Question

Change in signal over long period of time is called

• A. \( \text{Noise} \)
• B. \( \text{Offset} \)
• C. \( \text{Hysteresis} \)
• D. \( \text{Drift} \)

Hint:

Drift is a common issue in many electronic systems and sensors. It can significantly affect the accuracy of measurements over extended periods. Regular calibration and using components with good long-term stability are crucial to minimize drift. In some applications, software compensation algorithms are used to counteract the effects of drift.

Answer 1

The Correct Option is D

To solve this problem, let's analyze the given options and understand which term correctly describes a change in signal over a long period of time.

1. Understanding the Key Concept

The question asks about a change in signal over a long period of time. This refers to a gradual, persistent change in a signal's baseline or output that occurs slowly over extended durations (hours, days, or longer).

2. Analysis of Each Option

a) Noise:

• Refers to random fluctuations in a signal
• Occurs over short time scales (milliseconds to seconds)
• Does not describe systematic long-term changes

b) Offset:

• A constant deviation from the expected value
• Remains stable over time once established
• Does not represent gradual change

c) Hysteresis:

• Dependence of output on the history of inputs
• Manifests during cyclic changes, not over long periods
• Not related to time-dependent signal changes

d) Drift:

• Gradual change in signal output over time
• Can be caused by aging components, temperature effects, or material changes
• Exactly matches the description in the question

3. Why Drift is the Correct Answer

Drift specifically refers to:

• Slow, often undesirable changes in instrument characteristics
• Changes that occur over hours, days, or longer
• Can affect both zero point (zero drift) and sensitivity (span drift)

4. Practical Examples of Drift

• Thermocouple output changing over months due to material degradation
• Pressure sensor baseline slowly shifting over years of use
• Electronic circuits changing characteristics with temperature variations

5. Importance in Measurement Systems

Understanding drift is crucial because:

• It affects measurement accuracy over time
• Requires periodic recalibration of instruments
• Must be considered in long-term monitoring applications

6. Final Answer

The correct term is Drift, as it specifically describes a change in signal over a long period of time.