What is span drift?

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Multiple Choice

What is span drift?

Span drift is a change in the full-scale output of a measurement device over time. The span, or full-scale range, reflects the device’s gain—the relationship between input and output at the top end of the scale. When span drifts, that gain shifts, so the maximum input no longer maps to the original full-scale output. As a result, readings across the range become systematically too high or too low relative to the true value, lowering overall accuracy. Think of a sensor calibrated to 0–100 units. If the span drifts, the 100-unit input might now produce an output that corresponds to something above or below 100, and every other reading is scaled accordingly. Zero drift, by contrast, would shift the reading at zero input (an offset) rather than changing the full-scale mapping. Noise is random fluctuations, not a consistent change in the scale. Environmental changes can cause drift, but the term specifically describes this change in the device’s full-scale, or gain, behavior.

Span drift is a change in the full-scale output of a measurement device over time. The span, or full-scale range, reflects the device’s gain—the relationship between input and output at the top end of the scale. When span drifts, that gain shifts, so the maximum input no longer maps to the original full-scale output. As a result, readings across the range become systematically too high or too low relative to the true value, lowering overall accuracy.

Think of a sensor calibrated to 0–100 units. If the span drifts, the 100-unit input might now produce an output that corresponds to something above or below 100, and every other reading is scaled accordingly. Zero drift, by contrast, would shift the reading at zero input (an offset) rather than changing the full-scale mapping. Noise is random fluctuations, not a consistent change in the scale. Environmental changes can cause drift, but the term specifically describes this change in the device’s full-scale, or gain, behavior.

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