Sources of Noise in Analog Instrumentation Signals ~ Learning Instrumentation And Control Engineering Learning Instrumentation And Control Engineering

Sources of Noise in Analog Instrumentation Signals

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Noise
Many instrumentation systems involve the measurement of analog signals in which noise can be a prominent component. Analog instrumentation signals are commonly used for control purposes in most instrumentation facilities. These analog signals are very susceptible to various forms of noise which if not checked could corrupt the signals being transmitted for control purposes. The obvious result would be poorly controlled  and dangerous systems with very low signal integrity that could potentially be hazardous.
What is Noise?
Noise or interference can be defined as undesirable electrical signals that distort or interfere with an original (or desired) analog signal. Noise can arise from such sources as currents and voltages in power cables adjacent to the instrument signal cables, lightning and other electrical surges or transients, cross talk from other nearby cables and radio frequency interference. These forms of noise are referred to as external noise

There is also internal noise. They come mainly from thermal noise and imperfections in the electrical design. However the most problematic noise for instrumentation systems is external noise
Sources of Noise:
Common sources of noise in most analog instrumentation signals are:
  • Capacitive coupling
  • Inductive coupling
  • Ground Loops noise
  • Impedance Coupling (or Conductance Coupling)

Go to the next topic Ways to Reduce Capacitive Coupling in instrumentation signals