Decibel watt

The decibel watt or dBW is a unit for the measurement of the strength of a signal expressed in decibels relative to one watt. It is used because of its capability to express both very large and very small values of power in a short range of number; e.g., 1 milliwatt = −30 dBW, 1 watt = 0 dBW, 10 watts = 10 dBW, 100 watts = 20 dBW, and 1,000,000 W = 60 dBW.

{\mbox{Power in dBW}}=10\log _{10}{\frac {\mbox{Power}}{1\mathrm {W} }}

and also

{\mbox{Power in W}}=10^{\frac {\mbox{Power in dBW}}{10}}

Compare dBW to dBm, which is referenced to one milliwatt (0.001 W).

A given dBW value expressed in dBm is always 30 more because 1 watt is 1,000 milliwatts, and a ratio of 1,000 (in power) is 30 dB; e.g., 10 dBm (10 mW) is equal to −20 dBW (0.01 W).

Although the decibel (dB) is permitted for use alongside SI units, the dBW is not.

See

Decibel suffixes (dB)
dBm (or dBmW) dBW dBV dBm/Hz PSD dBA dBZ (radar) dBsm dBc dBi dBFS dBrn dB-Hz
See also logarithmic unit link budget signal noise telecommunication

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