What is a consequence of signal noise on measurement loops?

What is a consequence of signal noise on measurement loops?

• A. Cleaner readings
• B. Unstable loops
• C. Higher data accuracy
• D. Faster loop response

Answer: (B)

Signal integrity in a measurement loop is the key idea here. Noise adds small, random fluctuations to the loop current. Since the 4–20 mA signal encodes the process variable, those fluctuations make the readout jump around instead of staying steady, so the loop appears unstable. Noise doesn’t improve readings or speed; it actually reduces precision and can cause misleading values or require filtering, which may add lag. So the most accurate consequence is that the loop becomes unstable.

Signal integrity in a measurement loop is the key idea here. Noise adds small, random fluctuations to the loop current. Since the 4–20 mA signal encodes the process variable, those fluctuations make the readout jump around instead of staying steady, so the loop appears unstable. Noise doesn’t improve readings or speed; it actually reduces precision and can cause misleading values or require filtering, which may add lag. So the most accurate consequence is that the loop becomes unstable.