hysteresis
PrintThe change in the value measured by an instrument or a device, when the direction of the applied signal is changed. For example, the fuel gage of a car may show a lower value when the tank is filled to half level, than when the tank is gradually emptied to half level due to driving for a period of time. Hysteresis due to looseness in mechanical joint is also called backlash.
Hysteresis is often used in the trigger circuitry of digitizers. If, for example, the trigger level is set to 2.0 V with a positive slope, a hysteresis is often added to reduce false triggering due to noise. In this example, if a hysteresis is set from 1.9 to 2.0 V, then the trigger will only activate once when passing 2.0 V with a positive slope. Even if the voltage drops to 1.95 V, and then rises above 2.0 V again, triggering will not occur again. Hysteresis requires that the voltage first drop below 1.9 V, and then again cross 2.0 V before triggering will be activated. This means that the trigger circuitry can tolerate a maximum noise voltage of just below 0.1 V peak-to-peak without any false triggers.
Units:
volt or %
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