Which of the following describes common noise sources in instrumentation loops and typical mitigation strategies?

• A. Power supply noise, EMI, sensor thermal noise, ground loops; mitigations: shielding, proper grounding, twisted-pair, filtering, stable power.
• B. Only EMI and wiring length.
• C. Temperature drift only.
• D. Data processing delays.

Answer: (A)

Noise in instrumentation loops comes from multiple sources along the signal path and environment, and effective mitigation targets both the sources and how the signal is carried. The best choice lists several common culprits—power supply noise, electromagnetic interference, sensor thermal (Johnson) noise, and ground-loop currents—which are typical in real loop installations. It also pairs practical fixes: shielding to block radiated noise, proper grounding to prevent unwanted current paths, twisted-pair wiring to cancel common-mode noise on differential signals, filtering to remove high-frequency junk, and using a stable power supply to minimize ripple that can modulate the signal. The other options are too narrow: EMI and wiring length omit other noise sources and remedies; temperature drift alone misses many contributors; and data processing delays aren’t intrinsic to the noise within the loop itself.