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Noise vs interference and their limitations

Short answer

Noise is random, always present, and cannot be fully removed; interference is deterministic from other sources, often eliminable. Noise limits SNR, channel capacity, range, and receiver sensitivity. Interference causes crosstalk, reduces spectrum reuse, and demands better selectivity and filtering.

Differentiate between noise and interference. What are the limitations posed by them in communication system?

Noise vs interference

Noise is any random, unwanted electrical disturbance from natural or device sources. Interference is contamination by an unwanted signal from another man-made source, often of similar nature to the wanted signal.

PointNoiseInterference
NatureRandom, statisticalUsually deterministic, structured
SourceThermal agitation, shot effect, atmosphere, cosmicOther transmitters, machines, power lines, crosstalk
SpectrumBroad, often whiteAt specific frequencies of the interferer
PredictabilityCannot be predicted exactlyCan often be identified and located
RemovalCannot be removed fully; only reducedCan often be eliminated by filtering, shielding, planning
ExampleHiss in a receiver, snow on TVAdjacent channel station, ignition noise, hum

Limitations posed by noise

  1. Limits SNR and quality: analog output becomes noisy; digital links suffer bit errors.
  2. Limits channel capacity: by Shannon, C=Blog⁡2(1+S/N)C=B\log_2(1+S/N); lower SNR means lower maximum data rate.
  3. Limits range: the signal weakens with distance while noise stays, so repeaters are needed.
  4. Sets receiver sensitivity: the minimum detectable signal is fixed by the noise floor (kTBkTB and noise figure).
  5. Forces more power or bandwidth: higher transmitter power, low-noise amplifiers or wideband modulation (FM, spread spectrum) are needed.

Limitations posed by interference

  1. Crosstalk and unwanted programmes in the receiver, reducing intelligibility.
  2. Limits spectrum reuse: stations need guard bands and geographic separation, reducing the number of channels.
  3. Image and adjacent-channel problems require better selectivity, raising receiver cost.
  4. Jamming can block a link completely in strong interference.
  5. Requires shielding, filtering and regulation, adding design cost.

✓ Answer checked by Claude Opus 5.5 (high effort)

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