivially simple or can require consultation with
human factors experts. Control system design varies from trivial to a separate specialty.
Instrumentation engineers are commonly responsible for integrating the sensors with
the recorders, transmitters, displays or control systems. They may design or specify

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