Which unit of measure is used to measure wireless RF SNR?

Question

Options

• AdBi
• BdB
• CdBm
• DmW

• B
  90% (18)
• C
  5% (1)
• D
  5% (1)

Explanation

dB (decibels) is the correct unit for measuring Signal-to-Noise Ratio (SNR) because SNR expresses a ratio between two values (signal power vs. noise power), and dB is dimensionless - perfectly suited for representing relative comparisons rather than absolute measurements.

The distractors each represent different, specific measurements: dBi measures antenna gain relative to an isotropic radiator (a directional comparison, not a ratio of signal to noise); dBm measures absolute signal power relative to 1 milliwatt, which is used for individual signal strength readings, not ratios; and mW (milliwatts) is a raw unit of power used for absolute measurements, with no logarithmic scaling.

Memory Tip: Think of it this way - whenever you see a ratio or comparison between two RF values (like signal vs. noise), plain dB is your answer. Save dBm for absolute power levels and dBi for antenna gain. The "m" in dBm = milliwatt (absolute), while plain dB = relative.

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