Page 46 - Understanding Automotive Electronics

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THE SYSTEMS APPROACH TO CONTROL AND INSTRUMENTATION 2

to a proportional electrical signal continuously. That is, as the input quantity
varies, the sensor output voltage varies proportionately. In mathematical terms,
letting x be the amplitude of the input quantity (e.g., pressure, displacement, or
temperature), the output voltage of an ideal sensor (denoted v) is continuously
proportional to x :

v = k x
s
In this expression, k represents the so-called transducer gain of the sensor.
s
Figure 2.2 illustrates the operation of an ideal pressure sensor, in which x
is the pressure of a fluid and v is the sensor output voltage. The graph seen in
Figure 2.2a shows this pressure as it varies with time; Figure 2.2b shows the
corresponding ideal sensor output voltage. In this example, at every instant of

Figure 2.2
Ideal Pressure Sensor

UNDERSTANDING AUTOMOTIVE ELECTRONICS 33