Define a sensor's span and its importance in DDC calibration.

• A. Span is the difference between the sensor's calibrated high and low outputs; it defines range and affects accuracy across the measurement range.
• B. Span is the physical length of the sensor.
• C. Span is the time taken to respond.
• D. Span is the electrical resistance range.

Answer: (A)

In DDC calibration, span is the difference between the sensor’s calibrated high-output value and its calibrated low-output value. This defines the conversion range from the sensor’s raw signal to the measured engineering units and sets the slope of the transfer function. A properly set span uses the available ADC range effectively, giving good resolution and accuracy across the whole measurement span. If the span is too small, high measurements push to the top end and lose accuracy; if too large, low measurements sit too near the bottom with poor resolution. The other options describe physical length, response time, or resistance range, none of which define the calibrated output range or the conversion slope.