ABSTRACT
A transducer senses the magnitude or intensity of the controlled output and produces a proportional signal in an energy form suitable for transmission along the feedback path to the comparator. [The term proportional is used loosely here because the output of the transducer may not always be directly proportional to the controlled output; that is, the transducer may not be a linear component. In linear systems, if the output of the transducer (the measurement) is not linear, it is linearized by the signal conditioner.] The element of the transducer which senses the controlled output is called the
sensor
; the remaining elements of a transducer serve to convert the sensor output to the energy form required by the
feedback path
. Possible configurations of the feedback path include:
• Mechanical linkage
• Fluid power (pneumatic or hydraulic)
• Electrical, including optical coupling, RF propagation, magnetic coupling, or acoustic propagation
Electrical signals suitable for representing measurement results include:
• DC voltage or current amplitude
• AC voltage or current amplitude, frequency, or phase (CW modulated)
• Voltage or current pulses (digital)
In some cases, representation may change (e.g., from a DC amplitude to digital pulses) along the feedback path.
