The decibel (dB) is a logarithmic unit expressing the ratio between two power
levels: dB = 10·log₁₀(P₁/P₂).1 Radio relies on it because signal powers span an
enormous range and because gains and losses then simply add.
Decibels are logarithmic: every +10 dB is ten times the power, and gains and losses simply add.
How it works
Two anchors cover most mental arithmetic: +3 dB ≈ double the power, and +10 dB =
ten times. A chain of amplifier gains and cable losses becomes a running sum in dB.
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