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Edited by WisdomAugust at 2018-5-10 08:59
Analog and Digital signals
All the signals examined until now are analog signals, they are uninterrupted signals. The values
of their voltage changes through time by some rule or randomly. As an example for a complex
analog signal the lambda sensor (O2 sensor) signal can be mentioned.
A waveform of digital signals switches between two voltage levels representing the two states of
a Boolean value (0 and 1), even though it is an analog voltage waveform, since it is interpreted in
terms of only two levels – high and low, on and off. Such voltage levels are called Logic voltage
levels. In most cases, the logical levels have constant voltage values: +5V and 0V for example.
Digital signals are generated by switches. These switches are represented by transistors
switching between “open/closed” states. Sometimes digital signals are generated by mechanical
switches, electromechanical relays. An example of digital signals in the automobile electronic is
the Hall sensor, the throttle end position sensors; the closed throttle position sensor (CTPS), the
wide open throttle (WOT) sensor and the data transfer signals between the different ECUs. As
the analog signals digital signals can be periodical and non-periodical.
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