Red Seal Electrician Practice
Signalling and communicationQuestion 121 of 1506

Why is the A/D conversion in a remote tank system done at the tank?

  1. The wires near the tank have lower resistance than the long run to the display
  2. The clean 4-20 mA signal is converted before it runs along the noisy wire
  3. The monitoring location has no power for the A/D converter
  4. The tank has no ground connection for the transmitter
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Correct answer: The clean 4-20 mA signal is converted before it runs along the noisy wire

The noise is picked up along the long wire run.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 14.1: Introduction to Digital Communication

Practice signalling and communication

Questions last reviewed: 18 October 2026