learn.howToCalculate
learn.whatIsHeading
Converts between power ratios and decibel scale for audio, RF, and other applications. Logarithmic scale matches human perception.
公式
dBm = 10 × log10(P ÷ 0.001)
- P
- P value — Variable used in the calculation
ステップバイステップガイド
- 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
解いた例
入力
Power 1W
結果
30 dBm
避けるべきよくある間違い
- ✕Confusing dBm (power) with dBV (voltage) with dBu (relative to 0.775V)
- ✕Adding dBm values instead of multiplying power
よくある質問
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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