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Converts between power ratios and decibel scale for audio, RF, and other applications. Logarithmic scale matches human perception.
Formule
dBm = 10 × log10(P ÷ 0.001)
- P
- P value — Variable used in the calculation
Guide étape par étape
- 1dBm = 10 × log10(P ÷ 0.001)
- 2dBW = 10 × log10(P)
- 3Reverse: power (watts) = 10^(dBm ÷ 10) ÷ 1000
- 4Every 3 dB ≈ 2× power
- 5Every 10 dB ≈ 10× power
Exemples résolus
Entrée
Power 1W
Résultat
30 dBm
Erreurs courantes à éviter
- ✕Confusing dBm (power) with dBV (voltage) with dBu (relative to 0.775V)
- ✕Adding dBm values instead of multiplying power
Questions fréquentes
Why use decibels instead of watts?
Logarithmic scale compresses large ranges (1W to 1MW becomes 30 dBm to 60 dBm), easier comparison.
What's typical dBm for audio and RF?
Audio -20 to +4 dBu typical; WiFi transmit +17 to +30 dBm; cellular -30 to +33 dBm.
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